Timing Your Light, Food, & Exercise for Optimal Sleep, Energy & Mood | Dr. Samer Hattar

In this episode, I host Dr. Samer Hattar, Ph. D., Chief of the Section on Light and Circadian Rhythms at the National Institute of Mental Health. Dr. Hattar is a world-renowned expert on how viewing light at particular times adjusts our mood, ability to learn, stress and hormone levels, appetite, and mental health. We discuss how to determine and use your individual light sensitivity to determine the optimal sleep-wake cycle for you. We also discuss how to combine your light viewing and waking time with the timing of your food intake and exercise in order to maximize mental and physical functioning. Dr. Hattar is credited with co-discovering the neurons in the eye that set our circadian clocks and regulate mood and appetite. He explains why even a small shift in daylight savings leads to outsized effects on our biking because of the way that our cells and circadian clocks integrate across many days. And he offers precise tools to rapidly adjust to jet lag, shift work, and reset your clock after a late night of work or socializing. This episode is filled with cutting-edge data on the biological mechanisms of human physiology and practical tools for people of all ages. Read the full show notes for this episode at hubermanlab.com. Thank you to our sponsors AG1: https://athleticgreens.com/huberman LMNT: https://drinklmnt.com/hubermanlab Waking Up: https://wakingup.com/huberman Momentous: https://livemomentous.com/huberman Timestamps 00:00:00 Introducing Dr. Samer Hattar, Ph. D. 00:02:33 Sponsors: AG1, LMNT & Waking Up 00:06:15 Light, Circadian (24-hour) & Circannual (365-day) “Photoentrainment” 00:14:30 Neurons in Our Eyes That Set Our Body Clocks: Similar to Frog Skin 00:18:55 What Blind People See 00:20:15 When, How & How Long to View Light for Optimal Sleep & Wakefulness 00:30:20 Sunlight Simulators, Afternoon Light Viewing, Naps 00:33:48 Are You Jet Lagged at Home? Chronotypes & Why Early Risers Succeed 00:38:33 How to Decide Your Best Sleep-Wake Schedule; Minimal Light Test 00:42:16 Viewing Light in Middle of Day: Mood & “Light Hunger” 00:44:55 Evening Sunlight; Blueblocker Warning 00:48:57 Blue Light Is Not the Issue; Samer’s Cave; Complete Darkness 00:53:58 Screens at Night 00:56:03 Dangers of Bright Light Between 10 pm and 4 am: Mood & Learning 01:01:05 The Tripartite Model: Circadian, Sleep Drive, Feeding Schedules 01:05:05 Using Light to Enhance Your Mood; & The Hattar-Hernandez Nucleus 01:07:19 Why Do We Sleep? 01:08:17 Effects of Light on Appetite; Regular Light & Meal Times 01:18:08 Samer’s Experience with Adjusting Meal Timing 01:22:51 Using Light to Align Sleep, Mood, Feeding, Exercise & Cognition 01:30:15 Age-Related Changes in Timing of Mental & Physical Vigor 01:31:44 “Chrono-Attraction” in Relationships; Social-Rhythms 01:33:40 Re-setting Our Clock Schedule; Screen Devices Revisited 01:37:50 How Samer Got into the Study of Light 01:39:33 Clock Gene mRNAs & More Accurate Biomarkers 01:41:08 Light as Medicine 01:42:48 ADHD (Attention-Deficit Hyperactivity Disorder) 01:43:35 How to Beat Jet Lag: Light, Temperature, Eating 01:50:44 Vigor: The Consequence of Proper Timing 01:52:15 Waking in the Middle of the Night: When Your Nightly Sleep Becomes a Nap 01:54:10 Melatonin, Pineal Calcification 01:55:25 Our Seasonal Rhythms: Mood, Depression, Lethargy & Reproduction 01:59:08 Daylight Savings: Much Worse Than It Might Seem 02:05:27 Eye Color & Sensitivity to Light, Bipolar Disorder 02:09:28 Spicy Food, Genetic Variations in Sensory Sensitivity 02:10:52 Synthesizing This Information, Samer on Twitter, Instagram 02:13:00 Conclusions, Ways To Support the Huberman Lab Podcast & Research Disclaimer & Disclosures Learn more about your ad choices. Visit megaphone.fm/adchoices

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Andrew D. Huberman?

  Welcome to the Huberman Lab Podcast, where we discuss science and science-based tools for everyday life.

• 0:09Andrew D. Huberman?

  I'm Andrew Huberman, and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. Today, I have the pleasure of introducing Dr. Samir Hattar as my guest on the Huberman Lab Podcast. Dr. Hattar is the chief of the section on light and circadian rhythms at the National Institute of Mental Health in Bethesda, Maryland. Dr. Hattar has many important discoveries to his name. He was one of a handful of groups that discovered the light-sensing neurons in the eye that set the circadian clock. This is a fundamental discovery made in the early 2000s that has led to an enormous number of additional discoveries on how light regulates our sleep, our immune system,

• 0:52Andrew D. Huberman?

  our mood, mental health, metabolism, feeding, and many other important processes. If ever there was somebody who understands how all of these processes interact and can inform best practices for our daily behaviors, it's Dr. Hattar. During our discussion today, Dr. Hattar answers questions that are absolutely essential for us to know about our health and well-being. For instance, how to align our sleep schedule with our activity schedule, such as exercise, and how to align light, activity, and exercise with our feeding rhythms. He presents a new model of how light, activity, and feeding rhythms converge to support optimal

• 1:35Andrew D. Huberman?

  health, and when those are not aligned correctly, how our mental and physical health can suffer. It's a discussion that is rich with scientific mechanism, made clearly, of course, so everybody can understand, as well as specific protocols to deal with Shifts in day length, shifts in activity, and in order to optimize sleep, metabolism, and well-being of various kinds. I learned so much from Samer, as I always do. He is an absolute wealth of knowledge on all things related to light and circadian rhythms, physiology, and neuroscience. I don't think you'll find anyone else as knowledgeable about these topics as Samer, and so I'm delighted that he joined us here on the podcast to share this information. Before we begin, I'd like to emphasize that this podcast

• 2:19Andrew D. Huberman?

  is separate from my teaching and research roles at Stanford. It is, however, part of my desire and effort to bring zero cost to consumer information about science and science-related tools to the general public. In keeping with that theme, I'd like to thank the sponsors of today's podcast.

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• 4:29Andrew D. Huberman?

  And now, my conversation with Dr. Samer Hatarr. Samer, thanks for sitting down with me.

• 4:35Speaker 07

  My pleasure.

• 4:36Andrew D. Huberman?

  Yeah, we go way back. So you are best known in scientific circles for your work on how light impacts mood, learning, feeding, hunger, sleep, and these sorts of topics. So just to kick the ball out onto the field, so to speak, how does light impact the way we feel? So when I get up in the morning, I have the opportunity to interact with light in certain ways or to avoid light in certain ways. I have the opportunity to interact with sunlight or with artificial light. Maybe you could just wade us into what the relationship is between light and these things like mood and hunger, et cetera.

• 5:17Speaker 07

  Sure. So I mean, you do appreciate the effect of light for vision. So when you wake up in a beautiful area, beautiful ocean, light is essential. The sunrise, the sunset, blue sky, beautiful mountains. So that's your conscious perception of light. But light has a completely different aspect that is independent of conscious vision or image-forming functions. And that's how it regulates many important functions in your body. I think the best that is well-studied and well-known is your circadian clock. And the word circadian comes from the word circa, which is approximate and D N is day. So it's an approximate day. Why is it an approximate day?

• 6:01Speaker 07

  Because if I put you or any other human being who have a normal circadian clock in a constant conditions with no information about feeding time, about sleep time, about what time it is outside, you still have a daily rhythm, but it's not exactly 24 hours. So it will shift out of the solar day because it's not exactly 24 hours and hence the name circadian.

• 6:24Andrew D. Huberman?

  So just to ask a quick question about that. When you say you have this about 24 hour rhythm, how does that rhythm show up in the tissues of our body?

• 6:33Speaker 07

  Great. So, great question. So it shows up at every level that we know we studied. It shows up at the level of the cell, it shows up at the level of the tissue, and it shows up at your behavior. The most obvious for you is your sleep-wake cycle. You sleep and you're awake and sleep at the 24 hour rhythms. And if you measure the sleep-wake cycle of humans who are maintained in constant conditions, you will see that the period length of the sleep rhythm on average is more than 24 hours and in humans is 24.2 hours. So you'll be drifting 0.2 hours every day out of the solar day if you don't get the sunlight. So the sunlight adjusts that approximate day to an exact day. So now your behavior

• 7:17Speaker 07

  is adjusted to the light-dark environment or the solar day.

• 7:20Andrew D. Huberman?

  Okay, so if I understand correctly, if I were to go into a cave

• 7:24Speaker 07

  Yeah.

• 7:24Andrew D. Huberman?

  or I were to be in constant light

• 7:26Speaker 07

  Yeah.

• 7:27Andrew D. Huberman?

  and I didn't close my eyes

• 7:28Speaker 07

  Yeah.

• 7:29Andrew D. Huberman?

  in constant light, that I would still sleep in one coherent bout

• 7:34Speaker 07

  Yes.

• 7:34Andrew D. Huberman?

  and I would still be awake for more or less one coherent bout, maybe a nap. But the total duration of my day, so to speak, would be a little bit longer than 24 hours.

• 7:47Speaker 07

  Perfect.

• 7:47Andrew D. Huberman?

  But if I'm in a condition like most people are, where the sun goes up and the sun goes down, and I have some understanding of that sunrise and sunset.

• 7:56Speaker 07

  You don't have to have the understanding. You don't have to have conscious understanding. You have the detection.

• 8:00Andrew D. Huberman?

  Right.

• 8:01Speaker 07

  So circadian photoentraignment is the word we use in training the circadian clock to the photic environment. Is completely subconscious, you're not aware of it. It's not like vision where or image forming where you actually know what you're looking at. So it's all hypothalamic. It's part of the brain that is not consciously driven. So you actually do not know when it happens or when it doesn't happen. And that's what we'll get into when I tell you why light affects your mood and why sometimes people don't know how to deal with light to improve their mood, for example.

• 8:33Andrew D. Huberman?

  Okay, so this is a subconscious vision.

• 8:35Speaker 07

  Yes.

• 8:35Andrew D. Huberman?

  Okay. Before you tell us about how light impacts mood, I'm curious. What is the relevance of adjusting this clock from a little bit longer than 24 hours to 24 hours? I mean, it seems like a small difference, 24 hours and 40 minutes or 24 hours. Like what's the relevance? I mean, why should we care about that short difference?

• 8:57Speaker 07

  So let's do the math. If you shift out point two hours a day, in five days, you're shifting out one hour. So you're literally one hour off in your social behavior in five days. In 10 days, you're two hours off. And if you're an organism that is living in the wild, shifting out of the right phase of the cycle, you could either miss food or you could become food. So it's really essential for survival. I think it's one of the strongest aspects of survival for animals to have the anticipation and the adjustment to the solar cycle.

• 9:29Andrew D. Huberman?

  And for humans as well, when you say animals, I'm assuming that applies to us.

• 9:33Speaker 07

  Yeah.

• 9:34Andrew D. Huberman?

  I see. So even though it's just a short bit longer than 24, if you, if that accumulates over days, then you could find yourself very much out of phase with the rest of your, your species essentially.

• 9:46Speaker 07

  So let's say it's point two hours. So in five days, it's one hour. In 25 days, it could be five or six hours. You could be in New York and you're feeling as if you traveled from New York to London. So you will be having jet lag in New York, even though you didn't do a jet lag travel. So it's very important for the adjustment. And if we have time, maybe we could talk about why this is important for seasonality, because also it allows animals to anticipate the change in season. And the more you're high in, in the north or the south, the more that these weather changes occur very harshly and you have to be ready for them. And that happens in, in us as well.

• 10:28Andrew D. Huberman?

  All right, well, we will definitely get into seasonality. Okay, so we've got this subconscious vision that aligns us with the turn of the earth. How does that work? What's the, what is the, the machinery that allows that to happen? And how does that machinery work?

• 10:46Speaker 07

  Yeah, so we know, we knew that in mammals, including us, we are mammals, humans, that the eyes are required for this function. So if humans are born without eyes or the optic nerves are damaged, humans are not able to adjust to the solar cycle. So we know that the eyes are required. And since we thought we knew about the eyes a lot before 2000, we thought that-

• 11:09Andrew D. Huberman?

  What, you say before the year 2000?

• 11:10Speaker 07

  Before the year 2000, yes. We thought it's these photoreceptors in your retina that allow you to see. So in, in the human retinas, there are two types of photoreceptors. They are called rods and cones because of their shapes. And these rods and cones simply take the photon energy, which light is made of, and they change it in a way to an electrical signal that allow us to build the image of the environment in our cortices.

• 11:36Andrew D. Huberman?

  Subconsciously.

• 11:37Speaker 07

  Consciously, in this situation, because it's vision, right? It's image-forming vision. It's a, it's a visual cortex and association, associative cortices, which allow you to build conscious perception of the environment. However, people have found, including me, with the work of David Burson and Ignacio Proventio, that there is a subset of ganglion cells. The ganglion cells are the cells that leave the retina, their axon, leave the retina, and project to the brain. So these were stood to only relay rod and cone information from the light environment to the brain. We found that a small subset of these ganglion cells are themselves photoreceptors that were completely missed in the retina.

• 12:19Speaker 07

  And these are the photoreceptors that relay light environment, subconsciously, to the areas in the brain that have and house the circadian clock or the circadian pacemaker, which adjusts all the clocks in our bodies to the central brain clock, that allows them to entrain to the 24-hour light dark cycle.

• 12:40Andrew D. Huberman?

  Incredible. So, as I recall, because I was a graduate student at the time, in the year 2000, there was this landmark discovery made by you, Iggy Provencio, David Burson, and others, that these cells exist that can communicate day and night information to the brain.

• 12:55Speaker 07

  Yeah.

• 12:55Andrew D. Huberman?

  In this very small subset of cells. Since then, I've heard, but maybe you can confirm or refute, that this system that connects the eyes to the rest of the brain is actually the most ancient form of vision, that this is probably the form of vision that some early version of human beings had before they had pattern vision, before they could see colors and shapes and motion and all that. And that the same cells that perform this role are actually similar to insect eyes. I think I heard David Burson say once that we actually have a little bit of the fly eye in our eye. What's he talking about?

• 13:33Speaker 07

  Yeah, so it's really interesting, actually, because these same ipRGCs we discovered, they contribute a little bit to image formation, and now work from Tiffany Schmidt specifically have proven that they do contribute to image-forming functions. But they contribute to very limited aspect of image formation. So it fits your hypothesis that these are an ancient photoreceptors. The other thing that adds to that hypothesis is that they are expressed in cells that don't have any modification that make them look like photoreceptors. So the photoreceptors that I told you about that are important for vision, image formation, they have very specialized structures that allow them to pack these structures with photopigments.

• 14:18Speaker 07

  These are the photodetecting proteins, so they could detect a high sensitivity of photons that pass through them. These ipRGCs, these new photoreceptors, don't have these specialized structures. So they just really need a lot of light. At the time, we thought they need a lot of light to be activated. So that's why we think they are ancient and that's why I think they adjust to ancient functions that are as important as regulating your body circadian clock to the solar environment, to solar day or to the light dark cycle.

• 14:55Andrew D. Huberman?

  So you you mentioned ipRGCs, intrinsically photosensitive. So these are cells that connect the eye to the brain that behave like photoreceptors, essentially. And then you mentioned melanopsin, which is the actual pigment that converts the light into the electrical signal, more or less. And my understanding is that melanopsin was identified first in frog melanophores.

• 15:16Speaker 07

  Yes.

• 15:17Andrew D. Huberman?

  So does that mean that we have like little pieces of frog skin in our eyes?

• 15:21Speaker 07

  So honestly, David Burson say you have a fly in your eye because it sounds better. The more accurate, I think, is that you have a frog skin in your eye. It's not as catchy. But really, melanopsin, really, the name melanopsin is from melanocyte opsin. So it's melanopsin because it was found in the frog melanocytes. You know, the frogs can change their color depending on light. And melanopsin drives this response. So when Ignacio Proventio first discovered these opsin's in frogs, luckily, he was smart enough to see if they are expressed in the frog eye. They were expressed in the frog eye and it's what appears to be retinal ganglion cells, which I told you, the one that connect the eye to the brain. He had the insight to go and see if they are expressed in the monkey eye.

• 16:05Speaker 07

  And he found that they are also expressed in what appears to be retinal ganglion cells. And really, that what opened the field wide open. Then David Burson did the seminal experiment where he went to the brain where the central oscillator, the oscillator that drives circadian rhythm in the brain called the suprachaosmatic nucleus that has been known for many years to receive retinal input. And he labeled the cells that project there. And then he found that even if you destroy rods and cones, you could get light responses from these cells. So you could imagine, he he nearly fainted when he saw that these cells can respond independent, completely in the absence of rod and cone input.

• 16:45Andrew D. Huberman?

  I'll never forget reading those papers in 2000, 2001. I was at the meeting in DC when Iggy, Ignacio Iggy, we call him Iggy, showed this image of this, basically what is frog melanophores in the human eye. And everyone was like, oh, my goodness, this is the thing. And I want to get into how light actually can control circadian rhythms in a moment. But I think it's worth mentioning now that people who are pattern vision blind, so people who cannot see and no conscious vision, but have eyes, many of them still have these cells, these melanopsin intrinsically photosensitive cells, and can essentially match or entrain, as we say, onto the light-dark cycle.

• 17:29Speaker 07

  In fact, they possibly have no problems in circadian phototrainment. They'll have enormous sleep-wake cycle.

• 17:34Andrew D. Huberman?

  But they're totally blind.

• 17:35Speaker 07

  But they are totally image blind. And what's really interesting is that, and this story I heard from Chuck Seisler, so I'll give him credit, that some of these people who are image blind, usually they get dry eyes and they give them a lot of pain. And doctors used to think, oh, since they are image blind and they're getting dry eye, why don't you just remove their eyes? They're not using them anymore. And the minute they would remove their eyes, they start having cyclical sleep problems, indicating that now they are not entraining to the light-dark cycle and are having cyclical jet lag when their clock shifts through the light-dark cycle.

• 18:11Andrew D. Huberman?

  That's really interesting. And I hear from a number of blind people, you know, in my various aspects of my job, and a lot of them have issues with with sleep. I think in part because they don't realize that they too need to see light at particular times of day or night in order to match their schedule.

• 18:28Speaker 07

  Absolutely.

• 18:28Andrew D. Huberman?

  Well, I think that's a perfect segue for us to talk about how light and viewing light can impact our sleep-wake rhythms. And then we will move into some of the other ways in which light can impact other forms of bodily function.

• 18:43Speaker 07

  Yeah, so I love the way you set it up because one of the most interesting and difficult aspects of.

• 18:51Speaker 07

  Trying to educate people about light effect on subconscious vision is that is subconscious. So we're all aware of what we think is intensity because we see the room. But you know, if you talk to people who know how to take photographs and stuff like that, they know that the intensities varies greatly. But our system, because we have to see the same way in very bright conditions and very dim conditions, we're not very good at estimating intensity consciously. So when you try to tell people about intensity, you really struggle because they think they know intensities, but they really don't.

• 19:25Andrew D. Huberman?

  You mean light intensity?

• 19:26Speaker 07

  Light intensity. So so that the cones themselves have an incredible ability to adapt to different light conditions. So you can see at all different conditions, otherwise it'd be a disaster. You know, if you don't change the the setting on your camera and you go from inside the room to the outside, it becomes completely white, you don't see anything. So if your cones don't adapt to the environment, then you're not going to be able to see in this room and in on the beach, right? But the problem is your your IPRGC is the cells that we talked about. They measure intensity pretty well. They really know what intensity is. They have a very good linear measurement of intensity. They don't adapt as well, they don't adapt actually that much, to be honest.

• 20:11Speaker 07

  So that tells you that subconsciously the system is used to measuring light intensity in a natural environment. Because when you're now in a natural environment, you don't have, you know, industrialized lighting, then you, you know, your system is functioning very well. But now, when we change these environments, we could really mess up ourselves. So you have to teach people how to understand intensity. And that's something that you have to explain to people. And I think I love to do it myself. I do it in what is called the lowest amount of light required to allow you to see comfortably. So you have to do this as a fun experiment.

• 20:49Andrew D. Huberman?

  Okay, so explain to me how this goes. And maybe we could break it up in the day into um three or four parts. So let's say, assuming that most people wake up in the morning, as opposed to night shift workers, etc., we could talk about later. But they wake up in the morning. So let's divide the day into quarters. What is what is the proper way to interact with light in the first part of the day?

• 21:12Speaker 07

  So I honestly think the easiest thing is waking up. Get as much light as you can.

• 21:18Andrew D. Huberman?

  To your eyes.

• 21:19Speaker 07

  Yeah, it's really nice. Your system is primed. If you're entrained, it's primed to get light. The sun should be out. Most animals in the wild, they actually seem to track the sun. The sun has a huge influence on life on earth. It's actually, life on earth is because of sun. So that's easy. In the morning, when you wake up, you need light.

• 21:39Andrew D. Huberman?

  Okay, so what is the behavioral practice that you recommend? Does it, let's say, somebody is in a condition where there's a lot of cloud cover.

• 21:46Speaker 07

  Yeah.

• 21:47Andrew D. Huberman?

  Is it important to get outside?

• 21:48Speaker 07

  So I have to tell you, the cloudiest day is gonna be much more brighter than your room. You could ask any photographer. A cloudy day, unless it's really dark, dark clouds. Usually cloudy days have much more bright outside than inside the room, even when you have good lighting inside the room. So I think in the outside is usually, even when it's cloudy, you're gonna get enough intensity to help you adjust your cycle to the day-night cycle.

• 22:14Andrew D. Huberman?

  So how long do you, these are general rules of thumb, but how long do you recommend people go outside?

• 22:20Speaker 07

  If you do it daily, you possibly need very, if you do it daily, because remember, this thing is gonna happen on a daily matter.

• 22:26Andrew D. Huberman?

  So the clock is tracking it on a regular basis?

• 22:29Speaker 07

  Absolutely. It's photon counting, it's tracking. I would say fifteen minutes. If you don't do it daily, you may wanna increase it. And we'll talk about when you travel, what you could do. But yeah, fifteen minutes should be fun. You do it more, it doesn't hurt.

• 22:42Andrew D. Huberman?

  And through a window, I was, my understanding is that through a window, it dramatically decreases the amount of light energy coming in.

• 22:48Speaker 07

  It depends of how, you know, how thick the windows are and how dark they are. So it's, but it's also nice to go outside and to feel the season.

• 22:57Andrew D. Huberman?

  Sunglasses off?

• 22:59Speaker 07

  I don't use sunglasses.

• 23:00Andrew D. Huberman?

  Yeah, but you have the, your Jordanian photopigment, you know, so, yeah. Whereas my eyes are very sensitive, right?

• 23:07Speaker 07

  No, so I, but I personally, you know, if I'm in the shade or if it's not incredibly bright, I try to, especially in the morning. But I'm also an early person, so we have to differentiate between early.

• 23:18Andrew D. Huberman?

  What time do you wake up?

• 23:19Speaker 07

  I wake up at four thirty in the morning.

• 23:20Andrew D. Huberman?

  But the sun isn't.

• 23:21Speaker 07

  It's not out yet, so.

• 23:23Andrew D. Huberman?

  So what do you do? You turn on artificial lights?

• 23:25Speaker 07

  I usually don't turn on artificial light because I know the sun is gonna come up eventually. But that's why I don't like the change. In the timing that they do.

• 23:33Andrew D. Huberman?

  Wait, well, what do you do between four thirty AM and seven AM?

• 23:36Speaker 07

  I mean, I look at my computer.

• 23:38Andrew D. Huberman?

  Oh, I see.

• 23:39Speaker 07

  So possibly I get enough light, but but in reality, I mean, as long as you let your body get the morning sunlight, which I think is really to me, and I there is no evidence, but to me, this is, if you look at all animals, plants, this morning sunlight seems to be very important. And I I, you know, we don't have experiments to show it, but I have a gut feeling that it has a huge impact on humans.

• 24:04Andrew D. Huberman?

  Well, Jamie Zeitzer's lab at the Stanford Sleep Lab has shown that these early morning light flashes can adjust the total amount of sleep that one will get, makes it easier to get into sleep.

• 24:15Speaker 07

  Absolutely.

• 24:15Andrew D. Huberman?

  Okay, so.

• 24:16Speaker 07

  And and and Ken Wright also did this beautiful camping experiments that.

• 24:22Andrew D. Huberman?

  Right, maybe you should describe those, because those are beautiful experiments.

• 24:24Speaker 07

  They are beautiful experiments. He he he took these, you know, college students that had a late onset of sleep and late waking time. And then he said, let's go camping and just don't use any artificial light. And you could go to sleep as as as late or as early as you want and wake up as late as early. And he found a huge shift in their sleep pattern just by exposing them to the light dark cycle. I mean, so.

• 24:49Andrew D. Huberman?

  And it lasted.

• 24:50Speaker 07

  And it lasted.

• 24:51Andrew D. Huberman?

  Even after they came back.

• 24:52Speaker 07

  Exactly.

• 24:52Andrew D. Huberman?

  Two days of camping, reset the circadian clock.

• 24:55Speaker 07

  Seven days, but it it lasted. Yeah, it's pretty amazing. Yeah, it's really incredible.

• 24:59Andrew D. Huberman?

  Okay, so get bright light of some sort early in the day, ideally sunlight. Even on a cloudy day, it's going to be brighter than indoor light.

• 25:08Speaker 07

  So that's easy.

• 25:09Andrew D. Huberman?

  Okay, so then.

• 25:10Speaker 07

  And and the other thing that I would like to mention to people, if you think it's very dim outside, let's say it's very cloudy, stay longer. So remember, intensity is only one component. Duration is also important, because remember that the circadian system is not like the image system. In the image system, you have to change every second because you're looking at different objects. You have to change your perception, but for the circadian system, it's trying to figure out where am I in the day night cycle? So the more you give them the information, the better you are. So if it's very bright, you don't need a lot, because it's clearly gonna make you fire like crazy. But if it's not bright, stay longer, stay for one hour. You know, have your coffee outside or something like that. It's just gonna help.

• 25:54Andrew D. Huberman?

  I think you said something extremely important, which is that this circadian system is trying to figure out when you are in time.

• 26:01Speaker 07

  Exactly.

• 26:01Andrew D. Huberman?

  Not where you are in space.

• 26:03Speaker 07

  I said where you are in time, I meant when you are.

• 26:05Andrew D. Huberman?

  Oh, no, no, I wasn't correcting you. I just meant that it, I think fundamentally, that's the, the, the incredible thing about this system. That you have this clock, this 24 hour clock in your brain, but it, it needs to be synchronized to the outside. So could we go a little deeper into this circadian setting behavior and come up with some general rules of thumb? So let's say it's a very bright day, extremely bright. You know, no clouds, sun's out.

• 26:34Andrew D. Huberman?

  You said 10 minutes, 15 minutes.

• 26:35Speaker 07

  And I'll tell you, if you're sensitive, don't, you don't even have to go in the sun. You could be in the shade. There's gonna be so many photons out there in the shade. It's gonna be perfect. You don't even have to see the sun. You don't have to have the sun. You know, it's great for vitamin D. That's a different story. You could do this for your skin and, and, you know, protect your skin. That's not my area of expertise, but for, for that effect on the circadian system. As long as you're outside in the shade and it's sunny day, 10 to 15 minutes should be ample amount.

• 27:06Andrew D. Huberman?

  Okay, and then let's, let's say it's kind of overcast. Um, you know, it's not particularly bright or there's, you know, solid cloud cover, but you know, the, obviously the, the sun is out, but uh, you're, it's not as bright. How long do you think it would take to set the clock?

• 27:20Speaker 07

  10 to 15 should be sufficient. Stay for a half an hour, stay for 45 minutes. If it's very dark cloud, yeah, stay for longer.

• 27:27Andrew D. Huberman?

  Okay, and if, um, for some reason, one finds themselves very far north and it's very, very dense uh, cloud cover, how long and at what point should somebody consider using an artificial light source to mimic the sunlight?

• 27:43Speaker 07

  Yeah, honestly, this is where we don't have a lot of information still. Because this is where we're gonna discuss this maybe in more detail, that if you put humans in artificial conditions, the circadian system is very sensitive to light.

• 27:58Speaker 07

  But in reality, in the real environment, light also is affecting other aspects that are independent of the setting of the circadian base maker.

• 28:08Andrew D. Huberman?

  Okay.

• 28:08Speaker 07

  And these which we call the direct effect of light on mood, for example. So that is very hard to figure out what intensity you need to use. And we haven't done enough experiments because the system has been discovered just recently. But I would say if you use bright light in the morning, and I mean, it's hard for me to give numbers. It can get complicated.

• 28:31Speaker 07

  But yeah, I mean, if you're, honestly, if you're that far north and you're in the winter and you wanna get, make sure you don't, use these light boxes. I, I would suggest that personally, but that's it.

• 28:41Andrew D. Huberman?

  I use, um, it's actually not designed for circadian setting, but I have a, a nine hundred and thirty lux light pad that I bought. And I bought it, um, it's, they're very affordable compared to the, uh, dawn simulating lights, which are, which are quite expensive, frankly. And I, I put it there and so I just basically, when I wake up in the morning, I use that until the sun comes out. And then I make sure, once the sun is out, I go outside. But I keep that thing on all day. And I don't know if that's good or bad, is it good or bad?

• 29:09Speaker 07

  I honestly, I don't think being exposed to bright light in the day is gonna ever be bad. Because really, if you're outside in the day, unless, you know, the worst gonna happen is the temperature is very high. Your body's gonna say, don't dehydrate and go to sleep. So you, you could tell actually sometimes when it's very hot, the more you get exposed to bright light, the sleepier you feel in the afternoon, which is counterintuitive. So.

• 29:33Andrew D. Huberman?

  And that's to protect us, you think, against dehydration?

• 29:36Speaker 07

  I think if you think about the human evolution from near the equator, in the, uh, between noon and a certain time in the afternoon, it would have been very hard for you to maintain physiological homeostatic function, being active at this very high temperature time. So I think napping was a way, that's why I think it has a major function, which is still, napping was a way to somehow take you away from that dangerous zone. And maybe that's why people in the north, they say in the winter, we can't wake up in the morning because they don't have this long light, so they sleep it more at night. But in the summer, they say, we feel like we can't go to sleep. We have to put all these dark curtains. So I think, you know, venturing that up, that much nor, up north,

• 30:21Speaker 07

  has been, came up with problem because evolution was used to a certain light environment. That was completely. Changed with a human, with other animals, I think that lived there longer. They have come up with very interesting adaptation of actually measuring even very small changes in the light, in the light intensities that still occur. So even if you're near the, the, the poles, even though it's always light, but there is a change in the light intensity across the day and night cycle. So your system, if it's linear, and remember, I told you that IP RGCs are incredibly linear, can still measure, oh, this is lower light than higher light, if, if, if the organism has the ability to do that.

• 31:02Andrew D. Huberman?

  I see. Yeah, it's, it's interesting. I've, I've spent so much time learning from you, fortunately, about these cells. And yet I never really appreciated until now how, on the one hand, they are tracking the amount of light to understand when we are in time relative to the 24 hour cycle. But also that you keep mentioning this, this linear measurement of intensity, that they really are trying to figure out when we are in time by measuring the intensity of light. And of course, the sun is the most intense source of light available to us. So, okay, so I think we've nailed down that first part of the day.

• 31:38Speaker 07

  Exactly.

• 31:39Andrew D. Huberman?

  Basically, it's get 10 to 30 minutes, depending on how bright it is, and try and do that as, as often as possible to give the system a regular.

• 31:45Speaker 07

  Daily is the best. This system is really about, and, and you'll see that even for the effect on depression. It's about multiple days. It's, it's, so you don't have to worry if you missed it one day. You know, stay longer if you want, but if you're in a hurry and you want to do other stuff, that's a great recommendation.

• 32:03Andrew D. Huberman?

  So you might want to compensate with some extra time if you missed a day or two. And this is why I, I've heard you say before, it's entirely possible to get severely jet lagged without traveling.

• 32:12Speaker 07

  Absolutely.

• 32:13Andrew D. Huberman?

  Simply by staying in, being on your phone too much, not getting the sunlight.

• 32:17Speaker 07

  And you saw this during the pandemic. A lot of people mentioned that their sleep-wake cycles suffered a lot. Because if you're not going out and if you're staying at home and you don't have big windows and you're waking late, waking up late, and then you're using very bright light till late at night, your body's gonna shift. And now your day is gonna start instead of like really when the sun comes up, let's say at six o'clock in the morning, it's gonna, your day is gonna start at 11 o'clock in the morning. That's what your body's gonna think is the beginning of the day. So then you're not going to be able to sleep at 10 o'clock at night because now that's really for for your body is completely different timing. And you could see this happen during the pandemic at a very high scale.

• 33:02Speaker 07

  People get delayed in their sleep wake cycle a lot.

• 33:05Andrew D. Huberman?

  And there is this idea of chronotypes that we all each intrinsically have a best rhythm of either being a morning person, you call yourself an early person, or a night owl, or more of a kind of standard, you know, to bed around 10:30 up around seven type thing. And the and I think there are now good data, correct me if I'm wrong, from the National Institutes of Mental Health and elsewhere, showing that the more we deviate from that intrinsic rhythm, the more mental health issues and physical health issues start to crop up.

• 33:36Speaker 07

  So there is great data on this, and there is a couple of things that complicate this. The first is the people who usually are late, they tell you that the society doesn't accommodate.

• 33:46Andrew D. Huberman?

  What by late, what do you mean? People that wake up late and go to sleep?

• 33:49Speaker 07

  Go to sleep late and wake up late. They they have an overwhelmingly higher level of depression and failures. I mean, clearly, I mean, the reason the people say sleep early, wake up early or better because human notice that people who wake up, go to sleep early and wake up early, they do better in life, they notice that.

• 34:09Andrew D. Huberman?

  They just perform better.

• 34:10Speaker 07

  They perform, but the question is, is that intrinsic to the system or is that society? Because society start things usually early or late, that's a hard question.

• 34:19Andrew D. Huberman?

  We discriminate against late risers.

• 34:20Speaker 07

  In a way, we discriminate, right? But the other explanation is can RIS experiment, these late riser, if they were truly chronotypically late, why would they shift so easily when you put them in the? If you were really chronotypically late and there is a phase relation between the light dark environment and your circadian clock, then doing this camping experiment should not have cause much changes because it's not. That you know, you, you, light is gonna affect you in a certain way is that this is the relationship that your body decided that I'm a late sleeper, late waking. So I, I'm honestly, I'm still, I'm, I'm unable to figure out how much of this late waking up

• 35:03Speaker 07

  is controlled by the light environment and how much is intrinsic. I'm sure there are differences, but are they as big as we see in the environment? Because you have people that go up to sleep at seven P M. and wake up at one A M. These are clearly advanced phase.

• 35:19Andrew D. Huberman?

  So people that go to sleep at seven P M. and wake up at one A M.

• 35:22Speaker 07

  Yeah.

• 35:22Andrew D. Huberman?

  And feel good doing that.

• 35:24Speaker 07

  I'm not so sure they feel good, but a lot of the time you talk to people, they say they are high achievers, but they suffer because you know, they, they wake, they go to seven P M. wake up advanced phase sleep syndrome, they call it, they, they call it a syndrome. But you know, but then you have people who would not be able to sleep till five A M. And, and not be able to wake up till three P M. Right? And I'm not so sure that the circadian system is that variable in the human population. I mean, clearly there are maybe some genetic factors that make a small percentage of like everything with a bell shape. But I think most of the time, the light environment may play a role. And once, as you, as we've talked about, this is a long term effect of light.

• 36:06Speaker 07

  Once you get into a rhythm, and I, I don't mean it as a pun, in reality, once you get into a rhythm, it's hard to break out of that rhythm. Because if you start sleeping late and waking up late, you're not getting the morning sunlight.

• 36:19Andrew D. Huberman?

  Right.

• 36:20Speaker 07

  And so you, you're just gonna be late. And if you're like me, waking up early, you're getting the morning sunlight, you're getting what Zeitzler said, uh, uh, I said his last name wrong, um, the one in Stanford who did the, the.

• 36:34Andrew D. Huberman?

  Oh, uh, Jamie Zeitzler.

• 36:35Speaker 07

  Zeitzler.

• 36:35Andrew D. Huberman?

  Yeah.

• 36:35Speaker 07

  Yeah.

• 36:36Andrew D. Huberman?

  He actually worked for Zeitzler, so Zeitzer and Zeitzler. Yeah, there are a lot of Z's, Z's and I's in those, in those, in their names.

• 36:43Speaker 07

  Yeah.

• 36:43Andrew D. Huberman?

  Both phenomenal scientists.

• 36:44Speaker 07

  Yeah.

• 36:45Andrew D. Huberman?

  Well, what, what it seems to me is the case is that the only way to really know if you're meant to be an early bird, as they call it, an early person or a late person or somewhere in between, is to get morning sunlight and figure out whether or not that makes you feel better.

• 37:01Speaker 07

  And to understand.

• 37:04Speaker 07

  To be educated about how to measure intensity, how to measure, I put it between quotation, because you either get a measuring device, but you cannot depend on your eye to measure intensity.

• 37:16Andrew D. Huberman?

  Okay, so how do we do that? Because you keep coming back to this. So that tells me that's important.

• 37:21Speaker 07

  It's very important.

• 37:22Andrew D. Huberman?

  So there are apps, like free apps, like Light Meter, where you can walk around and hold the button down and see how many lux, you know, are in the environment.

• 37:30Speaker 07

  These are complicated because you have to point them to specific regions.

• 37:34Andrew D. Huberman?

  So how do people start to develop an intuitive sense of the measurement of intensity?

• 37:40Speaker 07

  Yeah, I think at one point, I posted on Instagram how I keep my nighttime at home. And I found out that my night vision is very strong. So I found out that especially in the winter, I only need candlelight. So I literally use these tea lights. And I put like fifteen or twenty of them.

• 37:58Andrew D. Huberman?

  How romantic.

• 37:59Speaker 07

  And it's so nice. I could see it clearly doesn't affect my circadian system.

• 38:04Andrew D. Huberman?

  You and your cats.

• 38:05Speaker 07

  And my wife.

• 38:06Andrew D. Huberman?

  And your wife, of course.

• 38:07Speaker 07

  It's just great, right? But I don't expect people to have the same night vision as me. So the simple, I mean, I tell people, do the experiment. So if you put three or four lights in your room, switch two, sit for fifteen minutes.

• 38:22Andrew D. Huberman?

  Switch two off.

• 38:23Speaker 07

  Switch two off. Let's say you're using five. And see, after fifteen minutes, you will not recognize you switch these two off. My gut feeling is that most people would need at least ten times less light than they use at night to see. The problem, people use it because most of the time they didn't see the morning sunlight. They are actually hungry for light without their knowledge. So they come switch all these lights on, but at the wrong time because they woke up late.

• 38:49Andrew D. Huberman?

  Okay, now I understand. So this morning light viewing goes way beyond

• 38:54Speaker 07

  Absolutely.

• 38:54Andrew D. Huberman?

  setting your clock. It's also a way to determine how little light you need later in the day.

• 39:00Speaker 07

  Exactly.

• 39:01Andrew D. Huberman?

  And we're going to talk about this in a moment, but How little light you get later in the day is a very strong determinant of things like when you will wake up, whether or not you wake up feeling refreshed, etc. Let's, let's move.

• 39:12Speaker 07

  And that's why.

• 39:13Andrew D. Huberman?

  Yeah.

• 39:13Speaker 07

  I'm gonna break it on your show, Andrew, that I'm gonna tell you, I think there is something else that people need to think about, which is the tripartite model. That this model incorporate three components, which we'll talk about in details, that allows us, humans and all animals, to incorporate the circadian clock and its relation to light, the homeostatic drive, and the direct effect of the environment, which includes stress, light, all kinds of stuff. They have to be incorporated together. If you think, that's what I think right now, if you think of one alone, you will always miss something. And when you think of them as a whole, things really become clear. It's actually quite amazing.

• 39:56Andrew D. Huberman?

  Okay, well, we will definitely want to hear about your tripartite theory and go into detail about this homeostatic mechanisms. I want to make sure that for people who are thinking now, I'm sure, about light and how it impacts them. So, the morning light viewing behavior, I like to think we've tacked down clearly. And thank you for that, because there's so much information out there. I've tried to relay that information. Of course, you're my primary source for all things circadian, as well as Jamie and others, of course, and Matt Walker. But I think you've made that very, very clear. Now, let's say I've gotten my morning sunlight, okay? Maybe my bright artificial light. And throughout the day, you said to get a lot of light. So I'm working at my desk, maybe I'll, I'll go out during the day a few times, but I'm

• 40:41Andrew D. Huberman?

  working at my computer, I'm doing things. Is there anything about light viewing in the middle of the day that people should keep in mind? Or can they just sort of freestyle it, depending on what they're doing? Most people are not, you know, in a dark room throughout the day.

• 40:55Speaker 07

  My gut feeling, if you got your morning sunlight, you walk from your car slowly, or you walk to work, you didn't wear sunglasses when the lights were still dim in the morning, that you could freestyle it. That even if you don't get a lot of light, there is a way. To just, you know, in the day, you don't have to just worry about getting a lot of bright light, but personally, I like to do that. So I go out at lunch and, and have my lunch outside as well. This reminds the body that here it is even brighter now. But the evidence is that you could literally help your circadian clock by giving lights at dawn and dusk. But again, if you think of the tripartite model, this may be important for a circadian clock,

• 41:38Speaker 07

  but is it important for your mood? So that's where I think you need, or the homeostatic drive. So that's where you need to think about it. So for the clock, for entraining your clock, you literally can entrain it only by the dawn sunlight. You actually don't need dawn and dusk.

• 41:54Andrew D. Huberman?

  Okay.

• 41:55Speaker 07

  People even forget that.

• 41:56Andrew D. Huberman?

  Yeah. And I appreciate that you're distinguishing between circadian effects and other effects of light.

• 42:01Speaker 07

  Yes.

• 42:02Andrew D. Huberman?

  You're being very precise, which is appreciated. Until we hear about this tripartite model, which we will cover, for the, for the sake of the discussion, let's treat the light viewing behavior as what are the benefits or drawbacks of viewing light for all biological purposes, not just circadian settings. So in the morning, it's clearly gonna set the clock. And then during the day, if I understand correctly, the idea is to get as much bright light as you can, because you're feeding, it sounds like a sort of light hunger.

• 42:32Speaker 07

  Exactly.

• 42:33Andrew D. Huberman?

  I see.

• 42:34Speaker 07

  I love this way to put it. I think there is a weird light hunger, considering that we're not photosynthetic organisms. There is a weird light hunger in animals that they need to measure, they need, they, they need measure. And I think that relates to the season, because the whole reproduction cycle of animals is gonna depend on the availability of food in the environment. And if you don't know when the season's gonna happen, they don't have calendars, it's gonna be very hard to survive. So I think that's why we have this light hunger. That's a major hypothesis. It's not being tested.

• 43:06Andrew D. Huberman?

  Interesting. So then afternoon and evening start to approach. So I've had this weird experience, maybe you can psychologically or biologically diagnose me now, Samer. So where if I go into a movie in the afternoon, like a matinee,

• 43:21Speaker 07

  Uh huh.

• 43:22Andrew D. Huberman?

  And I come out and it's dark, I notice a significant drop in my mood and my ability to go to sleep. Whereas if I get some view of the light in the evening, doesn't have to be the sunset, although sunsets are nice, but I get some light pulse in the afternoon that I have no trouble whatsoever.

• 43:42Speaker 07

  And it happens in a daily, on a, on a single time to, to watch them?

• 43:46Andrew D. Huberman?

  More or less.

• 43:47Speaker 07

  That's interesting.

• 43:48Andrew D. Huberman?

  And then you mentioned the camping experiment, where when they went camping, they're seeing the sunrise and the sunset. So what should people do in the afternoon slash evening time in terms of their light viewing behavior?

• 44:01Speaker 07

  I mean, the best thing to do is to let the natural light creep in into darkness, right? That would be the best. But clearly, that would be inefficient. You, you wanna go home, you wanna read, you wanna talk to your kids, you wanna talk to your family. So I think, you know, it's nice to extend the day. I don't think that's wrong. If you somehow can block that light from affecting your circadian clock.

• 44:25Andrew D. Huberman?

  So should people use blue blockers in the evening?

• 44:28Speaker 07

  I personally do not like any blockers that take a single wavelength of light. Because again, if you think of a holistic, holistic approach, yes, the blue blocker is gonna prevent you from affecting your circadian clock very much, but then your vision is gonna be distorted because we always see in full spectrum. The sun has this beautiful spectrum, right? And then when you start seeing without the blue, things look yellow and it can get really weird, right? I mean, so I, I personally, I've tried the blue blocker and I couldn't even wear them. I, I thought they were just really horrendous, to be honest.

• 45:06Andrew D. Huberman?

  Well, along the lines of blue blockers, I think a lot of people mistakenly wear them all day long.

• 45:11Speaker 07

  Oh, my God, that would be very bad.

• 45:12Andrew D. Huberman?

  A lot of people do that. A lot of people do that. They think that, that blue light is bad. I think that the, the, the concept of blue light being bad led to a lot of product development. And a lot of people are just assuming that viewing blue light is what was giving them headaches, when in fact, it might have just been looking at screens at, at close distance.

• 45:31Speaker 07

  So here is the problem, right? I mean, the blue light got the bad reputation because people who gave a pure blue light showed that it causes usually retinal damage. But again, if you're using blue light in its pure form, it has a lot of energy because it's shorter wavelength. But we're talking about full spectrum light. There are ways now where you could change the spectrum of the light and keep it white between day and night and change the content of the color without you noticing. So you don't even have to affect your vision.

• 46:02Andrew D. Huberman?

  So how would you go about doing that?

• 46:04Speaker 07

  So you just lower the level of the blue light. You don't have to eliminate it.

• 46:08Andrew D. Huberman?

  So just dim the lights?

• 46:09Speaker 07

  Dim the blue, but keep, then increase the yellow, but keep all the colors in a certain white. So you know, you could have different warmness of white. And people know how to do this. Physicists know how to do this. People who work with light know how to do this.

• 46:24Andrew D. Huberman?

  Well, maybe somebody in the wellness slash, I don't like the word, but biohacking or optical community will do this. I think it's a really important, I see so many people wearing blue lockers.

• 46:35Speaker 07

  I don't know why, why they love.

• 46:37Andrew D. Huberman?

  Well, I think they're just uninformed. I think frankly.

• 46:39Speaker 07

  And to be honest, it's easy, right? It's easier to explain to somebody if IPRGCs respond mostly to blue, remove blue, you'll be fine, right? But that's not as simple as that because they also receive rod and cone input. So you wanna actually, and you know, we could go into details that's boring for your listeners, but it also affect the adaptation properties of the whole retina. So you don't wanna do something so drastic that you take just one color of the spectrum. It just seems very counterintuitive to me, to be honest.

• 47:09Andrew D. Huberman?

  You've told me before as well that just because these intrinsically photosensitive circadian setting, ganglion cells respond best to blue light. If the light is bright enough, because they also get input from other components of the eye, it doesn't matter if you block the blues.

• 47:27Speaker 07

  Yeah.

• 47:28Andrew D. Huberman?

  If you're looking at bright light at night, you're going to disrupt your circadian cycle.

• 47:31Speaker 07

  And, and that's why I didn't wanna go into the boring details. But themselves, the photoreceptors have a wide range of responsiveness. So they are most sensitive to blue light, but that doesn't mean they don't respond to green light or to shorter than blue light. They respond to very, very wide spectrum with different sensitivities. So unless you understand the system, just removing 480, I don't think it's gonna do.

• 47:54Andrew D. Huberman?

  480 nanometers.

• 47:55Speaker 07

  Yeah.

• 47:56Andrew D. Huberman?

  So.

• 47:58Andrew D. Huberman?

  Your home is a cave at night, basically.

• 48:01Speaker 07

  It's a nice cave.

• 48:02Andrew D. Huberman?

  It's a nice cave with candles, right? And you and your cats and your lovely wife, who I know who's also a phenomenal scientist in her own right.

• 48:12Speaker 07

  Yeah.

• 48:13Andrew D. Huberman?

  She is. And but you do keep your home quite dim to dark at night.

• 48:19Speaker 07

  In fact, I did go to to meetings with with some of my friends who work on this, and they really struggled with me. They said, we could have broken our legs living in the same light environment that you do. So I am an extreme, but I measured it for myself. And I asked Raji, my wife, if she's OK with it. She also liked the dimness. Both of us can see well in in dim conditions. And and that helps us a lot. But I think you have to measure it for yourself. You really have to do. It's a very simple experiment. Just try to dim the light as much as you can. I I call it the minimum amount of light you require to see comfortably.

• 48:57Andrew D. Huberman?

  And that's how you want your environment, ideally at night?

• 49:00Speaker 07

  This is what I think is the game changer. If you reach to a level where it's just barely, you're literally on the cusp of seeing uncomfortably versus seeing very comfortably, you are going to be very much better than. I don't like to make it completely dark. I think complete darkness induce anxiety in humans, to be honest. So I don't like complete darkness.

• 49:24Andrew D. Huberman?

  Kids don't like complete darkness. They like a night light.

• 49:27Speaker 07

  Animal, even nocturnal animals don't like complete darkness. I mean, we have studies in animals that are nocturnal that if you put them in complete darkness for several weeks, they they have severe anxiety and depression like effect. So keep the light dim. You know, use red light that is very dim if you want to keep the room for sleeping. Red light that is very dim has very small effect on on on circadian clock.

• 49:56Speaker 07

  And below ten lux of red light literally doesn't affect sleep at all. So there are ways to do it. It's just we need to educate the public. And I feel like you literally need a whole lecture to just explain to the people how to deal with light because it's not as simple as people think.

• 50:14Andrew D. Huberman?

  Well, that's what we're doing here. We're stepping through it piece by piece. And and the reason we're doing that is because it's not as simple as saying just block blue light or get a lot of light during the day.

• 50:23Speaker 07

  I mean, just to put it in perspective, to tell it, we only have three different cones in our retina that respond to three different colors. We call them red cones for simplicity, green cones and blue cones. Yet we have only three of these, but we could see massive palette of colors. So that tells you something. If the system was just simply about a single color and it's just removing four eighty or just blue is sufficient, then we should only see in red, yellow and blue. We shouldn't see all these different hues of color. But because the system is not that, we see all these different colors. And that's why it's important to remind people that the white light is made of many different colors.

• 51:08Speaker 07

  It's actually like the rainbow. That's why you see the rainbow. It's made of many colors. White light is never truly white. It's made of a lot of different colors.

• 51:16Andrew D. Huberman?

  It's like the Pink Floyd album cover.

• 51:18Speaker 07

  Exactly, exactly, exactly.

• 51:21Andrew D. Huberman?

  So dim at night, maybe dim red light ideally or candlelight. Find that minimum required light level.

• 51:29Speaker 07

  Test it. Just make sure when you lower the light, sit for at least ten to fifteen minutes. Let your system adapt. Because if you had it bright light and you switch it off, surely you're gonna suffer because your system didn't adapt it. It was used to very bright light. So you want to engage your rods, which take a long time to dark adapt. So that's why I tell you, just wait a little bit. Don't just switch it off if you don't see. Put it on, put it off, sit down, wait for ten minutes, ideally fifteen minutes, and then see how you see. And then, once you do that, you will notice that actually, yeah, I could see quite well, even with much less light.

• 52:10Andrew D. Huberman?

  What do you do regarding screens?

• 52:13Speaker 07

  Yeah, that's, that's the hardest thing. Again, I mean, there are beautiful programs that change the whole intensity and color of the screen. This could help dim your screen at night to the lowest part. I mean, yes, you won't see it when you wake up in the morning, but then you could increase the intensity. So try to decrease. I mean, just what we were talking about. Think of light, intensity, duration, color and time of day. You really have to keep these four things together, right?

• 52:41Andrew D. Huberman?

  We've roomed together at a couple of meetings from time to time. No longer, because one of us, not to be named, has a severe snoring issue that made the other one pseudo homicidal.

• 52:54Andrew D. Huberman?

  You can guess who that was.

• 52:57Andrew D. Huberman?

  But I've seen you check your phone after dark, once or twice. And you did it by sort of pointing your phone away from you, right? And, and actually, I'm sort of half joking, but I, and you dim it quite a bit. I'm sort of half joking, but it actually makes sense that, you know, if you shine a flashlight in your eye, it's much brighter than if you shine a flashlight on the back.

• 53:19Speaker 07

  Light only go in direct lines. So if you just look on the side, most of the light is gonna go this way and you're only seeing this way.

• 53:23Andrew D. Huberman?

  So you're, okay. So, and as silly as that might seem to people listening, I mean, what it means is that getting bright light in your eyes at night is something that you really want to avoid. And, but there is the reality that...

• 53:35Speaker 07

  And even when I check sometimes if I, you know, if I have something and I check it so fast and switch it off so fast. So I'm also aware of the duration. I'm also aware of the duration, right? So duration, intensity, color and time of day. Ideally, I should not check iPhones and iPads. I don't use iPad at night because it's hard to lower it enough, because it's a huge. But even my iPhone, I try not to use it at night. And like, once it becomes eight thirty or nine, I don't look at it at all.

• 54:06Andrew D. Huberman?

  Unless it's World Cup or Euro Cup, in which case Sanders on 24 hours, everybody.

• 54:10Speaker 07

  That's only every four years.

• 54:13Andrew D. Huberman?

  He's a big soccer fan. All right, this has been incredibly, no pun, illuminating. Let's talk about the relationship between light and some of these other non-circadian or pseudo-circadian effects, and we will try and link those. But you had a, what I consider absolutely landmark, beautiful paper, published in Nature a few years ago, showing that if you disrupt the exposure to light, or the timing of the exposure to light, that there are dramatic effects on the stress system and on the learning and memory system. We could talk about each of those separately or together.

• 54:57Andrew D. Huberman?

  What are the effects on stress and the effects on learning when light-viewing behavior and sleep-wake cycles are disrupted?

• 55:06Speaker 07

  Yeah. So, just to remind you, you know that, but to remind your listeners that I was trained as a circadian biologist. So I really was indoctrinated into thinking that light has to affect the clock, which then cause all these different effects. So that's what I believe, that's my dogma, that's what would have made me really happy. And then Tara Legates and Kara Ultimus joined the lab and said, and we started discussing a lot of data, and we said, what if there is a direct effect of light that we're missing, independent of the circadian clock? So this is not an easy question to ask, to answer, because as we've been talking all along, light affects the circadian clock.

• 55:46Speaker 07

  So how could you give light at different times of the day and not mess up the circadian clock? Luckily, we came up with such a way, and that's why it was important to do these experiments the way we did them. And we proved that this light-dark cycle does not disrupt the clock, there is still a circadian rhythm, and does not cause sleep deprivation. And yet... Surprisingly, if you give light at the wrong time of the day, even without disrupting the circadian clock or without causing sleep deprivation, as you mentioned, you get huge mood changes in the organisms and you get learning deficit. So this really, and at the time, people have really hit us hard.

• 56:30Speaker 07

  I mean, it was really hard to publish this work. And you could, yeah.

• 56:35Andrew D. Huberman?

  Well, it came out in Nature, so in the end you prevailed. But I want to make sure that I understand. So you're saying that, yes, there are effects of light on the circadian rhythm,

• 56:46Speaker 07

  Absolutely.

• 56:46Andrew D. Huberman?

  meaning sleep and wakefulness.

• 56:48Speaker 07

  Yes.

• 56:49Andrew D. Huberman?

  And their timing. However, there are direct effects of light on mood that can be dissociated from the effects on sleep and waking. So if I interpret that correctly, that could mean that when we view light and how much light could make us feel happier or less happy or even depressed, stressed, learning, et cetera.

• 57:12Speaker 07

  Bingo.

• 57:13Andrew D. Huberman?

  Even if we're sleeping and waking up at the appropriate time.

• 57:16Speaker 07

  Bingo. I mean, eventually, because we're talking about the whole system, eventually, when you start having the other problems, you also develop sleep problems. But you're absolutely right. And in fact, now, research from Diego Fernandez in the lab have found that now we know that they actually require different brain regions. So we don't only have a theory, we don't only have a light environment that showed they can be dissociated. We know that they use completely different brain regions. So the SCN that I told you about earlier, the place where the central pacemaker is, the one that receives direct input from the retina through the ipRGCs to adjust your circadian clock, is not the area that receives the light input for mood regulation.

• 58:00Speaker 07

  It's a completely different brain region.

• 58:02Andrew D. Huberman?

  What's the brain region called?

• 58:03Speaker 07

  So the brain region, we called it the perihypnolar nucleus. I'm not so sure how good or bad the name, but it doesn't matter, it's the PHB. And what's really amazing, this region also receives direct input from the ipRGCs but projects to areas in the brain that are known to regulate mood, including the ventral medial prefrontal cortex, which has been studied for many years to be impacted in a human depression. So just by this amazing serendipity to find that a region that is so deep in the advanced brain, like the prefrontal cortex is your executive brain, one of the most elaborated in humans, to see that

• 58:46Speaker 07

  they receive input from these ancient photoreceptor was stunning to us and told us how much we didn't understand the importance of light on a human behavior.

• 58:56Andrew D. Huberman?

  So how does that finding inform daily protocols for you or for other people? I realize you can't leap to always from one paper to daily protocols. But if light indeed does control prefrontal cortex, executive function, learning, stress, and mood. And let's say I'm waking up each morning and I'm sleeping, what should I do differently?

• 59:19Speaker 07

  That's why we came up with the tripartite model, because yes, we could think about just adjusting the clock with lights in and being dark throughout the day, but that may not be important for your whole physiological function. So now if we include these other effects of light, that's why I prefer to still get a lot of light in the day. I don't want to be in very dim light condition throughout the day.

• 59:40Andrew D. Huberman?

  I see.

• 59:41Speaker 07

  So even though it doesn't affect your clock, as you beautifully said, Andrew, it may affect your mood and learning and memory. It may affect your alertness level, which is going to allow you to learn better. It may affect your homeostatic drive. Maybe your homeostatic factor will go higher, so you could sleep earlier. So it's important to think of light as stimulating all these brain regions, which means it's producing more activity, which in reality, this is how people think of the homeostatic drive, that the more active you are, the more the homeostatic drive is built up, the better you sleep. So that's why we came up with the tripartite model, because as a circadian biologist, I only thought of light through the circadian clock affecting behavior.

• 1:00:23Speaker 07

  As a sleep biologist, they only thought of the homeostatic drive affecting sleep, affecting behavior. And for people who study light for vision and other things, they thought only of the environmental input. But now, if you put them all together, you get with this tripartite model where it's really mind boggling. And it makes so much sense. The organism doesn't want to depend on a single component. But if you could incorporate these three together, you could have a beautiful system that is well adapted. So let me tell you the sleep-wake cycle, right? So we know there is a homeostatic drive to affect sleep. You've had beautiful talks about that.

• 1:00:58Andrew D. Huberman?

  Which is basically the longer you're awake, the more you want to be asleep.

• 1:01:01Speaker 07

  So that's your homeostatic drive. We've talked about the circadian influence of sleep and the fact that light-dark cycle affect the circadian system, which eventually affects sleep. So these two components are well understood. Now, the third factor is your direct light or environmental input. How much stress, how much light you get from there also can highly impact sleep. So even if you have a good circadian and homeostatic drive, if you're getting light at the wrong time of the day, or if you're being stressed and thinking of the, then your sleep is gonna suffer. So you have to think of the three together to have a beautiful sleep-wake cycle. And that's why we came up with the tripartite model. The same thing happens with feeding. I could beautifully put it to people.

• 1:01:44Speaker 07

  Your hunger, your energy level is measured by the arcuate nucleus. Your daily intake of food is again dependent on the SCN and light-dark input. We found that if food is not available, there is yet a third input that is not dependent on the SCN, not dependent on the arcuate, depending on a completely brain, different brain regions. So the animal can actually start looking, or the human can start looking for food when it's scarce, even at time when they are not supposed to be active. So that's how the organism think they have to evaluate multiple inputs for them to decide what is the best physiological outcome at that moment, at that season.

• 1:02:24Andrew D. Huberman?

  I see. So I want to get into arcuate and feeding, but just to keep, uh, make sure we can, you know, keep our hands around this, uh, tripartite model. So if I understand correctly, we've got the circadian influence. Then you've also got the drive to sleep. Actually, one of the ways, um, that I think that can be best understood is if somebody ever pulls an all-nighter. They get tired around 11 or 12 or so, and then very tired around 3, 4 a.m. But then, even if you stay up, sometime right around 7 or 8 a.m., your normal wake-up time, you start to feel alert again.

• 1:02:57Speaker 07

  Exactly.

• 1:02:57Andrew D. Huberman?

  And that's because the sleep drive is extremely strong, but there's a circadian rhythm that drives wakefulness in the morning. Okay, so those two are the components.

• 1:03:05Speaker 07

  Right.

• 1:03:06Andrew D. Huberman?

  Before we get into the feeding component, I want to talk about these direct effects of light on mood. Okay, Diego Fernandez's data.

• 1:03:14Andrew D. Huberman?

  And this perihypnular thing.

• 1:03:16Speaker 07

  Sure.

• 1:03:16Andrew D. Huberman?

  So, let's just, for the moment, set aside the tri-part of the tripartite model and just focus on what are the direct effects of light on mood? And the way that I interpret what you've said so far is that the protocol that emerges from this, if one is trying to optimize their mood, is yes, see light, view light, I should say, early in the day in order to set your circadian clock, maybe also in the evening as well. And of course, avoid light at night, get it as dim as possible. However, you said it's also a good idea to get as much bright light during the day as you safely can in order to improve your mood independently of regulating your sleep-wake cycle.

• 1:03:56Speaker 07

  And that's a hypothesis. Here's the problem where it's not going to be as satisfying as the circadian, is that, as you know, this brain region has been discovered very recently.

• 1:04:05Andrew D. Huberman?

  Hypnula.

• 1:04:05Speaker 07

  The perihypnular.

• 1:04:06Andrew D. Huberman?

  Well, we've known about it a long time, but nobody knew what it did.

• 1:04:09Speaker 07

  So, we knew about the hypnula, but that's why the name is confusing. It's actually not the hypnula itself. It's the perihypnula.

• 1:04:15Andrew D. Huberman?

  Near the hypnula.

• 1:04:16Speaker 07

  It's near the hypnula.

• 1:04:17Andrew D. Huberman?

  Why don't you just call it the same as Hattar nucleus?

• 1:04:19Speaker 07

  I should have, I don't know why I've done that.

• 1:04:21Andrew D. Huberman?

  Maybe because if you do that, it's not okay? Okay, so for here, ever after, the perihypnular nucleus, we should probably call it the Hattar.

• 1:04:29Speaker 07

  The Hattar Fernandez.

• 1:04:30Andrew D. Huberman?

  How about Hattar Fernandez burst nucleus? Okay, this is like nerdy science attribution stuff, but I'm just going to call it the Hattar nucleus. Wikipedia, line it up. Okay, so this structure is taking light and independent of sleep rhythms, and circadian rhythms, it's driving changes in mood. How does it do that? Is this through the dopamine system? The serotonin system?

• 1:04:50Speaker 07

  We still recently, we haven't identified this region very well. We don't know. Light dust to it. We don't know how it interacts. So this is an area that is ripe for discoveries. And we're working on this right now. But that's why I said it's not satisfying. This is like the function of sleep. Why do we sleep? We know sleep is very important to us, but we still don't have a satisfying function of why do we sleep, right?

• 1:05:14Andrew D. Huberman?

  But the why questions, the why questions, I think it's our, our good friend and colleague at University of Washington, Russ Van Gelder, who always says, when somebody asks why, the, the best answer is just to say, I wasn't consulted at the design phase.

• 1:05:26Speaker 07

  Exactly.

• 1:05:26Andrew D. Huberman?

  Right? None of us really know.

• 1:05:28Speaker 07

  No, but the point is, maybe I shouldn't have said why. What is the function of sleep? It's still very hard to know. Why would, what is the reason organisms have to go offline for so long? You know, people assume it's for repair, assume it's for learning and memory, assume all kind of stuff. But there is really no clear function for sleeping. There is no clear function for sleeping. I mean, if you talk to people, there are hypotheses.

• 1:05:55Andrew D. Huberman?

  I mean, all we know is that if you don't sleep, or your sleep is very fractured, you get messed up.

• 1:05:59Speaker 07

  And you could die even, right? I mean, it's, it's really bad if you don't sleep. But we don't know, what is the function? What is the, what is that sleep have come to organisms that couldn't have done with rest? What if you just could rest without sleeping? Just sit down and rest?

• 1:06:17Andrew D. Huberman?

  Well, my, my lab is trying to figure out whether or not these non-sleep deep rest protocols can compensate for, for sleep. And I mean, obviously, sleep is better, but many people are not going, getting the sleep that they need. But, but, okay, so, and if people are sensing that Samer and I are about to start talking over each other and arguing, that's always the goal when we talk, right? Unlike other scientists I interact with, when Samer and I get together, it's considered a successful conversation if we get into a big fight and then go for a big meal where I pick the restaurant. Okay, so let's talk about food and eating and appetite. You had yet another.

• 1:06:55Andrew D. Huberman?

  Yes, I greatly admire your success in this way. Yet another incredible discovery showing that there are direct effects of light on appetite and feeding behavior. Maybe you could just summarize those results.

• 1:07:11Speaker 07

  And honestly, that paper is the one that allowed us to come with the tripartite model because we were thinking completely wrong about it. We wanted, this experiment, it'd be fun for your audience to hear why we started this experiment. Remember that when we discovered the IP RGCs, we figured if they are the only relay to entrain the circadian clock, then you could kill them and have an animal opposite to the one that we spoke, or a human opposite to the one that we spoke about early, where instead of having no pattern vision and have circadian photo entraingment, we could produce an animal that have pattern vision but no circadian photo entraingment.

• 1:07:49Andrew D. Huberman?

  So circadian blind?

• 1:07:50Speaker 07

  Circadian blind but pattern sighted. And we succeeded in that. The problem when you have these animals, which I've told you many times already, is that they don't adjust to the day night cycle. So doing experiments on them become very complicated.

• 1:08:06Andrew D. Huberman?

  What is their behavior like if you don't have these cells? Are they awake and then asleep?

• 1:08:09Speaker 07

  They just drift like the humans we've talked about.

• 1:08:12Andrew D. Huberman?

  They think they're in Las Vegas with no clocks or watch. They stay up later every night.

• 1:08:17Speaker 07

  They come either depend their clock. If their clock is shorter, they come in earlier. If their clock is longer, they come in later.

• 1:08:23Andrew D. Huberman?

  So they're really messed up.

• 1:08:24Speaker 07

  They really don't adjust to the, if they were in the wild, they'd be eliminated in a second, right? There is no way they'll survive. So me and Diego started talking and we're like, what if we use non-light entraining agent? And what is the strongest non-light entraining agent? Food. So we thought that the light defective animals will have more sensitivity to food entrainment because, as you know more than me, this is an area that you've worked really well on. For vision, if you're image blind, your hearing and somatosensory get improved, right? The lack of vision improves your hearing and sensation. But we found actually that if you don't have the light system.

• 1:09:07Speaker 07

  Actually, your feeding, the food ability to entrain the animal goes completely to the ground, completely opposite to what we predicted.

• 1:09:15Andrew D. Huberman?

  So, light viewing and feeding behavior are interacting in ways that support one another.

• 1:09:22Speaker 07

  And that's why we came with the tripartite model. We figured it's different than sensation of the environment. When you sense with vision, vision and hearing interact, but your vision is a real full modality. You want to see, that's what vision want to do. You want to hear, that's what hearing want to do. You want to sense, that's what sensing want to do. But for the circadian system, light, food, all these entraining agent, they somehow have to interact to keep a coherent system. You don't just assume if you remove light, this one is going to be stronger. No, they need to know each others. The light informs when the animal is going to eat.

• 1:09:59Andrew D. Huberman?

  Well, what I like about this so much is that, you know, in the other, in the world outside of science, in which I don't really exist in, but that I see a lot of this kind of wellness, you know, stuff with this, all this mind-body integration stuff. It's interesting because people view the body more as a system, right? A system of organs that interact as opposed to the way that standard science and medical profession is, like you work on the liver, or your ear, nose and throat, or heart and lung, or brain, or...

• 1:10:31Speaker 07

  That's a great way of thinking.

• 1:10:32Andrew D. Huberman?

  Yeah, but the biology is integrated.

• 1:10:35Speaker 07

  Yeah.

• 1:10:36Andrew D. Huberman?

  And so, for somebody who's interested in affecting their eating behavior, something that you are familiar with and that we will talk more about your experiences of in a moment, how should they use light in order to adjust their eating behavior?

• 1:10:53Speaker 07

  Right. So now that I've told you about all these interactions between the different inputs to the circadian clock. Just you think about it as an engineer, what would be the best thing? The best thing is to know when your food times happen in the day, when should you get light? And where is your circadian, when is your circadian clock in your system? Right? So if you eat at very specific times of the day, that's another signal that is telling your body, your clock, you're in a certain time of the day. So if you're having lunch at the correct time every day and you're getting bright light, now you have two systems that are informing your clock. Your clock is gonna be better.

• 1:11:32Andrew D. Huberman?

  So regular mealtimes?

• 1:11:34Speaker 07

  Regular mealtimes that fit your circadian clock. So and in fact, if you do that, when, when I started doing this and it helped me lose weight, is that I'm exposing myself to the right amount of light/dark cycle. I'm eating at regular time. It is amazing. You will be not hungry, let's say, let's say you eat at noon. You will not feel any hunger at eleven forty-five. And then all of a sudden, the hunger jumps. This is clearly not an energy issue because it could not be that drastic.

• 1:12:02Andrew D. Huberman?

  Right, no, the desire to eat is mainly driven by these, these cues, these hormone cues that are very exquisitely timed to

• 1:12:12Speaker 07

  Exactly.

• 1:12:13Andrew D. Huberman?

  sleep-wake cycle, but also to light.

• 1:12:15Speaker 07

  Exactly. And you know, in the wild, you could imagine why energy level through the arcuate nucleus.

• 1:12:21Andrew D. Huberman?

  You should explain to people what the arcuate is because I don't think we've done that adequately. The arcuate nucleus is an area of the hypothalamus that drives hunger and feeding behavior. And what we're talking about is the fact that it's taking cues from your viewing of light, believe it or not, is impacting your level of hunger. And this is a, a non-trivial way in which your timing of hunger and amount of hunger is regulated by when and how much light you view. So let me ask you a couple of practices.

• 1:12:51Speaker 07

  Can I just, this is really, before you ask me, sorry, Andrew, we said we're gonna fight. But to me, is, is the, the interesting thing to think about it, in the wild, when you didn't have the availability of food that we have, the arcuate plays a huge, important role. Because if you're not, if you weren't successful in getting food. Then the ark is gonna tell you, look, you have to take risk and go get food because your energy level is very low. And that's great. That's tons of great research about that. But I think what's missing is the fact in humans, we're not getting to a situation, most of us, we're not getting to a situation where we have low energy levels. Most of the time, actually, we eat not because we want to, because we are really have low energy,

• 1:13:34Speaker 07

  but because we wanna eat. So I think that's why I feel that the timing is very important for us, because we always have enough energy level for us to eat.

• 1:13:44Andrew D. Huberman?

  Well, I mean, I enjoy eating so much that I'll eat just for the sensation of chewing.

• 1:13:48Speaker 07

  True.

• 1:13:48Andrew D. Huberman?

  I mean, I I enjoy the taste, too.

• 1:13:50Speaker 07

  True.

• 1:13:51Andrew D. Huberman?

  And I enjoy the social aspects when those are a part of it. But I I literally enjoy the physical act of chewing.

• 1:13:57Speaker 07

  Absolutely.

• 1:13:58Andrew D. Huberman?

  Uh huh. Which explains a lot. Um, okay, so how regular are you, or do you recommend people be about mealtimes? Because what I'm hearing is that light viewing behavior is pretty straightforward. Get a lot of light in the morning and throughout the day, minimize it in the evening and at night, generally speaking, for sake of mood and circadian rhythm. But for sake of regulating timing and quality, I should also say of food intake, because people clearly make better choices about food intake when they are anticipating a meal and they aren't constantly hungry. And so the ability to regulate hunger for particular phases of the circadian cycle is is quite valuable for all people, not just people trying to lose weight, but all

• 1:14:43Andrew D. Huberman?

  people. Are we talking about down to the minute? Like,

• 1:14:47Speaker 07

  Absolutely not.

• 1:14:48Andrew D. Huberman?

  All right. Plus, so twelve noon is my normal lunch, let's say, plus or minus?

• 1:14:54Speaker 07

  Half an hour.

• 1:14:55Andrew D. Huberman?

  Okay.

• 1:14:55Speaker 07

  Yeah.

• 1:14:56Andrew D. Huberman?

  So eat around between eleven thirty and twelve thirty.

• 1:14:58Speaker 07

  If if that's the time. And it depends if you also do multiple meals. Remember, three meals, that's a decision that somebody came up with. I don't know why.

• 1:15:07Andrew D. Huberman?

  Nowadays, people are fewer people are doing that, I think.

• 1:15:09Speaker 07

  Yeah.

• 1:15:10Andrew D. Huberman?

  Given our friend Sachin Panda's work.

• 1:15:12Speaker 07

  Right. I mean, so you could have two meals, you could have. Very, multiple meals that are distributed across your active time. I, I agree with Sachin Panda's work that try to avoid eating when your system is supposed to be relaxing, when you're supposed to be at non-active times. So, you know, limit your eating to the active time of your, of your cycle. And that seemed to be, and Joe Takash is doing some beautiful stuff on this. That seems to be incredibly important for aspect of the circadian.

• 1:15:46Andrew D. Huberman?

  And for health.

• 1:15:47Speaker 07

  And for health.

• 1:15:47Andrew D. Huberman?

  Yeah, I mean, Sachin, we're referring to Sachin Panda's work. He wrote a beautiful book called The Circadian Code. Maybe Samer with, with some luck, you'll write a book as well, meaning the world would be lucky to have that book. But Sachin's data really strongly points to the fact that liver health, brain health, metabolic factors and endocrine factors and various systems and organs all seem to benefit from having a period of each 24-hour day in which we are not eating anything and then eating at very regular mealtimes. Let's talk about eating and mealtimes and let's move a little bit away from the, the science for the moment, although we will return to it, and talk a little bit more about your experience with eating and mealtimes.

• 1:16:31Andrew D. Huberman?

  So, you're looking in good shape lately.

• 1:16:34Speaker 07

  Thank you.

• 1:16:34Andrew D. Huberman?

  I know you've been putting work into it.

• 1:16:36Speaker 07

  Yeah.

• 1:16:36Andrew D. Huberman?

  We talk a lot and you've been exercising and you've been eating well, meaning quality food. You just came back from Jordan where I'm assuming the food is amazing.

• 1:16:46Speaker 07

  It's, the food is amazing and honestly, usually I gained a lot of weight in Jordan, but this time I didn't gain any weight, which was really nice, so.

• 1:16:54Andrew D. Huberman?

  Yeah, you've, you've, when I met you, you were probably about 100 pounds heavier than you are now.

• 1:17:02Speaker 07

  Yeah, 275 pounds, I'm 219 now, that's crazy, yeah.

• 1:17:06Andrew D. Huberman?

  You had a lot of vigor then and you have a lot of vigor now, but I know that you undertook a very specific protocol in order to lose the weight. Based on your understanding of the circadian system and of light and appetite and mood. Uh, maybe you could just tell us a little bit about what that schedule looks like. And we realize that this is not a prescriptive for everybody, but you found what worked for you.

• 1:17:30Speaker 07

  Yeah.

• 1:17:30Andrew D. Huberman?

  Maybe just describe those.

• 1:17:31Speaker 07

  I mean, honestly, I followed my circadian cycle, right? Of what we've talked about, right? So I dim the light at night, I slept at regular hours. I ate my major food in breakfast and lunch when I'm really active and I'm really hungry. And at night, when I avoid dinner, because my circadian system really shuts off at three. I'm an early person. Like, you could give me anything, I would eat before three. After three, nothing appeals to me anymore. My system is shut off.

• 1:17:59Andrew D. Huberman?

  But what time are you going to sleep and what time are you waking up?

• 1:18:01Speaker 07

  In my case, I should have put this on. I mean, I go to sleep literally at nine a, nine P M. I mean, I literally, five minutes after nine P M, I'm completely out. And I wake up between four thirty and five A M. So if I extended, I go to six A M. But very rarely, it depends on how tired I was.

• 1:18:19Andrew D. Huberman?

  And that, as I recall, was an important set of changes for you to be able to regulate your food intake.

• 1:18:25Speaker 07

  Absolutely, because then I'm having very big breakfast at, and again, for different people, it's different. I have a big breakfast at seven A M maximum. So I have a big breakfast, coffee and all this stuff. Then I have some simple snack around ten. Then I have regularly lunch at noon or between noon to one. Then I have another snack at three. And the hardest time to regulate the food is between twelve and three. This is when I'm, I really feel hungry all the time.

• 1:18:53Andrew D. Huberman?

  This is your equivalent of kind of late evening for most people. So for me, it would probably be between seven and ten P M.

• 1:18:57Speaker 07

  Exactly, exactly. And then at night, I'm, I'm completely not hungry. But usually, as you said, the beauty, the, the enjoyment of food, like when my wife kicks, cooks some really beautiful Indian food, I eat, but I'm not hungry. And I notice if I eat with that, I usually gain weight. But if I regulate that at night, I also lose weight. So there is a combination of all these things that help you adjust these, this, the, the, the input of food, the input of light, the input of the clock, and the drive to hunger.

• 1:19:28Andrew D. Huberman?

  Yeah, I appreciate you sharing that. And I want to emphasize that some people are not hungry early in the day. They might be late shifted people. In which case, eating later in the day will work well for them.

• 1:19:38Speaker 07

  Work as long as they don't eat early in the morning. That's just you have to work with your schedule, with your active schedule.

• 1:19:44Andrew D. Huberman?

  Yeah, you and I have been talking about this offline for years. I'm glad we're finally having this discussion publicly now. What we're talking about really is finding your ideal sleep schedule.

• 1:19:52Speaker 07

  Exactly.

• 1:19:53Andrew D. Huberman?

  And finding your ideal eating schedule.

• 1:19:56Speaker 07

  Exactly.

• 1:19:56Andrew D. Huberman?

  And understanding how those two things interact.

• 1:19:59Speaker 07

  And you know, the nice thing, as you said, finding them out is going to help you to understand how they interact. Because we know from the tripartite model that they are all interconnected. And for each person, they're going to be interconnected differently. So for each person, you would, you know, for me, if I exercise at night, I'm going to mess up my whole system.

• 1:20:20Andrew D. Huberman?

  So when do you exercise?

• 1:20:21Speaker 07

  Morning. Morning works great for me. I mean, it's amazing. Morning exercise for me works great. If I tried one time because it was easier for me to exercise at night before I leave when the traffic is there from the nation, I think that messed me up because I couldn't sleep well and I couldn't wake up well and that led to more changes in my food. I gained weight again, actually. Believe it or not, even though I was exercising. So I think this really makes me think that you have to think of the tripartite model to see where is the best times and what is the best interrelation between the different component, as you beautifully said, between your meal times, your light exposure and your sleep that works for you.

• 1:21:03Andrew D. Huberman?

  Well, thank you for that. Usually Sam is insulting me. Today, he's complimenting me. I'm going to compliment him right back by saying, this is the first time that I've ever really understood how, yes, light can control sleep. Yes, it can control mood. Yes, it can impact feeding, but that it's really about doing the self-exploration to align those in the way that works best. And what I'm hearing, tell me if I'm wrong, but what I'm hearing is that, once you understand what gives you the best sleep-wake cycle, then you should exercise during the period of time in which you feel most alert. And if it works for your schedule, ideally, you would also eat during the time in which you feel most

• 1:21:46Andrew D. Huberman?

  alert, and then stop eating and stop light-viewing behaviors as you head towards sleep.

• 1:21:51Speaker 07

  Right. So, the only thing I would say that complicates all of this, and that's what makes me sad, is your light exposure.

• 1:21:58Andrew D. Huberman?

  Mine personally?

• 1:21:58Speaker 07

  Sorry.

• 1:21:59Andrew D. Huberman?

  No, I'm just kidding.

• 1:22:00Speaker 07

  The people's light exposure, right? This is what complicates it, because you're not going to be able to figure all this out if you're shifting yourself out of your comfort zone.

• 1:22:10Andrew D. Huberman?

  By viewing?

• 1:22:11Speaker 07

  By viewing light at the wrong time of the day. So, let's say, let's say you're, if you were under an idle, natural conditions, you're a person who would sleep later than me, let's say, will sleep at midnight and wake up at 8:00 a.m. Let's say you don't eat anything till noon, and as you said, you eat late in the evening. Then, this would be perfect for you. But now, see what happens if now you include the light component. Now, if you push your sleep from midnight to 4:00 a.m., now you're waking up in the morning, and you're actually really not the morning, you're waking up, sorry, at noon instead of 8 o'clock, and the time where you're not supposed to be hungry, now you're going to start eating directly at noon, or something like that, or even delay it. And now you're

• 1:22:55Speaker 07

  shifting your whole cycle, and you don't know if this interaction between your sleep, feeding, and the light-dark environment are still going to be maintained or not. And that's the problem that people have.

• 1:23:05Andrew D. Huberman?

  So, most, you know, as I'm hearing this, what I'm realizing is, most of us, probably me included, are messing up at least one, two, or three of these components.

• 1:23:14Speaker 07

  Exactly.

• 1:23:15Andrew D. Huberman?

  But that the, that the probe, the way to, to figure out what's right for oneself, is to start manipulating light exposure.

• 1:23:23Speaker 07

  Right. And I'm, I'm gonna be honest, I'm biased, because I believe that light is the stronger, is the strongest time giver. And we, a lot of people disagree. Some people think feeding is.

• 1:23:34Andrew D. Huberman?

  I always thought that light was the primary zeitgeber, the primary...

• 1:23:37Speaker 07

  Yeah, but a lot of people think it's food. A lot of people even sometimes mention social interactions.

• 1:23:41Andrew D. Huberman?

  They read the literature?

• 1:23:42Speaker 07

  I I agree with you. I I totally agree with you.

• 1:23:45Andrew D. Huberman?

  I mean, my understanding is that light is the most powerful driver of the things we're talking about.

• 1:23:49Speaker 07

  That's why I think we need to regulate this first and everything else fits. And you know, the nice thing is that your sleep-wake cycle and exercise tell you really bluntly if you're doing it right or not.

• 1:24:00Andrew D. Huberman?

  Tell me more about that.

• 1:24:01Speaker 07

  I'll tell you more. When I shifted my exercise, honestly, things fell apart like never before.

• 1:24:07Andrew D. Huberman?

  When you moved from exercising early in the day to late in the day?

• 1:24:10Speaker 07

  Yeah, it completely fell apart for me. I didn't enjoy exercise at night. My pain tolerance for exercise wasn't as good. I'm talking with N equals one, and I'm aware of this. I've never tested this empirically. But at least to me, it really messed up everything. I started having problems because my body temperature would go up, and that will affect my sleep. I possibly was running in the gym with a lot of lights, so maybe the light was a component. But for me, exercising in the morning, it's so much better for me. But a lot of people can't even think of exercising in the morning. So it depends on when you feel comfortable in your sleep-wake cycle and your exercise. I think that tells you if your system is in synchrony with one another.

• 1:24:51Andrew D. Huberman?

  That's really interesting. You know, I, we're good friends, our our friend Pat Dossett, right, that we both know, you know, did nine years in the SEAL teams, and he's one of these people. Says, you know, he's happy to go for a run or swim anytime between four thirty AM and six AM. And he'll train in the afternoon, too, because, you know, he's a SEAL Team guy, and they'll do whatever anytime. That's part of the phenotype. But he feels best doing that, right? I'm a mid, I like to exercise mid-morning, and I'm happy to skip eating until twelve or one.

• 1:25:20Speaker 07

  Great.

• 1:25:21Andrew D. Huberman?

  And I like to go to sleep around eleven thirty, twelve, because I'm a normal human being rather than you, who goes to bed at nine PM.

• 1:25:26Speaker 07

  What about Pat, actually? I've never asked him what time.

• 1:25:29Andrew D. Huberman?

  So Pat's ideal to sleep time, I've asked him, this would be around eight thirty or nine, except now. No, but he has, yes, but he has two young children, two years old and a newborn, and so the cycle is disrupted.

• 1:25:42Speaker 07

  Yeah, but that's known, right? I mean, the the effect of childbearing, and I think there, we could talk about this, that's more complicated. But that's pretty, pretty much, yeah.

• 1:25:52Andrew D. Huberman?

  Yeah, I mean, I think we need to come up with a new name for chronotype, because chronotype implies that it's just about sleep and wake, being an early bird or a night owl. And what we're also talking about is how exercise and eating match on to those.

• 1:26:06Speaker 07

  And the phase relation between them.

• 1:26:09Speaker 07

  And the phases between different components, as you said.

• 1:26:12Andrew D. Huberman?

  Because they interact.

• 1:26:13Speaker 07

  Because they interact. And they don't have to be in the same phase, like, let's say my light and food could be very close to each other's. Your light and food could be different, right? The phases don't have to be, they can be plastic, so you have to find this for yourself. You may, you may be a person who eats late at night, exercises late at night, or you may be a person who exercises early, eat later, so it doesn't, as long as the phase is, is good, that's what you, that's what you have to find out.

• 1:26:40Andrew D. Huberman?

  Okay, and if I understand correctly, when you're talking about phase relationship, it means you want to lump exercise, feeding and light for.

• 1:26:47Speaker 07

  And sleep.

• 1:26:47Andrew D. Huberman?

  And sleep, in a way that, as a coherent and total system, makes you feel really good.

• 1:26:54Speaker 07

  Temporarily in a great order.

• 1:26:56Andrew D. Huberman?

  Uh huh.

• 1:26:56Speaker 07

  Absolutely.

• 1:26:57Andrew D. Huberman?

  Yeah, that's, and I think that.

• 1:26:59Speaker 07

  And I could tell you, to me, is literally getting exposed to sun, you know, clearly in the morning, clearly at noon, I go out, I keep my windows in the office completely open, eating mostly in the early time of the day and exercising, and literally at the end part of the day, I'm literally in a more thoughtful, vegetative state, like, I really can't, like, after five, I tell my students, if you want to tell me anything complicated, you're wasting your time. My brain just doesn't function. So even though I only sleep at night, but I'm really starting to shut off, ramp down. Really, I mean, it's, you know, I could send the email, talk about brainless stuff,

• 1:27:39Speaker 07

  but my power, my energy to, to do powerful stuff, really dropped tremendously. So all my students who know me very well, they put the meetings with me early in the morning, because they know this is when I'm, so everything for me, and for me, is very tight. So it could be different from, it's very clustered in the morning, it's all tied together, and literally the remaining part seems to be just a, you know, vegetative state.

• 1:28:04Andrew D. Huberman?

  Yeah, you and my bulldog Costello, who unfortunately passed away recently, had that in.

• 1:28:10Speaker 07

  I did not.

• 1:28:11Andrew D. Huberman?

  Sam and Costello were good friends. Yeah, sorry to break it to you here. Yeah, he had a good, long life and he went easy, but he had a circadian clock that basically would just sleep around 24 hours a day, minimal activity interspersed every third day or so. You do have this morning vigor.

• 1:28:28Speaker 07

  Yes.

• 1:28:29Andrew D. Huberman?

  And that I'm that I think other people are going to have more of an afternoon vigor. Do you think that this can change across the lifespan? It's the rumor is that teenagers naturally want to sleep in later and stay up later. Do you think that's social rhythm? Or do you think that that's actually biological?

• 1:28:45Speaker 07

  Yeah, that's a tough question. I mean, it could be both. One thing that worries me is that it seems that if anything with age, this morning rigor gets stronger.

• 1:28:57Andrew D. Huberman?

  You mean, you want people to become more of morning people?

• 1:28:59Speaker 07

  More of morning.

• 1:29:00Andrew D. Huberman?

  Why is that? Were you? I think that's good.

• 1:29:02Speaker 07

  Because for me, I'm already a very shifted morning. I don't want to be one of these 7:00 PM to 1:00 AM sleepers at some point.

• 1:29:08Andrew D. Huberman?

  On the other hand, it's also kind of nice because it's quiet and you can get work done.

• 1:29:12Speaker 07

  Yeah, but honestly, from 4:30 till 7:30, when my wife wake up, it's it can be very lonely. Yes, you achieve a lot, but it's quiet outside. It's, you know, so I don't want to be at 1:00 AM. Let's put it this way.

• 1:29:26Andrew D. Huberman?

  You can tell Sam is more social than I am.

• 1:29:28Speaker 07

  That's right. That is true.

• 1:29:30Andrew D. Huberman?

  But we should touch on that, actually. So your wife is she follows a different schedule?

• 1:29:35Speaker 07

  Yeah.

• 1:29:35Andrew D. Huberman?

  And so the social rhythm is important. I think what should we do? How should we conceptualize? And how should we adjust ourselves according to the social rhythm?

• 1:29:45Speaker 07

  I honestly love this hypothesis that people came up with and Pat's kids reminded me of. Because kids are really gonna disrupt your sleep cycle. It seems like there is a. Chrono attraction that usually people who attract each others have actually different sleep-wake schedule. And the idea being is that this allows them to take care of their kids throughout the day/night cycle.

• 1:30:10Andrew D. Huberman?

  And have a peaceful marriage.

• 1:30:11Speaker 07

  And have a peaceful marriage in a way, right? So, I mean, we didn't have kids, me and Raja, so maybe this is, but it seems like evolutionary, it makes sense that if you wanna protect your, protect your kids, you don't want everybody to be morning rigor and then the kids don't have, so you want the distributed echoes. I, it makes sense.

• 1:30:29Andrew D. Huberman?

  It's a reasonable argument. I've heard that one of the reasons that people think that the clock is not exactly 24 hours, but is 24 hours plus or minus, you know, 20 minutes or so, is because we believe that we evolved in clans or groups, villages, whatever, that were about 100 to 200 people. And in order to have protection around the early morning hours when we're vulnerable to predation, and in the late night hours, that you would want some individuals of, of our species to be naturally more like night owls and some more like early people. So your, um, theory of parenting is, um, is similar in that way.

• 1:31:08Speaker 07

  Right.

• 1:31:09Andrew D. Huberman?

  The social rhythm is, is a powerful rhythm, though. Meaning, if I go out and I'm tired, let, let's say I'm tired at like 9:30, I don't wanna go out, like I'm in a meeting.

• 1:31:18Speaker 07

  Can I just say something about that? I think the social rhythm is powerful at the obvious levels, like it affects your sleep, it affects how much you wake up or eat, but I'm not so sure it's as powerful as people think on the clock. Now, eventually, it will mess up the clock, because now if you're doing a lot of social at night, getting enough light, eating at the wrong time of the day, eventually, you're gonna have an effect. But I don't think that's the social interactions themselves have been shown to affect your clock very strongly, for some reason.

• 1:31:50Andrew D. Huberman?

  That's good to know. Well, um, for people hearing this, they're probably getting the impression, like, I'm the night owl, and then Samer is the one that's in bed at nine, and then, uh, you know, wakes up at four, but having attended many meetings with Samer, I can tell you that he's the party animal. So, let's talk about that. I mean, let's talk about the fact that you're the, the partier who's up until two, dancing at these, at these various meetings, which I've seen.

• 1:32:15Speaker 07

  Yeah.

• 1:32:16Andrew D. Huberman?

  Actually a good dancer, I'm told, but.

• 1:32:20Andrew D. Huberman?

  What should we do when we do stay up very late? For whatever reason, could be because we had to take a midnight trip to the hospital, unfortunate reason, or it could be because you're in the presence of people that you don't see very often and you go out for a really nice night out on the town and you get to sleep around 2:30 or 3:00 in the morning. How should one get back on schedule? Do you force yourself to then get up and view light at the normal time that you would get up and view light? Or do you allow yourself to sleep in? What's the optimal?

• 1:32:49Speaker 07

  I would allow myself to sleep in and remember, this is a long-term effect. This is something that you live with for a long period. And remember, I told you about the experiments we did with the mood. These require two weeks of that light schedule to cause mood disturbances. So these don't happen just in a single day.

• 1:33:05Andrew D. Huberman?

  So this is the way you justify staying out late every once in a while?

• 1:33:08Speaker 07

  Well, in the meetings, you've seen me, and I've done this for five or six days continuously. But what you didn't see that when I came back to my home, it took me two weeks, as if I did a jet lag. So I really do suffer for two weeks after doing a sick crazy night of staying up at night, drinking at the wrong time of the day. So it's not that I'm completely okay with it. When I go back, everything goes back. It takes me actually literally two weeks to recover from the circadian rhythm meeting that you've seen me partying at some point.

• 1:33:38Andrew D. Huberman?

  Which is kind of ironic, the circadian rhythm meeting. People are totally disrupting the circadian cycle, but scientists are human beings too.

• 1:33:45Speaker 07

  Right. So I think if you do it at very little occasions, I think you should not worry too much that this will have a lasting impact. And the good news is that if you readjust your schedule, you could come back to it. The problem is, when you maintain these wrong schedules for prolonged time and it becomes chronic, prolonged periods of time, that's when you have the problems and the accumulation of the problems. So when you have sleeping problem, you produce metabolic problem. When you have metabolic problems, you produce lack of exercise and you could see how things can spiral out very quickly and then it would be hard to come back to it.

• 1:34:24Andrew D. Huberman?

  Well, certainly, sleep disruption is both a symptom of and

• 1:34:27Speaker 07

  Yes.

• 1:34:28Andrew D. Huberman?

  a cause of almost all

• 1:34:30Speaker 07

  Absolutely.

• 1:34:30Andrew D. Huberman?

  mental health disorders.

• 1:34:32Speaker 07

  Absolutely.

• 1:34:32Andrew D. Huberman?

  Right? And certainly, the metabolic syndromes that people are talking about nowadays and all of this, it all funnels back to light. This is what's so remarkable.

• 1:34:42Speaker 07

  Yes.

• 1:34:43Andrew D. Huberman?

  And so we have these devices and I use my phone and I use my computer. But do you think that the mere dimming of the screen or not interacting with screens after, you know, with say 90 minutes or two hours before bedtime, according to what we're saying today, this should have a profound effect on all these

• 1:35:05Speaker 07

  And it does. And I really believe it does. And I, you know, I, again, I, I think as Pat has did these, these, these inventions where you get a pouch, where you put your phone in a pouch.

• 1:35:15Andrew D. Huberman?

  So what Sam is referring to is our friend Pat, this former SEAL Team member that we, that who's also a very impressive person in the landscape of business and family, et cetera, real a superhuman from by any regard, has this habit of taking his phone and putting it into a sealed pouch in the evening. So it's basically

• 1:35:35Speaker 07

  And in his program, he sends you actually these, these sealed, you know, patches. And, so that I think is, is a great idea because not only it will take away the light from you, but it also take away the distraction because you wanna repair and recover and sleep does that. And if you have your phone dinging all the time or, or the light flashing from it, it's you're just not getting enough sleep and you're causing yourself major problems.

• 1:36:01Andrew D. Huberman?

  I never asked you this, but I, I realize now that I, I should have long ago, but I'll ask you now, why and how did you get into all this stuff?

• 1:36:14Speaker 07

  Yeah. I mean, honestly, I, I, first of all, I wanted to become a, you know, I wanted to study genetics and I knew I wanted to do PhD in genetics. But I only got accepted in one university at the time and I joined the learning and memory lab. And I liked learning and memory. At the beginning, I worked on the snails on Aplegia carifonica and, and started looking at learning and memory. But then the same lab was looking at these daily variations. I was really struck, like you never think about it outside of science. It really struck me that organisms can measure day.

• 1:36:49Speaker 07

  Biologically, that was very shocking to me and I just really got attracted and I wanted to see, why does this happen? What is the effect of different times of day? And I just stuck with it. It's just, it was mind blowing for me who was in medical school that I've never heard about it before. You know, it's really amazing, medicine, I think still now, we are very good at looking at stuff spatially, but we're very bad at looking at temporal aspects. So we always, you know, like to see images, static images, spatial information.

• 1:37:22Andrew D. Huberman?

  Take an X-ray, measure a temperature, measure a blood pressure.

• 1:37:25Speaker 07

  Exactly, but we don't think of temporal. And, and you know, you talk to John Huguenash right now and he's telling you the importance of chrono medicine or chrono pharma- pharma- whatever the word is. And it's just, it really just getting the, the drugs at the right time of the day is gonna be essential for our health.

• 1:37:43Andrew D. Huberman?

  Do you think that's gonna come from using better trackers like, um, Oura rings, Whoop straps, these kinds of things?

• 1:37:50Speaker 07

  I, I love the trackers, but I think there's even more exciting discoveries. Now you could take a single blood sample and measure many biological components and figure where you are in the circadian clock, something that was very hard to do before. So if you have a marker to know where you are in the clock, you could actually understand more the effect of everything, exercise, feeding, light input.

• 1:38:11Andrew D. Huberman?

  What is the marker?

• 1:38:12Speaker 07

  So there are some papers from, uh, uh, what's her name, Phyllis Z and from, um, Akim Kramer, where they measure multiple RNAs that are known to tell you what phase of the clock is or multiple, uh, proteins or biological reactions. And depending on a combination of factor, not a single factor, you could tell where you are in the circadian clock. So they could, instead of just measuring temperature or melatonin, just one measurement. And melatonin specifically is also complicated by the fact that melatonin is affected by light. And you know, and temperature, your temperature and sleep can be easily dissociatable, right? When you travel across different times on your sleep at different times in the temperature cycle.

• 1:38:56Speaker 07

  So having multiple components measured will give you a better determination of your circadian phase. And understanding your circadian phase in humans will tell you what is the effect of giving certain drugs at certain times of the circadian phase. So in the future, this is going to be studied at a much higher level when you can determine the phase in relation to all the other stuff.

• 1:39:19Andrew D. Huberman?

  It's striking to me that in all animals besides humans, if they deviate too much from the appropriate exposure to light and light dark cycle, they essentially don't mate and or die and or get killed off. But in humans, we are able to override that at least to some extent. But the ways in which we suffer appear to be things like obesity, metabolic syndromes, reproductive syndromes that accompany the other syndromes, you know, endocrine syndromes, and mood and depressive disorders. Is there any effort at the level of the, nationally or laboratories that you're aware

• 1:40:00Andrew D. Huberman?

  of, to try and use light in order to improve mood and mental health?

• 1:40:05Speaker 07

  I mean, honestly, this is my mantra. This is the thing that I think people, because it's, I, I, I say, don't take a pill, take a photon. And not, I mean, you take pills, it's important. I'm just making it that really we have an opportunity right now with the incredible advances of LED lights, of changing spectra of light, of regulating intensities. And just to, just for simple changes, you could really improve sleep-wake cycle, productivity, and still you could actually get more done. Because as we've talked about, when you have all these messed up, now you have to sleep more, but your sleep is fragmented, it's not very good.

• 1:40:47Andrew D. Huberman?

  And you can't focus.

• 1:40:48Speaker 07

  And you can't focus, you don't have alertness when you need the alertness. So having all these, you could allow you to do even more, actually, at the end than less. And that's the exciting part of it.

• 1:41:01Andrew D. Huberman?

  One of the questions I get asked most often about is about ADHD. You know, I think there's a lot of self-prescribed as well as clinically prescribed ADHD. People are having a tremendously difficult time focusing and not just because they're sleepy. They just can't seem to anchor their attention. And there could be multiple reasons for this, but there are now several clinical trials ongoing using light to try and anchor people's attention and mood and wellbeing for sake of focus. And I think that while I love this saying that you mentioned, you know, take a photon, not a pill. And with due respect to the need for pharmacology for certain people. I think most people just haven't really dialed in their relationship to light in a way that allows them to rule out whether or not they need medication.

• 1:41:43Speaker 07

  Absolutely. Absolutely. That's the best way to put it. I can't add to that.

• 1:41:47Andrew D. Huberman?

  Let's talk about jet lag, but not in the context of, okay, if somebody's traveling from Europe to Japan or from the east coast, because that varies tremendously, right? I mean, there's as many different variations on travel as there are individuals out there and with goals and jobs, et cetera. But rather, let's talk about what are the two or three things that people can do to adjust their schedule quickly? Yesterday I called you and said, look, I know somebody who's traveling six hours. I won't even mention in which direction because I don't want people to anchor to that example. And you described some very simple tools of viewing light a little bit earlier than normal

• 1:42:28Andrew D. Huberman?

  and getting on the local food schedule, et cetera, that would allow them to shift more quickly. And the reason I want to have this conversation is yes, for the travelers and for the shift workers, but mostly because of the fact that you've proven again and again that people are disrupted in their circadian behavior at home. So what are the, aside from what we've already talked about, how can one adjust quickly to a new schedule? Like, let's say fall classes are starting. You start a new job or you have a baby or a puppy or whatever. What is the best way to shift the clock quickly?

• 1:43:03Speaker 07

  So it's very simple, as we've talked yesterday. So imagine you're in the outside with no environmental, with no industrial light.

• 1:43:12Speaker 07

  If you, if your body thinks you're in early evening and you see a bright light, what does this tell you? Oh, wait, this is not early evening yet. It's still early afternoon or late afternoon. So I have to delay my clock to go back to late afternoon. So if you get light early in the evening, it delays your clock. So what does

• 1:43:33Andrew D. Huberman?

  Meaning that makes you wanna go to sleep later?

• 1:43:35Speaker 07

  Yes, it delays your clock. So, so you're in New York, right? People in Italy have an advanced clock because they, they are six hours ahead of us. So if you're in New York and you get light early in the evening, you're delaying even further from Italy. So now you're delaying away from Italy. Now the same thing happens. Let's say you thought dawn came up and you thought it's already dawn, but it was, let's say, three o'clock in the morning or four o'clock in the morning. And then you get a bright light and you say, oh, wait a minute, dawn is not up yet, so I should advance my clock. Or I'm, I'm at night, but I'm getting bright light. So I should run because dawn is already up.

• 1:44:17Speaker 07

  So then later in the night, later in your night, and actually it just happens that in humans you get a temperature in the deer later in the night, low temperature in your body. After that, lights start advancing your clock. So if you wanna go to Italy instead of getting light early in the evening, you wanna get light after the temperature low. So you could advance your clock even before you go to Italy. And you're catching up to the Italians just by using light. It's as simple as that.

• 1:44:47Andrew D. Huberman?

  Great.

• 1:44:47Speaker 07

  So you could do it for every region. You could calculate how much they are advanced of you. You could know how much these light shifts happen per day. And you can calculate what you, what you need to do, very simple math, to adjust either in direction of delaying. If you're going from New York to California, you wanna delay your clock or advancing if you're going from New York to Italy.

• 1:45:09Andrew D. Huberman?

  So in order to make that a visual, and because a lot of people are listening to this, not looking at it on video, we will, we will put a, a down, a zero cost downloadable uh, figure of this on the hubermanlab.com website related to this episode. But I think I can summarize it in, um, in language as well. If I understand correctly, what you're saying is if your typical wake up time is, say, seven AM, then your low point in temperature probably occurs somewhere around five AM. And if you view light right about around then, it's going to essentially advance your clock.

• 1:45:44Speaker 07

  Yeah, because then your your body thinks, oh, it's seven o'clock. So advance your clock by one to two hours.

• 1:45:50Andrew D. Huberman?

  But if I were to view light, say, at 3 a.m., then it would probably delay my clock.

• 1:45:55Speaker 07

  Yeah.

• 1:45:56Andrew D. Huberman?

  Okay. Yeah. So and then let's say I land in a new schedule. I want to adjust to a new schedule. Let's say I didn't manage to do anything with my light viewing before I went and I didn't I didn't anticipate the trip. Suddenly, I'm on a new schedule. Okay. I was told that one of the ways to help shift the clock and to avoid gastrointestinal issues is to eat on the local schedule. To start basically behaving like a local, even though your circadian clock will take a little bit of time to catch up.

• 1:46:25Speaker 07

  Absolutely. But you have to remember the light, right? So let's let's now that we explained it very simply, let's take a very simple example, right? New York to Italy. That's a simple example. New York time, Italy time, six hour difference, right? So let's say you fly from New York at night, you reach Italy at eight o'clock in the morning. What is the time in your New York time? Although you reach.

• 1:46:48Andrew D. Huberman?

  Six hours back.

• 1:46:49Speaker 07

  Six hours back. It's 2 a.m. So when you land Italy, you want to avoid light like the plague. Yeah, you could eat, but you really don't want to get a light.

• 1:46:57Andrew D. Huberman?

  Right, because otherwise it's going to delay.

• 1:46:59Speaker 07

  It's gonna delay you. It's gonna send you to California instead of sending you to Italy.

• 1:47:02Andrew D. Huberman?

  Right. And so this is such a key point. If anyone's confused about this, we will put some diagrams up. But what Sam was saying is so crucial. Just because getting bright light in your eyes early in the day is really beneficial when you're at home. When you travel to a new time zone, you have to take into account what your body thinks. What, excuse me, you have to take into account where your body thinks you are. And so if you're looking at the Italian sunrise, having just flown from New York to Italy, and you didn't prepare for that trip by waking up a little bit earlier in anticipation.

• 1:47:34Speaker 07

  Multiple days.

• 1:47:35Andrew D. Huberman?

  And you view light at two a, excuse me, at at six or seven a.m. Italian time, beautiful Italian sunrise. You are going to delay your clock. You're going to basically throw yourself back to California, but you are in Italy. You're going to throw your biology back to California, and you are going to be up in the middle of the Italian night. And you're going to be miserable. I'll tell a brief anecdote because I called Sam. In desperation, a few years ago, I traveled to Abu Dhabi, NYU Abu Dhabi, to give a seminar. Twelve hours out of phase, it's a twelve hour flip. And I thought I could just muscle it. I thought I'll get up, just view sunlight when the sun comes up. And I fell apart mentally and physically. And Samer came to my rescue. I called him, I said, I don't know what to do.

• 1:48:19Andrew D. Huberman?

  And he said, go to the gym, at the local dawn, workout, eat, and then view sunlight, starting the next day. And that basically got me on the schedule. So I used food and exercise to adjust myself because my light viewing activity was just completely out of whack.

• 1:48:38Speaker 07

  Yeah, I mean, and we talked about other details. So you have to calculate it, but you're absolutely right. I mean, it's, it's very important to avoid getting the wrong light information when you're trying to adjust your body. Because otherwise, it shifts you to the other, to the other cycle. Absolutely right.

• 1:48:56Andrew D. Huberman?

  Well, you are one of these people that has such vigor. It's one of these things where, having known you all these years, you have a tremendous capacity for work and for soccer and for arguing, respectful arguing and, you know, sometimes, you know.

• 1:49:11Speaker 07

  It's getting worse with age.

• 1:49:12Andrew D. Huberman?

  Yeah, well, we could talk about that offline. But I think a lot of your vigor and a lot of your ability to work hard and focus and really do so many things at an impressive level is because you think about these issues and you, you think about when you're going to be optimal for focus, when you're going to be optimal for exercise, when, and the when is the key. It's, and I think a lot of people live in the landscape of feeling like there's something broken inside them because they can't focus or they can't do it.

• 1:49:40Speaker 07

  Subconscious, right? Remember, it's all subconscious, these effects. And you're absolutely right. Now, honestly, joking aside about age, I really agree with you that. I think part of the reason I'm continuing to be able to do this, that I really think about it and I make sure that I keep everything aligned. And, and that actually helps me a lot. Like, I don't suffer in sleep, I don't suffer in waking up. I never use a timer to wake up. I mean, people say, aren't you scared? Like, you have to give a lecture at eight or seven thirty. I was like, there is no way I'm gonna go beyond that. It just, even if I try, I can't sleep beyond six AM in my regular times. It's just, it's not gonna happen. By four thirty, my eyes are wide awake and I'm in bed.

• 1:50:23Speaker 07

  It's just, system is so aligned, it works.

• 1:50:28Andrew D. Huberman?

  A lot of times, people will say, how come I go to sleep, I fall asleep, fine, but then I wake up at three or four in the morning and can't fall back asleep? Is it possible that those people were supposed to go to bed at 8:00 PM?

• 1:50:39Speaker 07

  It's possible. I mean, it is possible. It is also possible that sometimes people will wake up and go back to sleep. But, but yeah, I mean, it is possible. Or it's possible that their clock is completely misaligned, that they are getting maybe nap time at night when they are supposed, and then they possibly feel so sleepy in the day. So they're, all these are possible combinations.

• 1:50:59Andrew D. Huberman?

  That's an interesting idea I hadn't considered. So that what they think is their sleep, their body is so out of whack with the light-dark cycle that it's actually a nap.

• 1:51:08Speaker 07

  Or, or the weaker part of the sleep. I mean, you see this in, in, when you travel to different time zones before you adjust. You go to sleep really well, but two hours later, you're fully up. Two hours. If you were so tired and this is your regular sleep, there's no way you're gonna wake up in two hours. So then you feel very sleepy later in the day or something like that. So it depends of how your whole system is aligned to the environment.

• 1:51:34Andrew D. Huberman?

  That's a very interesting idea. I, I, I think that's gonna resonate with a lot of people. I wake up every morning around, um, three or four. I generally use the bathroom and then I fall back asleep very, very deeply. Doesn't seem to disrupt my daytime wakefulness. Um, and I think a lot of people obsess over that, that waking up and worry there's something wrong. Provided they can go back to sleep, it's okay.

• 1:51:56Speaker 07

  If you can go use the bathroom, go back to sleep, that should not be a problem. Maybe some people, when they go to use the bathroom, they use very bright light and then they get an alerting signal. So if, if you, maybe that's, it could be as simple as that, that affects you. Maybe when you wake up, you put tons of light or you start reading your iPad. So there's all these combinations that we still don't know about that could be affecting their sleep-wake rhythms and their sleep maintenance.

• 1:52:23Andrew D. Huberman?

  Do you use melatonin? Uh, do you take melatonin?

• 1:52:26Speaker 07

  I don't need it, to be honest. In my case, there is no reason to use it because I could guarantee you that by maybe eight o'clock, my melatonin has already started to go up. And by the time I sleep, my melatonin is very high because I don't use a lot of lights after sunset.

• 1:52:42Andrew D. Huberman?

  And light inhibits melatonin.

• 1:52:43Speaker 07

  And light really blocks melatonin level.

• 1:52:46Andrew D. Huberman?

  You hear this myth that the pineal gland calcifies as we get older. Is that, do you know anything about that?

• 1:52:52Speaker 07

  I mean, I've heard about that, but I don't know what does. I mean, there is not very clear evidence that affects the sleep. I don't know much about it, to be honest.

• 1:53:00Andrew D. Huberman?

  Yeah, the evidence that I've seen is that, yes, there's some calcification around the pineal just because of where it sits in the, in the brain. It's close to some bony, bony structures, but I don't think there's any evidence that it has negative effects.

• 1:53:14Speaker 07

  I mean, if, if you still have, you could measure melatonin and that should tell you if it has. It's such an easy thing to do.

• 1:53:21Andrew D. Huberman?

  I think this is more of a, of an internet wellness thing that, that got outside the cage.

• 1:53:27Speaker 07

  You're absolutely right.

• 1:53:28Andrew D. Huberman?

  Yeah, it sounds terrible, calcification of the thing, right?

• 1:53:33Speaker 07

  The heart thing, right?

• 1:53:34Andrew D. Huberman?

  Yeah, exactly. Let's talk about seasonality a little bit. I learned, and I don't know if this is still true, but that most suicides occur in April, in the spring. I think there's a poem that says, April is the cruelest month. I think it is the poem begins. Are there data that suicides are more frequent at particular times of year? And if so, is the spring that time of year?

• 1:54:03Speaker 07

  Yeah, I mean, a lot of people talk about this and, and one of the hypothesis that is that the winter month that are very bad for mood make people not wanting to do anything. And they have, they get into such deep level of depression that when the sun comes up, they get actually the energy to act on their depression, which sounds really terrible. And it is terrible.

• 1:54:25Andrew D. Huberman?

  It's terrible.

• 1:54:26Speaker 07

  So that's, so that's the idea that the lack of light throughout the winter caused them to go into such depression that they don't feel like doing anything. And when the light comes in with rigor in the spring, it gives them that, after all the depression they suffered, it gives them that push to, to take that sad. Final, you know, act, I guess.

• 1:54:47Andrew D. Huberman?

  What other seasonal effects have been demonstrated in humans?

• 1:54:50Speaker 07

  Yeah, I mean, I think in humans, it's not very clear because we don't think about seasonality. But if you start thinking about us, I think we go through major seasonal changes. I really do. I think our eating pattern change across the year. I could tell you that me thinking about this, there is a clear changes that happens to me across the year. But for animals, this is really essential because for animals, they have to time their mating behavior was when they deliver their their progeny in the most abundant amount of food. And artificial light is causing major disruption because if you change the way these animals are receiving the light information,

• 1:55:32Speaker 07

  they either start mating much earlier or much later and their numbers dwindle and they get into the dangers of really completely getting eliminated or extinct.

• 1:55:42Andrew D. Huberman?

  Well, human birth rates are definitely going down. I mean, in the US, in the US in particular.

• 1:55:47Speaker 07

  Yeah, not others.

• 1:55:48Andrew D. Huberman?

  Not others, right.

• 1:55:51Andrew D. Huberman?

  But are there other effects of seasonality on humans that we are aware of?

• 1:55:55Speaker 07

  I honestly, like you could see it, honestly, you could see it perfectly, I think, in in Scandinavia. I mean, you could talk to people in who live in.

• 1:56:04Andrew D. Huberman?

  Sure, they get seasonal depression.

• 1:56:06Speaker 07

  What seasonal depression is one, but actually, when you start asking them questions, they tell you like in the winter, they barely could wake up. They barely have the energy before even depression, even people who don't get seasonal depression. They'll tell you our energy level is lower, our ability to go to work is is not the same. And in the summer, most people actually sleep very little. They tell you we we really can, we feel like we're manic, we have all this energy. And not in a negative way, in a funny way, right? I mean, but if you want to sleep, we have to put these curtain. I think in these situations, you could really appreciate the seasonality of the humans. I think we kind of destroyed our seasonality because we don't get exposed.

• 1:56:51Speaker 07

  To that much natural light, we have all this artificial light. But I think honestly, one of the thing that is gonna happen if they follow your recommendations about giving light at the same time, giving food, giving exercise.

• 1:57:04Andrew D. Huberman?

  Wait, let's be clear, those are your recommendations. No, I'm just, I'm just fair attribution.

• 1:57:09Speaker 07

  What I'm saying is that this is gonna cause them to also experience some changes across the season because now they're gonna see the sun differently. If you're gonna go out in the morning in the summer, you're gonna get a much brighter. That's why I don't like the change in time. I know people think, oh, because you're biased, you, because I think.

• 1:57:28Andrew D. Huberman?

  Wait, wait, wait, sorry, the change in time, are you talking about daylight savings?

• 1:57:31Speaker 07

  Daylight saving, it's such a bad idea because it disrupts that rhythm that you're having. Because I think your body, if you keep that rhythm, you will see the whole seasonality. And I look at it from a different aspect than other people. It really, and people say I'm biased because I'm a morning person, and it may be true. But there's situation.

• 1:57:52Andrew D. Huberman?

  Secret conspiracy about morning people.

• 1:57:54Speaker 07

  Yeah, but there is, if you think about it, Andrew, there is a situation where you're getting light perfectly well, and then all of a sudden they delayed by one hour because, and then even though it's the summer, your body now, if you're still not adjusting, think, oh, wait, what happened, what kind of happened?

• 1:58:11Andrew D. Huberman?

  Well, I'm glad you're bringing this up because I always thought, you know, what's the big deal, one hour, right, one hour shift, you know, spring forward, fall back.

• 1:58:19Speaker 07

  It's so hard to adjust to one hour.

• 1:58:21Andrew D. Huberman?

  But the, but this goes back to the beginning of our discussion, it's not just one hour.

• 1:58:26Speaker 07

  Right.

• 1:58:26Andrew D. Huberman?

  Because it's one hour across that one day, but there's this cumulative effect on the clock and these three elements of your tripartite model, right? The homeostatic sleep and the light direct effects on mood.

• 1:58:38Speaker 07

  And when it's so close, it's sometimes hard to figure out how to adjust it perfectly because, you know, we're already sleep deprived in our society. And then you shift it by, you know, so it, it just, it all accumulates and it has no benefit.

• 1:58:53Andrew D. Huberman?

  Well, you work at a major government organization, National Institute of Mental Health, why don't we campaign for?

• 1:58:59Speaker 07

  Honestly, I have no idea, I mean, it makes no.

• 1:59:01Andrew D. Huberman?

  No, I'm saying, why don't we go campaign?

• 1:59:03Speaker 07

  Yeah, I would love to, I mean, it makes no sense to have the summer light goes up at nine P M, the light goes down where I live in Baltimore at nine P M, and then all of a sudden. When you really want to see the light longer in the day, you now shift the other way. And now it goes oriflal at 6 P M. Why do you do these drastic changes? Well, let it blend across the whole season. You know, yes, later, earlier at night, but it's at least consistent. It goes in a very consistent manner. I just don't understand why they do this. It makes no sense.

• 1:59:36Andrew D. Huberman?

  Well, I think that the reason they do it is because they don't understand the biology. Because one hour seems trivial unless you understand the repercussions of that one hour shift. Because what's also clear now, based on what you're saying, is that that one hour shift is taking you out of alignment with the natural light dark cycle in exactly the wrong direction.

• 1:59:57Speaker 07

  It's pushing people to get even later. In the summer, when light is gonna push you later anyway. It doesn't make sense. You put it beautifully. I just rambled and this is.

• 2:00:08Andrew D. Huberman?

  No, no, you made it. You made it clear.

• 2:00:09Speaker 07

  I mean, it's like literally it made you. It made people who are having problem, having an advanced sleep rhythm because they are delayed. Now you give them this hour to make them even more delayed. You push them even later in the day night cycle. It just doesn't make sense at all.

• 2:00:27Andrew D. Huberman?

  I think 2022 should be the year that we abolish daylight savings.

• 2:00:32Speaker 07

  The day for me, honestly.

• 2:00:33Andrew D. Huberman?

  Well, essentially, well, also, if it has a positive effect on the, what is essentially an epidemic of mental health issues and other issues related to improper interactions with light. That, I think, is a well worthwhile cause. And we can explore. So for once, we're gonna fight with some, with another group, a common battle as opposed to with one another.

• 2:00:57Speaker 07

  I mean, the circadian people, honestly, if you give them credit, have been trying for years to abolish daylight saving.

• 2:01:03Andrew D. Huberman?

  Yeah, the problem is they all go to sleep at 9 P M. and wake up at 4 A M. So we never see them.

• 2:01:07Speaker 07

  That's right.

• 2:01:08Andrew D. Huberman?

  Uh, no, the circadian community has done an amazing job of. Figuring out what we need.

• 2:01:15Speaker 07

  Right.

• 2:01:15Andrew D. Huberman?

  And then the challenge, of course, is making sure that people get what they need.

• 2:01:20Speaker 07

  Right.

• 2:01:20Andrew D. Huberman?

  And making sure that at a societal level, we're not vaulting ourselves into the wrong.

• 2:01:25Speaker 07

  And the biggest problem is that the late waking people, they think that really, and I'm gonna try to put it in a better way now. They think, oh, because you're a morning person, you wanna see the sun early, so you want me to suffer it dropping late. But that's not the case, because what happens is when they shift it back after the daylight saving, now they're gonna make you suffer really badly, because now it's gonna be earlier.

• 2:01:52Andrew D. Huberman?

  Right, in the fall.

• 2:01:53Speaker 07

  In the fall, when there's not enough light. If they keep it the same way, so try to convince them that actually this at the end causes more trouble when you need the light for your late schedule in the fall, when they shift it back. Then they say, keep it daylight saving all the time, and that has been proven that is very bad. Like, people have done studies that literally two areas close to each other's and areas that were the whole year on daylight saving has much more problems, even in cancer rates and depression, so you don't wanna do that. So that's what trying to convince people that you need to prevent that switch and you don't need daylight saving at all. That's where the problem happens.

• 2:02:38Andrew D. Huberman?

  Interesting. I had not thought about that, but yes, you late risers, the in the fall, when they, when the fall back, as they say, spring forward, fall back, you dial back the clock, it's really compounding the problem that already exists.

• 2:02:52Speaker 07

  And it's really nice if you think, if you keep it consistent. In the spring, you get the, you know, when you you get the equinox and then the days start going up, and then even in the summer start going down, then the fall, you get the other equinox and go back. So it's very symmetrical, right? It goes into short day, longer, long, long, then short day again. But now you're getting these bumps in both sides of the spring and fall. Why would you do that? Something that is beautifully symmetrical, beautifully smooth, you're putting bumps into it.

• 2:03:23Andrew D. Huberman?

  Well, and we, not just beautiful because it's there, but it but evolved. I mean, essentially, this is the system we evolved in for hundreds of thousands of years.

• 2:03:31Speaker 07

  Even apart from the exact equator, every part of the earth have seasonality.

• 2:03:38Andrew D. Huberman?

  I want to briefly touch on something which is individual and genetic variation in sensitivity to light.

• 2:03:44Speaker 07

  Yeah.

• 2:03:44Andrew D. Huberman?

  So not chronotype, but

• 2:03:48Andrew D. Huberman?

  first of all, a very basic question. Do people with light eyes, light colored eyes, are they more sensitive to light than people with darker, pigmented eyes?

• 2:03:59Speaker 07

  I mean, honestly, it makes sense there will be more because if you think of my dark pupil, it's blocking more light. So if you have light pupil, yes, for vision, it may not be very obvious, but for something that is measuring the amount of light, you're getting more light than me. So you probably need less light to be effective as somebody who's darker. And that maybe could explain why sometimes lighter people say, I don't want to go into very bright conditions because it's really bright.

• 2:04:28Andrew D. Huberman?

  Yeah, I can't, I can't even be at a cafe with one of these reflective tables, like a metal table, unless I have very dark sunglasses on.

• 2:04:35Speaker 07

  Exactly.

• 2:04:36Andrew D. Huberman?

  It's so bright, it's painful for me. Whereas some people like you, we've sat outside and had meals and you're like, fine. I assumed it was kind of Jordanian toughness.

• 2:04:43Speaker 07

  No, no, no, it's really the pupil blocks more light. So I think it is possible that it's as simple as the pupil blocking more light can have sensitivity. But your question is also goes deeper. Are there more sensitivity differences? And my understanding would be, I would think that it may be, it depends on how effective your cells are in responding to light, how healthy your IPRGCs are. So I would, but there's not many studies to show that. What is really clear that is happening is that patients with bipolar, they seem to have different sensitivities to light. So it seems that at least people who have psychological changes, they may have differences to the sensitivity of light. So.

• 2:05:29Andrew D. Huberman?

  Where are those differences in a particular direction?

• 2:05:33Speaker 07

  I don't remember the exact.

• 2:05:34Andrew D. Huberman?

  We'll have to, we can look it up.

• 2:05:35Speaker 07

  Yeah.

• 2:05:35Andrew D. Huberman?

  Yeah.

• 2:05:36Speaker 07

  Yeah.

• 2:05:37Andrew D. Huberman?

  Yeah, I, you know, and people have heard me say this ad nauseam to the point where they actually roll their eyes. But you know, these are the only two pieces of brain, you know, I'm pointing to my eyes, folks, that are outside the cranial vault. They are two pieces of brain that it basically inform the brain about whether or not to be alert or asleep.

• 2:05:53Speaker 07

  Absolutely.

• 2:05:54Andrew D. Huberman?

  But you can imagine that those two little pieces of brain that we call eyes would have genetic variations. Of course, eye color is genetically modula, is that determined? That there would be genetic variations based on whether or not your ancestry evolved near the equator or further from the equator. Right? I mean, you see more blue eyes in Scandinavia than you do.

• 2:06:14Speaker 07

  Absolutely. I mean, it's the lack of light that said you need more, less inhibition because there's not enough light. Right? So that's the idea of the change in color.

• 2:06:24Speaker 07

  So, yeah, I totally agree with you. I mean, I think this is an area that will be studied later and will be empirically determined. The problem we have in this field right now, which I think is the biggest problem, is we don't have a way to measure the IP RGC sensitivities in humans. So we still, like, it's easy to measure your rod corne function. If you go to an optometrist, they measure all the details, right? Contrast detection.

• 2:06:50Andrew D. Huberman?

  You look at the chart, you look at the Snellen chart, you look at the letters of the DMV.

• 2:06:54Speaker 07

  Yeah, but for the non subconscious, we still don't have a good measuring systems to figure out what is Andrews sensitivity, what is Samer sensitivity, what is this person's sensitivity? And I think we're starting to work on something like that to hopefully develop these techniques. But till we develop them, it's going to be very hard to figure out if there is a sensitivity difference. How do they relate on men and women, you know, dark and light and all that, you know, normal versus psychologically on effect and stuff like that.

• 2:07:27Andrew D. Huberman?

  Fascinating. And every time. You talk, I learn so much. It's like a, in the best way, the best sense of the term. It's a waterfall of knowledge. As a final question, I have a question about sensitivity of a whole other kind. And that's the sensitivity to spicy food. Now, the reason I'm asking this question, what seemingly out of the blue, is that I made the mistake once of having Samer cook for me. And I said, "Not too spicy." And he said, "Okay, not too spicy." Yeah, she said, "Okay, not too spicy." And it almost killed me. Like, it was like two or three days.

• 2:08:11Andrew D. Huberman?

  So you know a lot about biology outside the visual system, light, et cetera. You've been around a while. Are there known genetic or inherited of any kind sensitivities to spicy food? To things like red peppers and capsaicin? Because what you call mild, my friend, almost put me into the hospital.

• 2:08:33Speaker 07

  I think this is similar to you swimming in the ocean and I need to get developed the

• 2:08:37Andrew D. Huberman?

  Okay, true, true. I like cold water swims and Samer's not a fan. But that's gonna change. It's adaptable. That's gonna change.

• 2:08:44Speaker 07

  That's my belief. Before I met Raji, I was like you. And once I started eating a lot of spicy food, I lost touch of how spicy my food is. So I nearly killed you, Andra, and I apologize for that.

• 2:08:56Andrew D. Huberman?

  I forgive you. So basically, what you're saying is that marriage toughened you up?

• 2:08:59Speaker 07

  Toughened me up, exactly.

• 2:09:01Andrew D. Huberman?

  Maybe that's, maybe that's the solution.

• 2:09:02Speaker 07

  That's what you need, yeah.

• 2:09:04Andrew D. Huberman?

  Samer, this has been an amazing march through the importance of light, not just for regulating sleep and wakefulness, but also for food timing, the interactions with mood, the interactions with exercise. I'm certain that people are going to start thinking about how to change their relationship with light as a way to anchor everything that they do and that's important to their health. And I just, on behalf of all of them, and just directly from me as your friend and as a colleague for many years now, I just want to say thank you for the incredible work you're doing and for sharing it with us.

• 2:09:40Speaker 07

  Thank you so much. And actually, now thinking about all of this, and you said I should write a book, I should write a book and call it "The Tripartite Model." I think that would put all these components together would be very interesting to do at some point.

• 2:09:54Andrew D. Huberman?

  You should write a book. You should write. They'll probably try and change the title to like Food, Mood and You, you know, or something because, but you can put in little print on the tripart model or whatever. But regardless of what it's called, I, you absolutely should write a book. And, and so if you'd like Samer to write a book, or if you'd like to learn more about him, let's talk a little bit about where people can find you. Your laboratory is at the National Institutes of Mental Health. He is head of the chronobiology unit, all these things that I've mentioned earlier. But you are active on Twitter and Instagram.

• 2:10:26Speaker 07

  Right.

• 2:10:26Andrew D. Huberman?

  So what is your Twitter handle?

• 2:10:28Speaker 07

  It's at Samer Hattar.

• 2:10:31Andrew D. Huberman?

  And we will provide a link for that in the, in the show notes.

• 2:10:33Speaker 07

  Sorry. Yes, at the Twitter at Samer Hattar. And I think the same for Instagram.

• 2:10:38Andrew D. Huberman?

  Yeah, actually. And Samer has been coaxed onto Instagram. So he does post from time to time, mostly pictures of food that is incredibly spicy, but also information about chronobiology. He comes on for an Instagram Live every once in a while with me. And so definitely give him a follow there and on Twitter. And, and I'm sure that he'll be happy to answer questions and entertain any and all discussions about chronobiology.

• 2:11:06Speaker 07

  Absolutely. Yep. And light. Yeah.

• 2:11:10Andrew D. Huberman?

  Great. Thank you, Samer.

• 2:11:11Speaker 07

  Awesome. Thank you, Andrew.

• 2:11:13Andrew D. Huberman?

  Thank you for joining me for my conversation with Dr. Samer Hattar. I hope you found it as interesting and informative as I did. If you're enjoying this podcast and we're learning from it, please subscribe to our YouTube channel. In addition, please leave us comments and feedback in the comment section on YouTube. A great thing to do there would be to make suggestions about future topics you'd like us to cover or future guests you'd like me to host on the Huberman Lab podcast. In addition, please subscribe to our podcast on Apple and Spotify. And on Apple, you can leave us up to a five star review. Please also check out the sponsors that we mentioned at the beginning of the podcast. That's a terrific way to support us.

• 2:11:51Speaker 01

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  On October 2nd.

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  I'm not the first man.

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  Digger. See the trailer online. Only in theaters October 2nd. Rated R. Under 17. Not a minute without parent.

• 2:12:21Andrew D. Huberman?

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