The Paradox of Sleep with Matthew Walker

What happens when we go to sleep? Neil deGrasse Tyson and co-hosts Chuck Nice and Gary O’Reilly break down the mystery of why we sleep, time dilation in dreams, circadian rhythms, and sleeping in space with neuroscientist Matt Walker.

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

• 0:00Neil deGrasse Tyson?

  Coming up on StarTalk's special edition, it's all about sleep. And we learned what it is, why we need it, how it impacts our perception of time, and how it is that we actually go crazy when our head hits the pillow as we drift off in slumber. Coming up on StarTalk.

• 0:21Neil deGrasse Tyson?

  Welcome to StarTalk, your place in the universe where science and pop culture collide. StarTalk begins right now.

• 0:35Neil deGrasse Tyson?

  This is StarTalk. Neil deGrasse Tyson here, your personal astrophysicist. I got Chuck Nice, my co-host. Chuck? Hey, what's up, Neil? All right, Gary O'Reilly.

• 0:45Gary O'Reilly?

  Hi, Neil.

• 0:46Neil deGrasse Tyson?

  All right, and this is a StarTalk special edition, all about sleep. Gary, what have you put together today?

• 0:54Gary O'Reilly?

  Well, sleep, Neil. We all do it. Some better than others, but why? And why have humans not evolved to do without it?

• 1:04Neil deGrasse Tyson?

  I've been asking that my whole life.

• 1:05Gary O'Reilly?

  Here we go.

• 1:05Neil deGrasse Tyson?

  What a waste of time this is. What a waste of time.

• 1:08Gary O'Reilly?

  Now we're gonna get somewhere, right? What are circadian rhythms and what are chronotypes? What actually defines a good night's sleep? Um, what's it gonna be like sleeping in space? Uh, there is so much to understand, so let's go grab ourself an expert. Neil, if you would like to introduce our guest, and just because you sleep at night doesn't make you an expert, all right? We need a real expert. We need a real expert.

• 1:34Neil deGrasse Tyson?

  We got Dr. Matt Walker. Matt, welcome to StarTalk.

• 1:37Speaker 02

  Oh, it's a delight and a privilege. And I have to say, I'm a little intimidated by the intellectual horsepower that's on display across all three of you. But I am, um, it is, it is such a privilege.

• 1:49Gary O'Reilly?

  You mean me? You mean me, Matt?

• 1:51Speaker 02

  Well, let me be agnostic in terms of where I'm.

• 1:54Neil deGrasse Tyson?

  At University of California, Berkeley.

• 1:56Speaker 02

  I'm applying it. Uh, oh, no, don't be fooled by that, all the accent. Um, yeah, my, um, I think someone last week suggested that I'm, if I were any more stupid, you'd have to water me twice a week, so just be warned.

• 2:09Gary O'Reilly?

  Wow.

• 2:10Neil deGrasse Tyson?

  I love that reference. That's, that's hilarious. That's great. That's very funny. So you're a professor of neuroscience and psychology at University of California, Berkeley. That presumably means you have an official appointment in two departments. Is that correct?

• 2:23Speaker 02

  I do, indeed.

• 2:24Neil deGrasse Tyson?

  And you're the founder and director of the Center for Human Sleep Science at UC Berkeley, with center spelt C E N T R E. Is that correct in my notes here?

• 2:35Speaker 02

  That is very correct.

• 2:37Neil deGrasse Tyson?

  How evil of you.

• 2:38Speaker 02

  British nature, I know.

• 2:39Chuck Nice?

  Clearly, clearly, somebody's, somebody's not getting enough sleep to spell correctly.

• 2:43Speaker 02

  Oh, there are going to be so many instances of my faux pas that you'll be able to point out and say, this guy must be on for three hours of sleep based on his idiocy. So inbound.

• 2:56Neil deGrasse Tyson?

  And author of the bestseller, Why We Sleep: Unlocking the Powers of Sleep Plus Dream. And you're, you're a TED Talker. Why wouldn't you be after all that? And you are the host of the boringly titled, The Matt Walker Podcast. What's up with that?

• 3:14Speaker 02

  I know. You know, the, the team around me, we had one of these retreats, three or four days bashing around titles. And I think the, the innovation there was stunning. The Matt Walker Podcast. You can see that we're a creative bunch in this domain. So deeply, deeply embarrassing.

• 3:36Neil deGrasse Tyson?

  At the end, we're just going to agree that you need more sleep. Okay, that's what's going to happen here.

• 3:40Speaker 02

  Yeah.

• 3:41Neil deGrasse Tyson?

  I want to know, why do we need sleep at all? I see that as a shortcoming of the human brain. If aliens came and they just watched us just lay down and be semi-comatose for one third of Earth's rotation, they'll wonder, what's wrong with these people?

• 3:57Speaker 02

  Isn't it stunning? And when you think about it from an evolutionary perspective, it makes no sense. Because first, we're not finding food. We're not finding a mate. We're not reproducing. We're not caring for our young. And worse still, we're vulnerable to predation. So on any one of those five grounds, but especially all of them as a collective, sleep should have been strongly selected against in the course of evolution. But the fact that in every species that we've studied carefully, even evolutionary ancient, old species, every species seems to sleep or have something like sleep.

• 4:39Speaker 02

  What that means is that sleep evolved with life itself on this planet and then has fought its way heroically through every step along the evolutionary path, which must mean that sleep is absolutely vital. And in fact, it's once been said, to your point, Neil, that if sleep doesn't serve a critical set of necessary functions, it's the biggest mistake the evolutionary process has ever made.

• 5:09Chuck Nice?

  I'm going with the latter.

• 5:12Speaker 02

  Man after my own heart. No, no, no, just let's get the honesty out on the table.

• 5:17Neil deGrasse Tyson?

  Put it out up there.

• 5:18Speaker 02

  Yeah, please, please. But we now have a huge collection of science that suggests that why Mother Nature did not make a spectacular faux pas in creating this thing called sleep.

• 5:30Neil deGrasse Tyson?

  So do worms sleep? When you say animals, are you not just talking about just vertebrates or mammals? You mean all animals?

• 5:36Speaker 02

  Yeah, so even earthworms, which are so old from an evolutionary perspective, they have states of activity and inactivity. And if I were to show you on a, on a video, it's really quite telling that they seem to have, it may not be sleep, we call it lethargicus in these species. It's the kind of fancy earthworm way of saying, you kind of, you kind of look like you're asleep, but we can't ask you the question. But yeah, but yes.

• 6:05Chuck Nice?

  It could, it could be, it could be they're just lazy, you know?

• 6:10Speaker 02

  That's right. They are lazy at very predictable times across the 24 hour period. But despite that, you know, when they put their feet up, who knows what they're watching? Maybe it's earthworm Netflix. I don't know, but they do it in a very stable predictive way.

• 6:25Neil deGrasse Tyson?

  So do, do, I hate using this term, but you'll know exactly what I mean. Do higher level animals require more sleep than lower level animals?

• 6:35Speaker 02

  It's a very interesting question, which is can we understand the functions of sleep across phylogeny, across different species? And it's been fiendishly difficult. Because there are some species, such as the little brown bat, it's the rock star of sleep, sort of Keith Richard, you know, that little brown bat can sleep up to nineteen hours per day, whereas if you look.

• 7:01Chuck Nice?

  Really, you talk to my cat.

• 7:03Gary O'Reilly?

  Yeah.

• 7:04Speaker 02

  It's trying to challenge that.

• 7:06Gary O'Reilly?

  We've got cats that can do that.

• 7:07Chuck Nice?

  That bat has nothing on my cat, man, I'm sorry.

• 7:12Gary O'Reilly?

  All animals that end in A T can do at least nineteen hours a day.

• 7:16Speaker 02

  Yeah, it seems to be, but but then if you look at, you know, elephants, for example, they sleep maybe just two to three hours. And you think, well, is there a correlation between size then? Absolutely not, there is no correlation. Is it about the size of the brain? Nothing to do with the size of the brain. Is it about prey versus predator and your status on that hierarchy? Not at all. Is it about the complexity of your nervous system? A little bit, but not much. Omnivore, herbivore, carnivore, does that predict? No, it doesn't. If you are temperature regulated, thermoregulatory, or you're not, nothing.

• 7:57Neil deGrasse Tyson?

  Warm blooded or cold blooded?

• 7:58Speaker 02

  Warm blooded, cold blooded. But we're starting to understand that it's actually a complex set of all of these different things. Metabolic rate does seem to be predictive, and such that if you have a higher metabolic rate, you your idea would be, well, then you need to sleep more to sort of restore that. It's the opposite. Higher metabolic rate, you need to stay awake for longer so you can get in enough calories to support your higher metabolic rate. And so it's a very complex question, but to your point, no, there is no simple correlation that explains the vast variance of sleep across species.

• 8:37Neil deGrasse Tyson?

  One question before I hand over to my co-host here. So we've heard things about sleep rhythms and maybe leading the pack, there's circadian rhythms. Could you just shed some light on that? I think Chuck had a question about that, too.

• 8:55Chuck Nice?

  Yeah, well, no, I just, I was wondering if like the earthworms had a circadian rhythm, because that's one, one of the defining attributes of sleep is the fact that you actually do it at kind of the same time in the cycle of the day.

• 9:12Speaker 02

  You're absolutely right. So that's one of the, so let me start with what circadian rhythms are and sort of break the term down. Circa sort of around approximately and rhythm, we all know what that term is. So in other words.

• 9:27Chuck Nice?

  Circa, that's the same Latin word when circa eighteen thirty-two.

• 9:32Speaker 02

  Yeah.

• 9:32Chuck Nice?

  Or something. Okay, cool.

• 9:33Speaker 02

  Exactly. And then you've got dian from the Latin derivative of day. So in other words, it's a, it's a rhythm of around or approximately one day. Why is it not precisely one day? Well, when we've done studies where we take human beings, there's a famous study with a professor Nathaniel Kleeman and, and they went off down to Mammoth Cave, deepest cave in America.

• 10:00Chuck Nice?

  I remember this study.

• 10:01Speaker 02

  Yeah. And where there is no light.

• 10:03Chuck Nice?

  And they just lived whatever day they wanted, right?

• 10:05Speaker 02

  And they just lived and they wanted to see what happens to their sleep-wake rhythms. Do they just abandon all timing? And the answer was no. They stuck to a very close timing. But it was close to 24 hours, but it wasn't precisely 24 hours, when they cut themselves off from the outside world, specifically the most predictable thing on this planet, which is that since the dawn of time, unless you want to correct me, the sun has always risen and the sun has always set. And it's set in that 24-hour rhythmic nature. And when they decoupled themselves from that rhythmic signal, the body still kept its 24-hour rhythm

• 10:47Speaker 02

  almost. It was just a little bit laggy and it ran about 24 hours and about 30 minutes. And now we've figured this all out in big studies and it's about 24 hours and 12 minutes that we run a little bit late if we're disconnected from the outside world.

• 11:05Neil deGrasse Tyson?

  That's why I always want to sleep an extra thirty minutes after the alarm clock.

• 11:09Speaker 02

  Please do that. Please do that. Or better still, remove the alarm clock and just add an extra half hour. But you will just, yeah, but if I were to disconnect you like they did with In Mammouth Cape, you'd just drift forward in time. You keep adding on about fifty minutes. So that's, so it's a, that's why we define it as about twenty-four hours. But beautifully, when we're living in the real world, we have cues of that twenty-four hour period, like light, but also feeding at certain times. Those cues, which are what we call zeitgäbe, from the German term "time giver", act like little fingers to pop out the dial on your wristwatch

• 11:53Speaker 02

  and reset it to twenty-four hours each day, so you don't drift. But coming back to Chuck's question, that's one of the ways that we define sleep in species where it's hard to sort of place electrodes in or place electrodes on their heads. So we can look to see, do they do that activity and inactivity state in a twenty-four hour predictable rhythm? Yes. Also, another one is, is it reversible? Because that's what differentiates, or it's one of the things that differentiates sleep from death, which is that when an organism goes into this state of inactivity. Yeah, yeah, I was gonna say, it's not the only one, don't worry. But if you prod the earthworms, then they seem to come back to life as if they were absent this waking state.

• 12:38Gary O'Reilly?

  So Matt, when you've got circadian rhythms and it's trapped into a twenty-four hour-ish cycle by obviously clinical experiment, what happens if you're an early bird or a night owl? And you call those chronotones, correct?

• 12:53Neil deGrasse Tyson?

  You know, there are early people and there are morning people and there are night people.

• 12:57Gary O'Reilly?

  So, so how are we, I mean, is that disruptive? Or is that, is that just, you know, some people have software uploaded that does that? Other people have this?

• 13:07Chuck Nice?

  There are party people and then there is everybody else.

• 13:12Neil deGrasse Tyson?

  And plus Gary, the term for your brain is not software, it's wetware. We have different wetware.

• 13:17Gary O'Reilly?

  Okay, sounds like I'm scuba diving, but I'll go with that.

• 13:22Speaker 02

  Scuba diving with Matt Walker on Star Trek.

• 13:25Neil deGrasse Tyson?

  Hardware, software, wetware.

• 13:28Speaker 02

  So isn't it, isn't it a strange thing? And we are, we are defined by our chronotype. And our chronotype, by the way, whether you're an evening type, morning type, or somewhere in between, it's about a third, third split across the population. It is not your fault. It is genetically determined largely. And there are at least 22 different genes that we now know will dictate your chronotype destiny. It's gifted to you at birth. You can't really change it very much, unfortunately. But how does this fit in with that strange sort of circadian rhythm? I just told you, everyone has. But these chronotypes, as I said, it's, there are essentially three types and it's genetically determined.

• 14:14Speaker 02

  What's interesting about those is how it changes what I just told you about the 24 hour clock face, the circadian rhythm. I told you that we have a rise where a diurnal species were active during the day and then were asleep at night, active during the day. So how does chronotype fit into your innate circadian rhythm? Chronotype dictates where that sort of sine wave, where that oscillation of rising activity and then the lull of sleep, where that sits on the 24 hour clock face. So we all have a circadian rhythm. But if you are a morning type, your peak activity will arrive earlier on the clock face. Whereas if I'm a neutral, which I am, I'm just going to sit somewhere in the middle.

• 14:59Speaker 02

  And then the, you know, the party people, Chuck not saying anything. Their peak of activity won't start happening or rising until the afternoon. Everyone has a 24 hour rhythm. Where that rhythm sits on the clock face and is positioned is dictated by your chronotype. Does that make any sense?

• 15:20Chuck Nice?

  Yeah, yeah. So the chronotype is like a dial that sets the place where you fall on that wave.

• 15:26Speaker 02

  Beautiful. Yes, exactly that.

• 15:44Neil deGrasse Tyson?

  So man, I get it. You can describe what you already see in us. And that sounds very erudite. But scientifically, what I really want to know is what the hell is going on inside of us while we're asleep?

• 15:58Speaker 02

  And we now know that. And we know it from a broad perspective in terms of whole-brain activity. And we also know it right down inside of a cell itself in terms of the expression of genes and everything in between. I mean, we have, you know, sliced and diced sleep in all sorts of ways. But I'll just give you some highlights. Upstairs in the brain, it is stunning. It is a spectacular display of electrical symphonic ballet. And trust me, if you saw it, you would be stunned. And in fact, we've even extracted these brainwaves from the sleeping brain. And we've converted them into sound files. So that, and you could, it's amazing.

• 16:43Speaker 02

  So what happens is that when we're awake, we have very fast frenetic activity. Your brainwave patterns, or patterns, sorry I should say, are going up and down many, many times per second. Maybe 50, 60 times per second. As you start to fall asleep, those brainwaves start to slow down. And when you go into the deepest stage of what we call non-rapid eye movement sleep. So you have two main types of sleep. Non-REM sleep and REM sleep, non-rapid eye movement sleep, rapid eye movement sleep. And non-REM sleep, you can split it up into light non-REM, deep non-REM. When you go into deep non-REM, something incredible begins.

• 17:27Speaker 02

  All of a sudden, hundreds of thousands of brain cells all decide to synchronize in their firing in unison. So they all fire together, and then they all go silent together. And they all fire together. It's almost like this mantra chant. And it produces these huge, powerful, deep, slow rhythmic brainwaves that have riding on top of them these incredible bursts of electrical activity called sleep spindles. And so this is stunning. And then you go into REM sleep and then the brain becomes once again frenetic. In fact, if all I had was your brainwave activity, Neil, during REM

• 18:08Speaker 02

  sleep, and I was in the other room and you're in my sleep center, I could not tell in the bed, are you awake or are you in REM sleep? In fact, some parts of your brain are up to 30% more active when you are in REM sleep and dreaming, which is stunning. And then downstairs in the body, gosh, as you go into deep sleep, it provides almost the very best form of naturalistic blood pressure medication that you could ever wish for. Your heart rate drops, your blood pressure lowers, your immune system kicks into high gear. Upstairs, coming back to your brain, the, there is a cleansing system that starts to pulse and it flushes

• 18:49Speaker 02

  out all of the toxins. So it's literally a power cleanse for the brain at night. There are so many stunning things. These are just a few that I could regale you with.

• 19:01Gary O'Reilly?

  All right. Well, listen, I gotta go take a nap.

• 19:03Speaker 02

  My work here is done, Chuck.

• 19:06Gary O'Reilly?

  Given that these things are happening, Matt, is the brain able to improve mental health? Is it having an effect on things like dementia?

• 19:15Speaker 02

  It does. It radically alters both what we call your cognitive functions, so learning, memory, and also your emotional and your mental health processes. So in terms of emotional and mental health, we've done a lot of work, and we do a lot of work at my sleep center on this. Firstly, sleep and particularly dream sleep seems to provide a form of almost overnight therapy where it will take difficult, painful experiences and it will essentially act almost like a nocturnal soothing balm and just take the sharp edges off those painful experiences so that you come back the next day and you don't feel as bad, they don't feel as painful anymore.

• 20:01Speaker 02

  And so it's not time that heals all wounds, but it's time during sleep and specifically dream sleep that offers that emotional convalescence, as it were. So that's one of the the mental health benefits. There was a great quote, by the way, Joseph, E. Joseph Cosman, an American entrepreneur, he once said that the best bridge between despair and hope is a good night of sleep. And that's exactly what we've discovered in the laboratory. Your other question, Gary, is very interesting about cognitive function and Alzheimer's disease. What we have discovered is that so there are at

• 20:39Speaker 02

  least two toxic proteins underlying the disorder of Alzheimer. One is amyloid protein, beta amyloid protein, and the other is called tau protein. And what we discovered is that during sleep and particularly deep sleep at night, there is this pulsing sewage system. It's called the glymphatic system. You have one in your body. It's called the lymphatic system in the brain. It's called glymphatic system. And it only kicks into high gear during deep sleep. And it sort of washes out all of the metabolic detritus of the day. Two of the proteins, the toxic proteins that sleep will wash away every night, if

• 21:21Speaker 02

  you are getting enough of it, are these two Alzheimer's proteins, amyloid and tau protein. And that's why we found such strong links between insufficient sleep across the lifespan and your risk for developing Alzheimer's disease. So from that perspective, it's a form of almost, you know, good night sleep cleaning.

• 21:41Chuck Nice?

  So is there any work being done to figure out how you might induce that artificially? Or is the cleaning of this amyloid plaque by your brain not significant enough that it might be able to ward off Alzheimer's altogether? But the mechanism itself, is it something that we could replicate artificially to either aid in that process?

• 22:10Chuck Nice?

  Or just do it.

• 22:12Speaker 02

  Fantastic question. And in fact, it's a question that we have addressed. We started to develop a technology based on something called transcranial direct current stimulation. It sounds like the stuff of science fiction, more your stuff than the mine, but I promise you it's not. You apply electrodes to the head and you insert a small amount of voltage into the brain. And it's so small, you typically don't feel it, but it has a measurable impact. And if you apply that stimulation during sleep, during those big, powerful, deep, slow brainwaves, when we get this cleansing, you can amplify the size of those deep sleep brainwaves. And we can almost, for example, double the benefit that deep sleep brainwaves give to your memory the next day.

• 22:54Neil deGrasse Tyson?

  So that would mean a short, you can, you can hijack a shorter sleep to make you feel like you had a longer sleep.

• 23:01Speaker 02

  Well, that we don't know. It's, we don't know if by improving the, the, the size of these brainwaves, does that reduce your overall sleep need? And if we could, to your point, Neil, it would suggest that we're almost able to, by compressing sleep through increasing quality, it's almost as though I am, you know, I'm, I'm sort of like zip filing sleep. I just compress down your sleep need by improving the quality. And it's a short term. I mean, that would be spectacular. We haven't found evidence for that yet, but we have found the ability to manipulate this brainwave activity. And we've now since split it out into a startup company to, to develop the device.

• 23:44Neil deGrasse Tyson?

  What intrigues me, the way you described the different parts of the sleep cycle, the sleep, the sleep session. I hadn't thought about this before this moment, that if you sleep for less time than the full allocation, or you're on some travel regimen where there's a time zone shift and whatever, you can get some sleep, serving only some parts of that portfolio of need, leaving out other parts of that very portfolio. So are there? Effects, I mean, you mentioned Alzheimer's, but overall, why can't I just sleep a little longer later? I gotta stay up and pull an all-nighter tonight?

• 24:24Speaker 02

  It's a, it is a very interesting question. Can you essentially, you know, catch up on sleep when you've missed it?

• 24:30Neil deGrasse Tyson?

  Catch up, catch up. We say that all the time.

• 24:33Speaker 02

  You know, just, you know, I've just, I've got to, I've got a tough week this, this week, but at the weekend, don't worry, I'm going to catch up. Unfortunately, many of the processes of sleep, not all of them in truth, but many of them, do not work like the bank. So you can't accumulate a debt and then hope to pay it off at some later point in time. Sleep in many ways, and learning and memory is, is a good example, is an all and offing phenomenon, meaning if you don't sleep within the 24 hours after learning those facts, you can lose the chance to consolidate and hit the save button on those memories. So you end up forgetting the information rather than remembering it.

• 25:17Chuck Nice?

  Yeah. I read the abstract on a study that was talking about that. And what they did was they measured the cognitive retention of people who sleep right after learning something as opposed to those who didn't. And oddly enough, if you want to do well on a test, go to bed, study and go to bed.

• 25:38Neil deGrasse Tyson?

  But suppose you go to sleep during the class?

• 25:40Speaker 02

  Well, you know what? The funny thing is, in my course, I teach a large course here of about five or 600 students on campus, the science of sleep. And at the start of the semester, I say, based on what I know regarding the benefits of sleep on learning and memory, it's the greatest form of flattery for me to see people like them not being able to resist the urge to strengthen what I'm telling them by falling asleep in the class. So feel free just to ebb and flow through consciousness throughout my course. I'll take absolutely no offense.

• 26:13Gary O'Reilly?

  Matt, is there a connection between dreams and time? Because we've had this question pop up before on previous episodes, but without a sleep expert.

• 26:23Neil deGrasse Tyson?

  We all saw the Christopher Nolan movie, Inception, right? Which embedded timeframes within dreams.

• 26:30Gary O'Reilly?

  And Matt may have had a part in that. Did you have a part in that?

• 26:32Speaker 02

  I can neither confirm or deny that, but what I'm about to tell you is very

• 26:41Speaker 02

  congruent with the movie. So time is so fascinating when it comes to sleep because it's a total paradox. On the one hand, you lose all sense of time, meaning that if you fall asleep on a plane, you know, let's say you're a transatlantic flight. When you wake up, what's the first thing that you do? Typically, you look at your clock and you say, you know, how long have I been asleep? Why? Weren't you able to track time in your sleep? No. So you've lost your sense of time during sleep at one level. But then the second level is that when we fall asleep and we go into dream sleep, there, something different happens with time.

• 27:26Speaker 02

  And we've got a neural explanation that I'll come on to. But what is different about dream sleep is that you can get what we call time dilation. And this comes on to the movie Inception, where at the first level down, five minutes in the real world is maybe 50 minutes in the first level of the dream. And then maybe it's five years in the second level. And then maybe it's 50 years in the third level. Now, we don't actually have these levels, as it were. We really just go into the dream state. But it is fitting because when you go into dream sleep, and here's a good example, let's say that you have a snooze button. And your arm goes off and your snooze button is for three minutes.

• 28:10Speaker 02

  So you hit it and you go back to sleep and you go back into the dream that you were having. And then the alarm goes off again three minutes later. But you could absolutely tell me, no, that wasn't three minutes. I was dreaming for what felt like 15 minutes. And so time is stretched and dilated, which means that, yes, Inception-like, you have more time as you go into dream sleep. Why would this be? If you look at rats running around a maze as they learn the maze, the memory centers of the maze code the maze. So it's sort of like,

• 28:46Speaker 02

  if you were to listen to the brain cells as it's learning the signature of the maze. And then scientists have let those rats sleep and then they've listened back into the firing of those brain cells. And what's stunning is that when you go into REM sleep, unlike non-REM sleep where things speed up, in REM sleep, it goes from

• 29:13Speaker 02

  it's about 0.5 times. It's like taking this podcast and hitting on your podcast player, play it at 0.5 times for me. That's what dream sleep is actually like and maybe provides an explanation for why we have time dilation and why you can create beautiful movies like Inception.

• 29:33Chuck Nice?

  And now, at what level, at what level does it go to?

• 29:37Speaker 02

  The one that I'm most worried about is the one that goes

• 29:47Speaker 02

  I'm trying to be fitting with the

• 30:07Gary O'Reilly?

  All right, Matt, how about premonitions? Because I've got into this before about a premonition I've had. But do we have the ability to see into the future while we dream? Or, quite literally, are we just dreaming? The answer is no. No. It's no.

• 30:21Neil deGrasse Tyson?

  No.

• 30:22Speaker 02

  Really?

• 30:23Neil deGrasse Tyson?

  We want it to be true. Books are written about it. It's in, it's in religious texts.

• 30:29Speaker 02

  Oh, Neil, I'm so glad you are in the world. Um, well, at first glance, you're right. And then if you look at some of the data, you start to think, ah, is he right? Because there are some cases where people, and this is what people will tell me. Say, look, the FBI has a documented person who, two days before, called them and said, look, there is going to be, unfortunately, a plane crash. It's going to be, uh, you know, this specific line, and it's going to crash in this state. Um, it's going to crash here in the United States. And they think, you know, it's a crackpot and yeah.

• 31:11Neil deGrasse Tyson?

  And the FBI should arrest that bomber.

• 31:13Speaker 02

  They just think this, this person is, is out of their mind. And then lo and behold, you know, two days later, and now that person seems like a culprit, and they find out that it's not. How is that, that seems deeply prophetic. When that person then tells you during the interview, I had this dream, it was a dream that told me this was going to happen. It felt so real. And now I've just seen it happen and I want to go back to my phone call. And you think, okay, there's got to be something in this. Well, this is where there are lies, damn lies, and statistics. Because if you think about firstly, we have about four to five REM cycles every night. And let's just say that for every REM cycle, we only have one dream.

• 31:55Speaker 02

  It's probably not true, but let's be conservative in our calculation. So that's about four to five dreams per person, per night, across the current six billion human beings. So if you do.

• 32:10Neil deGrasse Tyson?

  Eight, eight.

• 32:12Speaker 02

  Eight billion, right. And let's assume that of those, you know, seven are at the stage of development where they actually are dreaming. So I become conservative again. That math, that mathematics, as we would say, if you calculate it means that it is highly probable by just statistical chance alone that someone somewhere on the planet tonight is going to have a dream that turns out to have some degree of prediction of something that will happen in the world tomorrow. It is just statistical chance. Unfortunately, Neil, you're a gem. You're absolutely right again.

• 32:50Neil deGrasse Tyson?

  And we remember the hits and not the misses, right? Do you call up the FBI every time you have some kind of crime premonition? You know, it's.

• 33:00Chuck Nice?

  I had a dream that someone killed my wife and it has not happened. What is going on? What is happening?

• 33:08Speaker 02

  Why I can't get away with this.

• 33:10Gary O'Reilly?

  Oh, you're in so much trouble with the good lady. So you've bust that miss by statistics and damn lies, in my opinion, man. So when we enter a dream state and we sleep, is there a point where we are entering into a psychotic state?

• 33:29Speaker 02

  By all definition, yes. Because when you start to dream, you begin to see things which are not there. So you're hallucinating. You believe things that couldn't possibly be true. So you're delusional. You become confused about.

• 33:44Neil deGrasse Tyson?

  Like the monster chasing me, right?

• 33:45Speaker 02

  Correct. You know, and that feels immensely real. And you ask your heart rate and it will confirm that very much, you know. And so, and you lose your sense of time, place and person. So you're suffering from disorientation. You have wildly fluctuating emotions that we call being affectively labile. And then how wonderful, you woke up this morning and you forgot most, if not all of that dream experience. So you're suffering from amnesia.

• 34:13Neil deGrasse Tyson?

  What does that phrase mean?

• 34:15Speaker 02

  Labile means unstable, almost pendulum like in an unpredictable manner where you're just unstable. So it's a very labile state. And in that way, you know, across all of those five things, hallucinating, you're delusional, you know, you're, and you're amnesic. If you were to report any one of those symptoms when you're awake to me, you know, you would be seeking serious psychological psychiatric treatment. But for reasons that were now only just understanding, it seems to be both a perfectly normal biological and psychological sleep, but you are essentially entirely psychotic when you dream.

• 34:57Chuck Nice?

  Nice to know.

• 35:00Chuck Nice?

  It's good to see that things don't change when I go to sleep.

• 35:03Speaker 02

  P S, you're welcome. You know, you invite a guest onto the show and what they end up doing is accusing you of becoming utterly psychotic. Thanks. Great.

• 35:14Neil deGrasse Tyson?

  I got a question. In zero G, you know, I think of a nice cozy night's sleep. It's a fluffy pillow, nice cozy comforter blankets. In zero G, your body doesn't lean in any one direction. You just float there. So does you think your brain know, I mean, we have, you can ask astronauts this, of course, but I've never, I never thought to do so. Does your brain have to have some sense of a gravity vector while you're asleep, do you think?

• 35:45Chuck Nice?

  Yeah, like, like your inner ear.

• 35:47Neil deGrasse Tyson?

  Yeah, for proper, for proper dreaming.

• 35:49Speaker 02

  Yeah, it's a fascinating question. And, you know, we've done some work with, with NASA with sleep. And it's, it's a, it's a really important challenge for a number of reasons. But firstly, what we found is that that gravitational vector, as you described it, isn't thankfully hugely influential such that any one particular stage of sleep or your entire sleep becomes un, ungeneratable, as it were, not a word, but it's not necessarily a problem there. However, there are some other problems. The first is just simply pragmatic, that if you are floating around and you're asleep, you're going to start

• 36:33Speaker 02

  bumping into things, you're always going to be waking up. So firstly, you have to carabiner yourself against this.

• 36:39Neil deGrasse Tyson?

  They strap them in on the, not just bodies floating by.

• 36:43Speaker 02

  Well, you know, the people who are working the night shift, the, the typing way there, who's that? Oh, it's Gary floating by, you know?

• 36:51Neil deGrasse Tyson?

  And the people who snore, you know, there's extra propulsion.

• 36:55Speaker 02

  Correct, yeah, could you imagine? Well, actually, it would be great because what you could do is, is you could sort of, since there's no gravity, hopefully that means that you could not have the airway collapsing and snoring would be less. That's actually a really interesting hypothesis, one that I don't know.

• 37:13Neil deGrasse Tyson?

  Is there snoring in space?

• 37:15Gary O'Reilly?

  Yes. These are the questions we need answers to.

• 37:19Speaker 02

  Great hypothesis. I love it. There's the first grant. But yes, so you have to carabiner yourself against this sort of large cylindrical metal cigar that you're floating around. And that's the first thing. The second weird thing is that when you, in sort of zero G, when you exhale, if there wasn't sufficient circulation and you're strapped in and you're in the same position, what begins to happen is you get this buildup, this cloud of carbon dioxide around you.

• 37:49Neil deGrasse Tyson?

  A CO2 bubble.

• 37:50Speaker 02

  CO2 bubble. And it can obviously lead to a very quick final popping you out of the gene pool.

• 37:56Neil deGrasse Tyson?

  Asphyxiation. Just to be clear, the space station has air currents in it. So it would, it would cycle through the air. And other than the CO2 coming out at body temperature, which is presumably warmer than air temperature. It would rise away from you. It would rise on Earth and not rise in the space station. So, but so that's, there is dark, there are air currents. And so much so that if you leave something, if you let something go, it'll eventually go to the vent, right? So that's why everything's Velcroed in.

• 38:30Speaker 02

  Yeah, nice.

• 38:31Neil deGrasse Tyson?

  If you misplay something, check the vent.

• 38:33Speaker 02

  Yeah.

• 38:34Gary O'Reilly?

  So, Matt, you know, talking to the space station, how many sunsets and sunrises do you get in space in a, in a 24 hour period for an astronaut or on a space station? And how are you working with that?

• 38:47Speaker 02

  Here's the challenge. This is the main reason, not the loss of the gravitational vector, but the fact that your circadian rhythm that we spoke about is now thoroughly confused. Because let's say that you're on the International Space Station as, as an example. You are going to see every 24 hours. Sixteen sunrises and sixteen sunsets. And so your body is getting the signal that we all get in a nice predictable fashion. Once during the day, once sunrise, one sunset. It's getting the signal of, okay, it's time to be awake. Um, oh, no, now it's it's the, oh, no, and you're awake. And no, no, no, back to sleep.

• 39:27Neil deGrasse Tyson?

  But Matt, how how connected are we to the sun? We we live in a fully lit nighttime. I live in New York City. You know, it it doesn't get dark.

• 39:38Chuck Nice?

  I I never take my eyes off my phone.

• 39:40Neil deGrasse Tyson?

  So I mean, I mean, you know, are we farmers? No, you know, we're not all just up, time to go, go to sleep. The sun is setting, time to wake up. So do we think it really matters anymore in modern society? I'll still give you the 24 hours, but do you really give a rat's ass about the sun anymore?

• 39:59Speaker 02

  You you would think based on.

• 40:01Gary O'Reilly?

  I'm not sure I heard you say that, right? You give a rat's ass about the sun.

• 40:05Neil deGrasse Tyson?

  Take that song.

• 40:07Speaker 02

  Yeah, well, speaking speaking about the rodent derriere, as you just described it. Um, I, yes, it does matter. And in fact, it's part, it's one of the contributing reasons why there is so many, um, or there's so much sleep disruption and sleep problem, such a sleep problem that we see in society right now. We have become dislocated from this natural edict of the rising and setting of the sun. We are a dark, deprived society in this modern era, and we need darkness at night in particular to help regulate the hormone release called melatonin, which augments your human sleep.

• 40:51Speaker 02

  And in part, we can do this with natural light when we come in in the evenings. No wonder we are sleep disrupted because our brain is thoroughly confused. It's in constant low level light.

• 41:02Neil deGrasse Tyson?

  I really have a couple more minutes. Matt, I I might be a good subject for your sleep studies because I can sleep anytime, anywhere, in practically any position for almost any length of time. So much so that I would say, you know, the power nap that people talk about? I I I can either have that or not. If I got a couple of minutes, I I say, let me sleep for 20 minutes and I'll get up and go. Let me sleep for an hour and a half. Let me sleep for 45 and I'll do this. And. At night, I can sleep for eight hours or five hours, depending on what I need to do in that day. So, and I can go to sleep within minutes of laying down, you know, in some kind of comfortable position. And I met so many people that have a hard time sleeping.

• 41:47Neil deGrasse Tyson?

  I say, what do you mean you have a hard, just go to sleep?

• 41:49Speaker 02

  Right.

• 41:50Neil deGrasse Tyson?

  Or stay awake and do something productive. Don't lay in bed, so I can't get to sleep. Then go do some, mow the lawn. I mean, so, so.

• 41:58Gary O'Reilly?

  Yeah, 11:30 at night, get the lawnmower out. Your neighbors are gonna love you.

• 42:03Neil deGrasse Tyson?

  Am I, is it true that people who sleep anytime, anywhere, and, and I don't drink coffee, I don't have a relationship with caffeine, so I don't depend on that for me to be awake or asleep? Is this, I, I think that's unusual based on people I speak to.

• 42:17Speaker 02

  It is unusual, and it's especially unusual the older that you get. I'm not suggesting that you're old, but as we get older.

• 42:23Neil deGrasse Tyson?

  No, I'm an old fart. I'm an old crusty man right now.

• 42:26Speaker 02

  Trust me, I'm, I'm right there with you in the foothills of middle age at least right now. Um, it is inbound. What we, what I would say is that firstly, you could just be one of those unique people who have an incredible appetite and hunger and drive for sleep, such that the alacrity of your sleep with which it arrives is stunning and that you're in the top 1%. The other thing that sometimes we would want to do, however, is check the quality of your sleep. Because if you are constantly able to fall asleep anytime, anywhere, for any duration, which is what you just described to me, at that point, I may be getting a little bit worried that you're carrying a lingering sleep quality

• 43:10Speaker 02

  debt, because there's something about your sleep that may not be quite sufficient, such that with that debt, you are constantly craving, your brain has this constant hunger because you are constantly in a fasted state, as it were, when it comes to quality sleep. So no wonder whenever you give your brain the chance, it thinks, time to feast, because my goodness, I'm so sort of sleep macro nutrient deficient right now.

• 43:38Neil deGrasse Tyson?

  Giving it the little bit that it'll take.

• 43:40Gary O'Reilly?

  Or it could have been that she's just a closet narcoleptic.

• 43:43Neil deGrasse Tyson?

  No, I. I mean, so, so, but also when I wake up, I'm pretty perky when I wake up. I'm not one of these.

• 43:51Speaker 02

  That's right. Yeah, and there is, unfortunately, there is not necessarily a strong alignment between your subjective sense of how well you slept last night. So I would say that when it comes to that sleep need, we would just want to check the quality of your sleep to make sure that you're sleeping okay. And if that's the case.

• 44:11Neil deGrasse Tyson?

  Well, next time in Berkeley, put me on electrodes, okay?

• 44:14Speaker 02

  I will bring you in anytime. We'll fly out. We'll, we'll come and apply them tonight. Tell me where you live. And once I know where you live, oh, be careful.

• 44:26Neil deGrasse Tyson?

  Well, Matt, this has been a delight. Neil deGrasse Tyson here, coming from a StarTalk special edition on sleep. We'll see you again, provided you continue to look up.