The Definitive Guide To Sleep | Dr Greg Potter

Dr Greg Potter is a PhD graduate at the University of Leeds & Content Director at HumanOS. His research focus is on sleep and chronobiology; looking at circadian rhythms, light-dark cycles and the potential for meals to entrain peripheral circadian clocks. The unsung hero of health is hiding under our pillow every night and today we learn just how important a good night's sleep is to our short & long term fitness, our mood, cognitive output, physical performance, injury risk, weight and pretty much everything else. Discover the best approach for dealing with sleep deprivation, how to optimise your sleeping environment, how meal content & timing can affect our circadian rhythms and a lot more. Further Reading: Follow Greg on Twitter: https://twitter.com/gdmpotter $1 for 1 month of Premium Membership at: https://www.humanos.me/ (Code: modernwisdom) - Listen to all episodes online. Search "Modern Wisdom" on any Podcast App or click here: iTunes: https://itunes.apple.com/gb/podcast/modern-wisdom/id1347973549 Spotify: https://open.spotify.com/show/0XrOqvxlqQI6bmdYHuIVnr?si=iUpczE97SJqe1kNdYBipnw Stitcher: https://www.stitcher.com/podcast/modern-wisdom - I want to hear from you!! Get in touch in the comments below or head to... Twitter: https://www.twitter.com/chriswillx Instagram: https://www.instagram.com/chriswillx Email: [email protected]

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

• 0:00Chris Williamson?

  Hi friends. How was your night's sleep? Was it good? Hopefully after today's episode, it's going to be better.

• 0:10Chris Williamson?

  Today, we're going to speak to Dr. Greg Potter, who is a PhD graduate from the University of Leeds and a specialist in sleep. His work has been featured absolutely everywhere, from Reuters to Time Magazine, Washington Post, USA Today, Daily Telegraph, BBC Radio. He's, um, he's pretty prolific and he's also the content director at humanos.me. Now, the guys at human OS haven't sponsored this episode at all. However, it is a fantastic service that you should check out. And later on in the episode, Greg explains what it's all about. But if you do want to go and have a look, it's free to sign up.

• 0:54Chris Williamson?

  And with the code MODERNWISDOM, you can actually get their premium version for $1 for the first month and there's no minimum term. So check it out. Now, many people take a lot of time researching their diet or their exercise and making sure that they're trying to live a healthy life. But quite a lot of us overlook just how important sleep is in this equation. And having read Matthew Walker's book, Why We Sleep, I was struck by just how little care I was giving to my sleep habits. The implications on your health, mood and performance, both in the short and long term are pretty drastic.

• 1:38Chris Williamson?

  And I don't think that there can be enough weight applied to just how important sleep is. Now, hopefully today, we're going to convert you from a non-believer to a sleep paragon, who is armed with some new tools to improve their sleep and a passion to actually make it better. Essentially, what I'm saying is that if you live a long and healthy life with all of your faculties still intact, at the ripe old age of 95, you can be on your deathbed incredibly mobile and full of zen and look back at this podcast and think, "Thanks, Chris and Dr. Greg."

• 2:35Chris Williamson?

  Dr Greg Potter, welcome to Modern Wisdom.

• 2:38Speaker 01

  Thanks very much. It's great to be here.

• 2:40Chris Williamson?

  How are you today?

• 2:41Speaker 01

  Yeah, I'm very well. How are you?

• 2:43Chris Williamson?

  Fantastic, thank you. Did you get a good night's sleep?

• 2:46Speaker 01

  Not bad. Been up for a while.

• 2:48Chris Williamson?

  By, by whose standards did you have a not bad night's sleep?

• 2:52Speaker 01

  By my own not particularly good standards, right?

• 2:58Chris Williamson?

  Rigorous sleep standards, right?

• 3:02Speaker 01

  Well, I didn't set the bar too high, but the last few weeks have been a bit ropey at times.

• 3:06Chris Williamson?

  Is it do as I say, not as I do?

• 3:09Speaker 01

  Yeah, it's one of those.

• 3:12Chris Williamson?

  So can you explain to the listeners what your speciality is, what you're, what you focus on in your research area?

• 3:21Speaker 01

  Sure. So I have just passed my PhD.

• 3:25Chris Williamson?

  Congratulations.

• 3:27Speaker 01

  Thank you very much. Which was at the University of Leeds and I'm in Leeds right now. And during my PhD, I focused on sleep, diet and metabolic health in UK adults. So I focused on studies of human beings and in my PhD, there were several different parts. It began with the validation of a dietary recall method. So if a nutritionist is interested in how diet affects health and risk of various diseases, then they need accurate ways of capturing what somebody eats. And to that end, you need to validate the tools that you use.

• 4:08Speaker 01

  And I was involved in the validation of one of those tools, which is called MyFood24. And it's the first validated tool designed for you specifically with adults in the UK. It's very comprehensive and that paper is just being published. And I then used that data set to look at associations between when people eat relative to when they sleep and their metabolic health. I also did some work looking at how sleep duration is associated with. Risk markers that are associated with diabetes in the UK and also with how people eat. And then at the end of my PhD thesis, I did a randomised control trial of

• 4:51Speaker 01

  long-term melatonin supplementation among people who are at high risk for type two diabetes. So let's say, for example, Chris, that your dad has type two diabetes, that would increase your susceptibility to that disease. Question was, can you use melatonin as a prophylactic agent against you developing type two diabetes? So just wrapped all of that stuff up and now I work for Human OS as content director. And have been working with those guys for about the last eighteen months or so. And have more or less been working full time for the last four months.

• 5:30Speaker 01

  And the CEO also has a strong background in sleep research, so we share that in common, but.

• 5:37Chris Williamson?

  You're in good, you're in good company then.

• 5:40Speaker 01

  Yeah, I would say so, for sure.

• 5:42Chris Williamson?

  That's fascinating. Well, I mean, there's, there's an awful lot, an awful lot to go through there. But I know that a lot of the people who are listening will have heard me mention a number of times Matthew Walker's book, Why We Sleep. Um, I think that's probably up there with my most ever listened to podcasts between him and Joe Rogan. And it's going to be, it's going to be really, really interesting to be able to dig into what I've heard um, and, and read about so much and, and try and actually um, elicit some of the answers that I think are maybe missing from my body of knowledge. And then give the listeners a little bit more, a little bit more of an understanding of why sleep's important and, and, and what it does to people. And then I'm super excited to talk about Human OS as well.

• 6:23Chris Williamson?

  I earlier on today had a, a pretty comprehensive browse of the, of the site, so we'll be able to finish up with that at the end. So a lot to get through today.

• 6:31Speaker 01

  Smashing. Sounds good.

• 6:33Chris Williamson?

  Fantastic. Um, so to get started, do you know why we sleep?

• 6:40Speaker 01

  No, not really.

• 6:42Chris Williamson?

  That's great.

• 6:44Speaker 01

  So it's a longstanding question in sleep research and there are many different ways that you can try and address it. What I would say is that there's no real consensus right now. And I think it's worth thinking about why we sleep from evolutionary perspective. And when you think about sleep, and this is something that Matt discusses at length and with great clarity in his book, sleep's very strange in that while you're asleep, you can't eat, you can't gather food, you can't have sex, and you're vulnerable. And for all of those reasons, there should have been very strong evolutionary pressure against the development of sleep-like behaviour.

• 7:24Chris Williamson?

  You're incredibly vulnerable, right?

• 7:26Speaker 01

  Yeah, absolutely. But as far as we can tell, more or less all species studied have sleep-like behaviour. We spend a third of our lives doing it. So the question is, why is that the case? And I think that in reality, it probably serves different functions in different species. What's interesting is that different organisms have very different sleep patterns, both the timing of their sleep and also how long they sleep. And there are various things that seem somewhat predictive of sleep. So things like the complexity of social networks, nervous system complexity, the type of diets that animals consume. But no one thing is strongly, is a strong determinant of sleep in animals. So anyway, what happens

• 8:11Speaker 01

  during sleep? Well, it's a period of adaptive inactivity. And one of the functions is probably to optimise the timing and duration of bouts of activity to do things like reduce the risk of predation, and also to ensure food acquisition. Another function is energy conservation. But actually, if you look at the amount of energy that you save by sleeping versus just being awake and relatively inactive, it's very, very small. So that's not a particularly persuasive.

• 8:41Chris Williamson?

  So evolution hasn't given us this because it lowers our requirement for food?

• 8:45Speaker 01

  Doesn't seem to be the case. Not in humans. If, for example, you look at all of the studies that have been done on the effects of sleep restriction on energy expenditure, the effects are negligible. We're speaking about the amount of energy that's contained in a slice of bread.

• 9:03Chris Williamson?

  Just have another, have another bit of bread, you'll be fine, honestly.

• 9:08Chris Williamson?

  Stay up all night, off your face on bread, and then the next day you'll be fine.

• 9:14Speaker 01

  Well, bread has gluten in it and that will probably get.

• 9:16Chris Williamson?

  Oh, no. I'm gonna trigger everybody.

• 9:24Speaker 01

  So anyway, there are also different things that we pass through during sleep and each of those serves related but distinct functions. So if, for example, you look at non-REM sleep, non-REM meaning non-rapid eye movement, there are three stages of this type of sleep, each of which becomes progressively deeper, by which I just mean that it's harder to wake someone. Non-REM sleep, there are processes like nervous system restoration, energy conservation, and pruning away connections in your brain that you used during the day, but weren't highly used and therefore don't seem to be necessary to hold on to. During this stage of sleep, there's also a kind of waste disposal system that becomes active in the brain.

• 10:07Speaker 01

  And there was a study that was published about five years ago showing that during sleep in mice, the plumbing in this system effectively opens up and cerebrospinal fluid washes toxic debris out of the spaces in the system that's accumulated during the daytime. So that seems to be one of the functions of that particular type of sleep.

• 10:24Chris Williamson?

  Does that, does that explain an increase in clarity of thought the next morning after you've had a good night's sleep to one degree?

• 10:31Speaker 01

  Yeah, it would do. It would do, absolutely. And then another stage of sleep that you'll enter after that deepest stage of sleep is the stage with which most people are most familiar, rapid eye movement sleep, which is that stage in which you dream. It's called rapid eye movement because of the ways that your eyes dart from side to side during this stage. It's quite strange in that even though parts of your brain are as much as 30% more metabolically active at this time than they are during wakefulness, your muscles are completely paralyzed so that you don't act out your dreams.

• 11:04Chris Williamson?

  Yeah.

• 11:05Speaker 01

  What this creates is environments in which you can take information that you've. Accumulated during the day and then consolidated during deep sleep. And you can collide all these different sources of information in your brain to form new connections. And through those new associations, you seem to be able to generate creative ideas. And what's very interesting actually is that if you look at humans specifically, then we spend maybe twenty to twenty five per cent of our sleep in REM sleep, which is more than any other primate, but we sleep less than any other primate. And some people speculate that this disproportionately large amount of REM sleep that we have as humans

• 11:50Speaker 01

  has been fundamental to the development of our intelligence and our complex social structures. So that's quite interesting.

• 11:58Chris Williamson?

  That is interesting. I'd I'd seen the study that you're talking about to do with, or want a study that related to new connections in the brain when you're asleep. And recently did a podcast with the author of Make It Stick, Peter C. Brown. And during that, he said that one of the key determinants of your capacity to learn is doing focused, concentrated work and then going away from it and then coming back. And I think that that generating new connections and viewing, um. Anecdotally, you'd say you're viewing something with a new perspective, but it seems that that's actually being reflected physiologically within the brain.

• 12:41Speaker 01

  Yeah, and there are probably a couple of things to touch on there. So one is learning during the day and the importance of spacing because it's been years and years, more than a decade since I looked at any of this research. But in psychology, there are so-called primacy and recency effects, which just means that you tend to remember what you learn at the start of a learning bout and the end of it too. And you don't remember the stuff in the middle so much. So what that means is that, let's say that you've got six hours in which to learn. You're better off taking regular small breaks and then by doing so you create more opportunities for these primacy and recency effects and then while you're not doing

• 13:26Speaker 01

  learning, you want to take your mind entirely off the task. So that's one component to the puzzle, but another component to the puzzle is sleep out during learning or between learning periods themselves. And I don't, this is something that you want to return to later, but the, the way that that happens is relatively well understood. There are specific aspects of the process that are controversial and there's not complete consensus on, but it's something that's probably worth understanding because actually it is information you can use to improve your ability to, to learn.

• 14:08Chris Williamson?

  That's fascinating. Is the, is the sleep, um, industry of researchers, is it quite dogmatic? Are there some pretty sort of, uh, standoffish camps? I don't know how militant the, uh, the sleep world is.

• 14:24Speaker 01

  Well, you're speaking about a bunch of academics and I would put them quite firmly in the passive category as individuals.

• 14:32Chris Williamson?

  Okay.

• 14:33Speaker 01

  Never seen a fight at a conference. But with that said, that there is contention over some things and I think that it's often the case that somebody's view will be ingrained early on and then it will go a period of time without being challenged.

• 14:50Chris Williamson?

  Yep.

• 14:51Speaker 01

  And there's been this so-called replication crisis in science recently and it's received an awful lot of attention in the media. I think psychological research in particular has come under fire for the inability to reproduce the results of previously done studies. And what's nice now is that more and more journals are necessitating that people make their data open access after publishing. So people can revisit what other scientists did to make that they did in fact do what they said they did and to make sure that they haven't dredged through their data and tried to.

• 15:34Speaker 01

  Come up with a way of analysing their data to support their hypothesis, rather than going in there beforehand and saying, okay, this is how I'm going to look at my research question. And regardless of what the results are, I'm sticking to my guns.

• 15:49Chris Williamson?

  Well, that's the, that's the scientific principle, right? You shouldn't be trying to make the research fit a previously held hypothesis. That's not the way that it's supposed to be. But I can imagine that a lot of people, once they've got their teeth, once they're certain about something conceptually, they want the research to then reflect that.

• 16:06Speaker 01

  Yeah. And an issue is that it's difficult to publish negative findings in scientific journals. By negative findings, I don't mean that they're disheartening or anything like that. I mean, there's no effect of A on B.

• 16:22Chris Williamson?

  Yeah.

• 16:22Speaker 01

  And

• 16:23Chris Williamson?

  It's less, it's less glitzy, right? It's not as much of a, melatonin doesn't, doesn't affect sleep quality, isn't as much of an exciting title. That might actually be, but something else that A doesn't affect B, it's not as attention grabbing, right?

• 16:39Speaker 01

  Yeah, it's not going to get on the front page of the Washington Post anytime soon.

• 16:43Chris Williamson?

  I got you. So we understand, oh, we have a beginning of an understanding of what we think sleep is required for from an evolutionary perspective.

• 16:52Chris Williamson?

  Do we know how much is optimal? Is there an agreed upon time? It's kind of this wives tale anecdote that eight hours is how much we need a night. Is that, is that correct?

• 17:04Speaker 01

  There are guidelines, but you can't take the guidelines and assume that you're correct, that they are correct for you as an individual. The guidelines vary according to how old somebody is. So if you look at young people, they need more sleep than adults. And for adults, according to the National Sleep Foundation, on average, we need seven to nine hours per night. But there is relatively substantial variability between people in sleep need. And one other thing that I'll add is that The amount of sleep that you need is a moving target.

• 17:44Speaker 01

  So I don't know what your experience is, but for me, for example, I generally find that I sleep more in the winter than I do in the summer. And I think that's probably somewhat related to the photo period. Also, if I'm going through a period in which I'm exercising particularly intensively, then I'll need more sleep. If I have a cold, then I'll need more sleep. If I'm stressed about something and I have a deadline on the horizon, then it's just as if the alarm clock in my brain just comes online a little bit earlier.

• 18:14Chris Williamson?

  Yeah.

• 18:15Speaker 01

  For that reason, invariably, I sleep less. So even though we have these generic targets, I think that actually fundamentally, you give yourself the opportunity to get the sleep that you need by getting in bed on time. You focus on preparing for sleep as well as possible by getting in the right framed mind and also supplying with your body with what it needs, ensuring that your environment around you is conducive to good sleep. And then you don't wake up to an alarm and you see how long you sleep. And it it sounds facile to explain that way, but I I do think that that is how it is.

• 18:58Speaker 01

  With all of that said, seven to nine hours is a good baseline for most people. And we understand more and more about some of the things that do influence why some people need more or less sleep. But some people, I think historically, have thought that there are those lucky few out there, the Margaret Thatcher's of the world, who need three hours of sleep and they function just fine. And that just doesn't seem to be the case. So of all of the genetic variants that have been identified so far, the particular variant that's associated with the short asleep phenotype is on average a variant that has adult sleep about.

• 19:41Speaker 01

  Six point two hours per night, which I think is probably far more than most people would expect the shorter sleepers to sleep.

• 19:50Chris Williamson?

  Is that the phenotype which is present in the same percentage of people that get hit by lightning? Is it the incredibly rare one?

• 19:58Speaker 01

  Yeah, that sounds about right.

• 20:00Chris Williamson?

  Is it? I think it's one in one hundred and twenty thousand or something like that.

• 20:04Speaker 01

  It's very rare, yeah.

• 20:05Chris Williamson?

  Right, so I think it's safe to assume that you don't have that. For the vast majority of people that are listening. So what that means is you need to be aiming for between seven and nine hours. And just how important is sleep to our short term and long term health?

• 20:25Speaker 01

  That's a very big question.

• 20:29Speaker 01

  Okay, so so where would you like me to start with that? We can speak about metabolism?

• 20:33Chris Williamson?

  Or? Let's take it from the top, wherever wherever you think's best to set the scene and go from there.

• 20:39Speaker 01

  Okay. Well, I suppose there are different ways of looking at it. Obviously, you can't have an intervention in which, over a very long period of time, you have one group of people shorten their sleep and you have another group sleep as much as they like. So in order to get at the effects of sleep on the population level, people use epidemiology, the study of populations. And typically, those types of studies will just have people answer questions about sleep. And then researchers will associate how long people report sleeping with various health outcomes. And preferably, they will also follow them up over time. So in those circumstances, prospective studies like that can be used to see whether short sleep at

• 21:23Speaker 01

  baseline predicts greater development of chronic disease further down the line, for instance.

• 21:29Chris Williamson?

  Okay.

• 21:30Speaker 01

  So that's that's one way of looking at things. The problem with that is that there are all sorts of confounding variables. So.

• 21:35Chris Williamson?

  It's self it's self reported, right? It's hardly a scientific approach.

• 21:40Speaker 01

  Well, it is a scientific approach, but it's not objective.

• 21:43Chris Williamson?

  Okay.

• 21:44Speaker 01

  That's the point. And in order to get a more objective handle on the effects of disrupted sleep on various outcomes, you need to look at sleep studies in which people come in the environment, into the laboratory environment. And they are given a certain amount of time in bed and then you assess various outcomes of interest. So if we start with metabolism, for example, then we've known for about twenty years now that as little as five nights of shortening somebody's sleep to four hours per night results in otherwise healthy young people temporarily becoming pre-diabetic.

• 22:27Chris Williamson?

  Wow.

• 22:29Speaker 01

  Not only that, they also tend to eat differently. So that effect is seen when somebody's diet is held constant. But if you let people choose what they eat, then on average, restricting somebody's sleep duration to a period of, say, four to six hours per night tends to increase the amount of energy they consume by about three hundred and eighty-five calories a day.

• 22:52Chris Williamson?

  Okay.

• 22:53Speaker 01

  Which doesn't sound like much, but of course, health is the consequence of your behaviours over a long period of time. So the cumulative effect of all of these small impacts adds up to something meaningful. And three hundred and eighty-five calories a day over the course of a year, that's the amount of energy that's stored in about eighteen kilograms of fat tissue.

• 23:21Speaker 01

  I'm not saying that you would gain eighteen kilograms of fat tissue because you have this lipostat in your brain which will actively try to defend how much fat you carry, so it's relatively unwavering. But you are likely to gain weight, let's put it that way.

• 23:36Chris Williamson?

  So sleeping less means eating more. And I'm gonna presume that people, when they are tired, I know for myself, if I've had a really bad night's sleep, or if I haven't slept enough, I'll reach for less healthy foods as well.

• 23:52Speaker 01

  That's exactly right. Yeah. So it's not only the amount of food that people are eating, but it's also the quality of food that seems to be affected by sleep loss. And in the last maybe decade. People have started to look at the effects of sleep loss on patterns of activity in the brain in response to food stimuli. So for example, you can have somebody come into the lab, you can completely deprive them of sleep over the previous evening and then show them images of cupcakes and cookies. And you can compare their brain activity in that situation to when they're allowed as much sleep as they would like. And after the sleep deprivation,

• 24:31Speaker 01

  areas of the brain that are involved in motivation and reward to acquire food lights up like a Christmas tree. And not only that, but the prefrontal cortex, which is the most recently evolved area of the brain, you can think of it as the brain CEO or the part of the brain that lets you do the right thing when it's the more difficult thing to do, is less well connected to other regions of the brain. So it doesn't have the ability to override those urges. And some of the more primitive parts of the brain in the limbic system tend to be more active too. So you have this double whammy of brain activity

• 25:10Speaker 01

  that makes it increasingly hard to avoid succumbing to the temptations of things that our bodies are hardwired to gravitate towards, like lots and lots of calories.

• 25:23Chris Williamson?

  That's interesting. So I know a lot of my friends that do sports and some of them will be prepping for bodybuilding competitions, fitness shows, CrossFit competitions that are coming up, specifically when they're in a deficit, if they're dieting hard, trying to cut before a show, I know that they struggle with their sleep. So what you're saying is that the poor night's sleep that they've potentially got, perhaps because of being hungry, or perhaps just because of stress about the show, or whatever it might be, is making the next day of deficit eating even more difficult and requiring even more willpower to not go and get a cookie from the cupboard.

• 25:59Speaker 01

  Yeah, unfortunately, that is a vicious cycle.

• 26:01Chris Williamson?

  That is a very, very vicious cycle. So apologies to the guys that are getting ready for shows that are listening, but you just need to go to bed a little bit earlier, I think. So what about the effect of sleep on mood?

• 26:17Speaker 01

  So if you look at sleep duration and neurodegenerative disease and also various mood disorders, bipolar disorder, major depression, there seems to be strong associations there. So it appears to be the case that almost no mood disorder, in almost no mood disorder, people experience normal, healthy sleep. There's always some sort of disruption. And what I'm most familiar with is the effects of circadian system disruption on mood and also how circadian rhythms are misaligned in certain mood disorders.

• 27:02Chris Williamson?

  Can you briefly explain what a circadian rhythm is for us, please?

• 27:05Speaker 01

  Sure. So organisms evolved in this 24-hour light-dark cycle that we experience each day. Not only that, that's nested within the context of the seasonal changes in various environmental conditions. And to thrive in those environments, they needed to develop timing systems to help them anticipate daily changes in the environment, change in temperature, change in light exposure, because with that came changes in food availability and predation risk and so on. And over the course of millions of years, almost all, not all organisms, evolved

• 27:46Speaker 01

  these internal timing systems. And a circadian rhythm is a rhythm that has a period of about 24 hours, but it's not precisely 24 hours. These rhythms are self-sustained, so they repeat of their own accord, day after day. They're persistent and they're untrainable. So because they're not exactly 24 hours, they need to be reset each day. And the strongest entraining agent in the environment that resets our biological rhythms as humans is the light-dark cycle. And that does so by way of, it's called the photoneuroendocrine system, but it's just...

• 28:31Speaker 01

  The way that light is perceived by specialised cells in the eyes. And these specialised cells then relay information about light exposure to a so-called master clock in the suprachiasmatic nucleus in the hypothalamus. And this master clock just sits atop where the two optic nerves that come from the eyes to the visual cortices is placed and it samples information about the light environment. Over time, it then knows what time of day it is outside roughly, and it uses various ways of sending this time of day signal elsewhere in the body. So perhaps the best known of those is via

• 29:12Speaker 01

  the pineal gland and subsequently melatonin synthesis. So as light comes into your eyes, this signal is then transferred back to the pineal gland via the master clock. And light exposure offsets melatonin synthesis. During darkness, that signal is no longer coming in, so the pineal gland synthesises melatonin. And then melatonin relays this signal of darkness throughout the body because many of your body's tissues have their own melatonin receptors. And through that mechanism, they know that it's dark outside and they should be performing night time activities. But it's not only melatonin that the system uses, it also uses things like

• 29:56Speaker 01

  changes in body temperature each day. Another very important hormone in the circadian system is cortisol. And if you look at the daily rhythm of cortisol, then in anticipation of waking each day, you see this big spike in cortisol in healthy people. Maybe an hour or so before waking up. And what that does is mobilises stored energy reserves in things like your muscles. It increases your blood pressure, your heart rate, and it readies your body for the day ahead. So that's one other key agent. And then the master clock itself also sends out or secretes its own.

• 30:37Speaker 01

  Substances that then reach other areas of the brain and help coordinate the timing of all these different body systems. So the circadian system as a whole optimizes your body for the needs of the present moment. And in this way, for example, you will be at your strongest during the daytime, your digestive system is best set to digest food during the active period, and at nighttime, your appetite will naturally wane. You'll have a drop in core temperature and brain temperature, and that improves your ability to fall asleep. You will see a spike in growth hormone, which will help you preserve your lean body mass overnight.

• 31:17Speaker 01

  And overall, the net effect of this symphony, if you like, is to make sure that if everything is working properly, then your whole body is optimized for the needs of the present moment.

• 31:33Chris Williamson?

  Okay, so that's what a circadian rhythm is. I'm going to guess that that that requirement for light and dark to regulate our sleep is why seasons, specifically in places like the UK, where we do have quite a big disparity between summer day lengths and winter day lengths, I'm going to guess that that's one of the reasons that people may struggle to wake up in the morning or may find sleep different between seasons. Is that right?

• 31:59Speaker 01

  Yeah, it is. And there's not actually very strong evidence of seasonal differences in people's sleep patterns in artificially lit environments, because everywhere you go in the UK, you can't escape a street lamp.

• 32:15Chris Williamson?

  Yeah.

• 32:16Speaker 01

  Or light from buildings or whatever. But if you take people and you have them go camping during the winter, you have them go camping during the summer, then you will you will see quite rapid changes in people's sleep patterns that track changes in the light-dark cycle. And one thing that you mentioned there, which is relevant to mood disorders, to circle back to that, is how that changes over time and how some people may find it hard to wake up at certain times of year or just feel worse. So seasonal affective disorder, for instance, is quite commonplace, and it's more commonplace the further from the equator that you move, so at higher latitudes.

• 32:55Speaker 01

  And what you find is that around the time that we transition and the clocks switch back each autumn, you tend to see a spike in people who report experiencing depression at those times. And actually, the skating system is a point at which you can intervene in order to try to help those people. So.

• 33:18Chris Williamson?

  Do you think that that's, do you think that the reports of depression are to do with the single night of lack of sleep, or that that is a marker that the days are getting to a length where that would occur?

• 33:33Speaker 01

  Yeah, I, I think it's probably a bit of both, because.

• 33:35Chris Williamson?

  That's crazy that a single, a single change in time would elicit a, a response from, you know, a general population.

• 33:44Speaker 01

  Yeah, I, I, I think the strongest evidence of the change in time producing that kind of response is daylight savings time. So during the springtime, when we lose an hour of sleep each year, you tend to see a spike in traffic accidents at that time of the year, for example. There's also some relatively weak evidence that you might see an increase in cardiovascular incidents at that time, so an increase in things like heart attacks.

• 34:08Chris Williamson?

  Off the back of one night?

• 34:11Speaker 01

  Well, it's, it's one night acutely, but of course, people have to keep waking up early.

• 34:16Chris Williamson?

  Hmm.

• 34:17Speaker 01

  So let's say that the first night you lose an hour of sleep, and then you start to adjust to being a little bit earlier, but you never fully adjust. So maybe the second week, you're losing forty five hours of sleep, and the third, you're losing thirty minutes of sleep, and so on.

• 34:32Chris Williamson?

  Yeah.

• 34:34Speaker 01

  I think that there's, there's a cumulative effect there over time. So I think that's, that's probably the best evidence of that type of acute disruption to sleep having long term consequences for lots of people.

• 34:50Speaker 01

  But also that there is this change in photo period that seems to independently affect risk of people experiencing certain things.

• 35:01Chris Williamson?

  Okay.

• 35:02Speaker 01

  And I think particularly up at, up at the polls, people are at very high risk for that.

• 35:06Chris Williamson?

  Yeah, definitely. I mean, there's periods, entire months where the sun doesn't set.

• 35:11Speaker 01

  Yeah.

• 35:11Chris Williamson?

  If, if you were ever, if you were ever going to be somewhere and stuff with seasonal affective disorder, it's going to be, it's going to be either of the polls. So, um, going back to moods, um, have we, uh, is there any research which shows a link between someone with sleep, uh, uh, sleep deprivation and depression?

• 35:38Speaker 01

  That's an interesting question because actually historically sleep deprivation has been used as an antidepressant.

• 35:44Chris Williamson?

  Really?

• 35:45Speaker 01

  Yeah, a single night of sleep deprivation. So quite often it's the case that people with depression will experience poor sleep. And if you deprive somebody of sleep over one night, then they have this really strong increase in the pressure to sleep. And then in subsequent nights, they sometimes find it easier to get back onto some sort of consistent sleep schedule.

• 36:08Chris Williamson?

  Like wiping the edge of sketch board clean, so to speak.

• 36:11Speaker 01

  Kind of, yeah. But, but also during that night of sleep loss, people's mood does tend to improve acutely. And we don't really understand fully why that's so. I haven't looked closely at that research. I know that somebody who I've collaborated with, the University of Surrey has published some work on that. And they looked at the metabolome, which is where you basically take a biological sample. So let's say you take somebody's blood and you look at all of the metabolites that are in that blood sample at that particular time of day. And you can take them at various points during the day and look at how the metabolites respond to various interventions. So for example, diet or sleep loss.

• 36:52Speaker 01

  And if you look at the effects of sleep loss, then I think that there's evidence that you see changes in serotonin signaling, serotonin metabolites. And serotonin is a neuromodulator, neurotransmitter, which is important to things like mood.

• 37:08Speaker 01

  And sexual function, motivation, all sorts of things. But I think that the strongest evidence, of course, that serotonin is critical to that is the fact that what's the most common antidepressant medication people use?

• 37:23Chris Williamson?

  SSRIs, yeah.

• 37:26Speaker 01

  The uptake inhibitors, which basically prolong the amount of time that serotonin is in the synapse between neurons in the brain, it reduces the clearance of the serotonin from those. So, sleep deprivation does have the short-term antidepressant effects, but those effects aren't sustained over time. And actually, as I alluded to before, what you tend to see is that over the long term, of course, worse sleep is associated with poor and rude. And the tricky thing, as I briefly touched on, is just that often, somebody

• 38:05Speaker 01

  sleeps poorly, but how do you causally tie that to some specific outcome in an observational study? When people who sleep poorly might be smoking more, they might experience more stress at home, perhaps they drink, they have all of these other lifestyle behaviours that negatively affect the health outcome in question.

• 38:26Chris Williamson?

  Yeah, it's very difficult to isolate, right?

• 38:28Speaker 01

  Yeah, that's it.

• 38:29Chris Williamson?

  So, one thing that's interesting here, is there a way that sleep scientists have been able to detect the arrow of causality between sleep and issues, or issues and sleep?

• 38:44Chris Williamson?

  Am I sleeping badly because I'm depressed, or am I depressed because I'm sleeping badly, for instance?

• 38:50Speaker 01

  Yeah, I think it's easier to address the former question, because you can disrupt somebody's sleep and then look at that on an outcome. But you can't. Improve, for example, one particular outcome and then look at the effects of that on sleep. Does that make sense?

• 39:07Chris Williamson?

  Absolutely, yeah, absolutely.

• 39:09Speaker 01

  If you're looking at something like diet and sleep, then you can. You could do an intervention in which some people consume a specific meal three hours before sleep for a period of time and then cross them over into another group in which they consume a different meal and look at the effects of that on their sleep. It's just that if you have something like mood, then that's a much more difficult construct to try and get at.

• 39:34Chris Williamson?

  Incredibly subjective, right?

• 39:36Speaker 01

  Yeah, that's right.

• 39:37Chris Williamson?

  Very much so. So we've touched on sort of short and medium term effects of sleep. What about when we're talking over a lifetime for someone who potentially does shift work or has got chronic, is chronically underslept? What are the sort of things that can happen there? And then conversely, what are the effects of someone who's sleeping well over that period?

• 40:02Speaker 01

  Yeah, so over a lifetime, the best data that we have really are those types of observational data. And if you look, for example, at obesity, then people who report sleeping less than, I think, seven hours per night are at forty five percent higher odds of developing obesity later in their life. That's based on results from meta analysis, which is a study of studies which was published last year.

• 40:33Chris Williamson?

  That's over, that's seven hours, which I think for a lot of people would, they'd consider, oh, well, you know, I'm only one hour off eight and eight's what I'm supposed to get.

• 40:42Speaker 01

  Yeah, yeah, exactly. And of course, that could be misreporting, but when you're speaking about, in this instance, eleven studies on nearly two hundred thousand people, then that's actually quite persuasive.

• 40:55Chris Williamson?

  There's got to be some proof in the pudding, yeah.

• 40:57Speaker 01

  Yeah, I think so. But then there are also lots of other conditions that you could you could look at. So neurodegenerative neurodegenerative diseases like Alzheimer's or dementia. And again, you see that same type of association.

• 41:13Chris Williamson?

  Is there an increased risk?

• 41:15Speaker 01

  There is an increased risk with people who report poor sleep. Yeah, absolutely. And there are different ways in which we can think about poor sleep too. So in this conversation so far, we've mostly focused on sleep duration. But also there's of course, sleep efficiency. So let's say that you go to bed each night at ten P M and you wake up at six A M. You're in bed for eight hours. You're not going to be asleep the entire time. Sleep efficiency is the proportion of that sleep period in which you are actually asleep. So there's efficiency there. There's also sleep architecture, the way that you cycle through the different stage of sleep. There are specific sleep disorders, of course, of which there are over a hundred.

• 41:58Chris Williamson?

  Oh, wow.

• 41:59Speaker 01

  There's sleep timing and something that's gained more attention recently is sleep timing variability. So consistency in when people go to bed and wake up does seem to be important.

• 42:12Chris Williamson?

  Regardless regardless of duration and quality, just an upset in the regular cycle of the sleep times of sleeping and waking.

• 42:22Speaker 01

  Yeah, I think regardless of duration, I'm not sure that I would say regardless of quality. Because actually, when you go to sleep, it influences the quality of that sleep.

• 42:29Chris Williamson?

  Uh huh.

• 42:30Speaker 01

  That's related to the way that sleep is regulated. And I can I can just speak briefly about that if you'd like.

• 42:36Chris Williamson?

  I'd love you to speak deeply about it as I know that a lot of the guys who I work with. To give you a tiny little bit of background, my job as a club promoter means that

• 42:47Chris Williamson?

  if I I've tracked my sleep for around about thirteen hundred nights using the sleep cycle app on my phone. And if you were to look at the data, the variability that you have in my sleep and sleeping and waking time is almost twenty, it's almost global, it's almost twenty four hours. That very regularly throughout the week, I'll go to bed when I don't have work. Around about eleven o'clock or twelve o'clock and get up at sort of between anywhere between six and eight. But then when I go to work, I'll be working until three in the morning, I'll get home. Go to bed at four, wake up at ten or wake up at twelve and you know, this is. I'm only one person out of a massive, a massive nightlife industry, then add in shift workers and.

• 43:31Chris Williamson?

  You know, all manner of other people, there's a huge, a huge proportion of the population that this will affect, I'm gonna guess.

• 43:37Speaker 01

  Yeah, absolutely. And if you look at shift work, for instance, and that is a form of shift work, of course, then.

• 43:42Chris Williamson?

  Yeah.

• 43:43Speaker 01

  Roughly twenty percent of people in Europe and North America do shift work. And it doesn't just affect those people, it affects their loved ones too. So you have all these secondhand shift workers, you have to. Tolerate you poor shift workers who do that work and it's really important.

• 43:57Chris Williamson?

  You wake, you wake the missus up when you get in at four AM and then.

• 44:01Speaker 01

  That's right.

• 44:01Chris Williamson?

  Yeah.

• 44:02Speaker 01

  Yeah, so.

• 44:03Chris Williamson?

  What are the effects on, on shift work and what are the effects of variable sleeping and waking times on long, short and long term health?

• 44:10Speaker 01

  Yeah, so shift work, if you look at all the studies that have been done. And then compile those results, then it's associated with all sorts of negative outcomes, as you might imagine and.

• 44:20Chris Williamson?

  Well, give it, lay it, lay it to me frankly, doctor, tell me what it is.

• 44:26Speaker 01

  If, if you look at the strength of those associations, then it varies depending on the outcome, but. Shift work, night shift work specifically, is associated with things like. Obesity, diabetes, heart disease risk, stroke. Breast cancer has received some attention, certainly some cancers have stronger evidence than others. I think that. Whether it's associated with breast cancer has come into question recently, because there was a large report that was published that suggested that might not be the case. But almost everything does seem to be affected. The question is that. The question is, what is, what is it about shift work that predisposes people to that? Because it's a. Complex exposure scenario in which it's not just sleep that's disrupted or circadian rhythms that are disrupted.

• 45:10Speaker 01

  You also have people doing all of these things and of, often working stressful jobs, for example. That will also affect their risk of various diseases. So that's all, that's all important to understand. One thing, just to. Circle back to why, when you sleep affects the quality of your sleep.

• 45:32Speaker 01

  Is that if we look at how sleep is regulated, then there are two processes. And one of those processes influences how awake you feel at any given time. That's regulated by your circadian system. And what happens is that each day you wake up in the morning and then over the course of the day, you see this increase in the drive to stay awake. And then around the time that you normally fall asleep, there's a sudden drop in this wakefulness drive. The other process is the sleep process. And that's a process that builds with prolonged wakefulness. So the longer that you've been awake, the more sleepy that you are. And that's not a perfectly linear effect, but that's true to some degree.

• 46:16Speaker 01

  And there are various physiological correlates of that. And these are called somnogens. You can think of them as chemical barometers of how long you've been awake. So as I'm having this conversation with you, these are accumulating in our brains right now and they're increasing our pressure to fall asleep.

• 46:30Chris Williamson?

  Somnogens.

• 46:31Speaker 01

  Yeah, exactly. And if you look at shift work, then let's say that somebody does a slam shift. So they're used to being up during the week and then they have a single night shift. They get in at five AM and for the last five days, they've been waking up at six AM. What that means is that whereas at 10 PM the previous evening, they had this sudden drop in wakefulness drive and they were desperately trying to stay awake at the start of their night shift. Now, at this time of day at which they're trying to fall asleep, they're just starting to enter a period where the wakefulness drive is increasing.

• 47:09Chris Williamson?

  So is there a, there's sort of a lag with the, this sleepiness, the somnogens and the, the wakefulness drive. There's a lag behind what's actually going on. It's got like a, a delay on it for it to catch up.

• 47:22Speaker 01

  So there's this, there's now this big pressure to sleep because of the accumulation of these somnogens in the brain. But they've missed that opportunity to sleep. The time in which the wakefulness drive was very low. So they've got this combination of an increasing drive to be awake, but also very high sleep pressure. And for that reason, it's not, it's not quite as easy to fall asleep as it would have been otherwise. But let's say that they do fall asleep. What will happen is that as they enter sleep, the wakefulness drive is still increasing. And they're starting to pay off all of that sleep debt that they've accumulated. So as somebody falls asleep, all of those somnogens that are accumulating in the brain are then paid off back to normal levels.

• 48:06Speaker 01

  So over the course of a good night of sleep, what should happen is that the brain is restored. You wake up next day and you've got this big increase in alertness because you now have an increasing wakefulness drive and you've paid off all of the sleep debt. The problem is that now these people, they're going to sleep at six in the morning and they're starting to pay off all of that sleepiness from the previous day. But they've got this wakefulness drive which is kicking back in. So now they're experiencing an increasingly strong wake drive and less and less sleep pressure. What happens, they can't stay asleep. So maybe they get a couple of hours into their sleep episode and they just can't consolidate it.

• 48:48Chris Williamson?

  Yeah, I've certainly, I can certainly attest to that.

• 48:51Speaker 01

  Yeah, there's, there's sleep fragments and if you pull an all nighter and don't even try to go to sleep, let's say that you just, you go out and you're promoting your event. You get in and you just think, I'm not sleeping tonight. What you'll experience over the next day is that how sleepy you are doesn't just build predictably over the course of that day. It waxes and wanes.

• 49:10Chris Williamson?

  Yeah, it comes in waves.

• 49:11Speaker 01

  Yeah, and, and around lunchtime, we have this so-called post-lunch slump. And I think a lot of people historically have thought that that's the result of eating a big, heavy lunch. And that's not really the case.

• 49:22Chris Williamson?

  Is that, is, there's a, there's an argument that this is due to an evolutionary, um, biphasic sleep, um, tradition. Is that right? Or there's some people who've claimed that?

• 49:33Speaker 01

  Yeah, there are some people that have claimed that. And you do see that in certain groups of people who haven't been affected by the effects of industrialisation yet. So if you look at the Hadza hunter gatherers, for example, then what you see with them is that during the winter, they have monophasic sleep, so all of their sleep is consolidated in one nocturnal bout each night. But during the summer, they have a siesta.

• 50:00Chris Williamson?

  So the Spanish, the Spanish have got it right?

• 50:02Speaker 01

  Well, it's quite interesting in that Spain is a lot warmer than somewhere like the UK. And the Spanish have their siestas at lunchtime when it's hot. They get out of the sun and they take advantage of that post-lunch slump. And meanwhile, it's not quite so hot here and we carry on about our working days. So anyway, some people do seem to naturally have that pattern. I think if you're consistently in the habit of of sleeping in that way, then it's a perfectly healthy way to go. But also, what I would say is that if you're not used to that particular pattern, then during that lunchtime nap, you will see a reduction in the pressure to sleep as you fall asleep.

• 50:42Speaker 01

  And what that means is that when you then try to fall asleep that evening, you might have a harder time nodding off.

• 50:48Chris Williamson?

  Yeah, I could, I can definitely attest to that as well. So to give you some, um, this is, this is probably like patient zero for bad sleep for you, but I'll, I'll give you the, the example anyway. Very typically for me, if I've got a long day in the office, followed by a trip to Manchester from Newcastle to run one of our events, I'll wake up at maybe, I'll try and push my waking time a little bit further back. So I'll wake up at nine, I'll work and then I have to drive back from Manchester to Newcastle. I'll go to bed at six AM and then looking at my clock, I'll think to myself, 24 hours from now, I'm going to want to be getting up because it'll be a Monday and I'll want to start my week on a good note. But that means that at six AM on Sunday morning, I need to fall asleep, wake up,

• 51:31Chris Williamson?

  fall asleep and wake up in the space of 24 hours. And, you know, as much as.

• 51:39Chris Williamson?

  Like getting up and getting after it can be viewed as an admirable quality in a 21st century corporate society where, you know, everyone's trying to be successful. It doesn't sound like that's the best thing for for my health.

• 51:54Speaker 01

  No, it probably isn't. But it's unavoidable in that particular scenario. So the question is what do you do to cope with that sleep loss? And I think that what you try to focus on is getting some sleep and coping with the sleep loss during the way, but doing so in such a way that you don't interfere with your ability to fall asleep the following evening. And another thing to consider is that you can try and preemptively prepare for those episodes by banking sleep beforehand. So banking is an apt analogy here in that, let's say that you're trying to accumulate a certain amount of wealth in the coming week, and each minute of sleep that you get represents one one pound. Okay?

• 52:39Speaker 01

  This week, you try to to bank as many pounds as possible by getting as many minutes of sleep as possible, knowing that next week, you're not going to get that much sleep. And subsequently, next week, you're going to be in debt. So that's how you try to prepare for it. So with you, Chris, let's say that you've got a really good week this week, and you can you can try to be consistent in your patterns, knowing that next week, you've got several events. That will help protect you in certain ways against the negative effects of the sleep loss that you will experience next week.

• 53:11Chris Williamson?

  That's crazy. So it is. It is literally like a savings account.

• 53:16Speaker 01

  Well, it is if you have a history of incomplete sleep. So let's just say that there's a fairy tale scenario in which somebody's always slept perfectly.

• 53:26Chris Williamson?

  Yeah.

• 53:27Speaker 01

  That person couldn't necessarily bank sleep, because they don't have any sleep debt from their previous life.

• 53:33Chris Williamson?

  Yeah.

• 53:34Speaker 01

  However, that person doesn't exist, as far as far as I can tell, at least. And for that reason, we probably all have something of a sleep debt to pay off. And banking, although it might not be the case that it's technically possible, it is effective nonetheless in terms of what we're trying to achieve.

• 53:56Chris Williamson?

  So you could, would you aim to push maybe an extra half an hour or an extra hour for the couple of days preceding a late night?

• 54:05Speaker 01

  Yeah, I'd go about it in a few different ways. And I think the one thing that's important to recognise is that trying to force yourself to just go to bed earlier might be a fool's errand. The reason is that the wake drive that I mentioned before is at its highest just before you try to fall asleep. And some sleep researchers refer to that as the forbidden zone for sleep. You just have a really hard time falling asleep at that particular time.

• 54:31Chris Williamson?

  That's lying awake staring at the ceiling, right?

• 54:34Speaker 01

  That's exactly right, yeah. So what you would do then is potentially try to shift your body's internal clock, your circadian system, a bit earlier. And you'd do that by exposing yourself to lots and lots of bright light early in the day, perhaps doing some exercise early in the day too, and then trying to reduce your nighttime light exposure and starting your sleep routine a little bit earlier. Okay, so that's that's one way of intervening. Another thing is to address your caffeine intake. So while you're trying to bank sleep, trying to taper that or maybe go cold turkey and.

• 55:08Chris Williamson?

  Oh, don't do it to me, Greg, please.

• 55:12Speaker 01

  But it does make sense because.

• 55:14Chris Williamson?

  I know, but you're killing me.

• 55:17Speaker 01

  Caffeine is an adenosine receptor antagonist. So one of the somnogens, which we spoke about earlier, is adenosine, which is a breakdown product of ATP. So as your brain expends energy during the day, it releases ATP from prefrontal neurons into the extracellular fluid that bathes brain cells.

• 55:36Chris Williamson?

  Okay.

• 55:36Speaker 01

  And this ATP can act directly on sleep circuits in the brain to promote sleep. It can disinhibit, sorry, can inhibit wake promoting circuits too. Or the ATP can be broken down to adenosine and that can also have similar effects. And anyway, caffeine blocks the interaction of that adenosine with its receptors.

• 55:58Chris Williamson?

  It binds to the same receptor, right?

• 56:00Speaker 01

  So basically, you've got all of this, that's exactly what it does. So you've got all this sleep in a signal, but it's like somebody shouting and there are no ears there to hear the person shouting.

• 56:10Chris Williamson?

  Okay. So avoid, avoid, avoid caffeine for those couple of days. Try and get yourself, try and get yourself up and get moving. So you, you're almost artificially, um, you're artificially moving the daylight a little bit earlier in the day and then closing the sunset off a little bit earlier as well.

• 56:28Speaker 01

  Yeah. And then try and avoid waking to alarm if possible during that time. And you can also use banks to try to, sorry. You can also try to use naps to bank sleep during the day. If you're, if you're very short on sleep during that time when you're trying to bank sleep. And using a nap during the post lunch lamp can be useful.

• 56:48Chris Williamson?

  Okay. Well, that's a, that's a, that's a really cool, a really cool little bit of advice there. So I want to, we've, we've touched on the effects of sleep and, and how important it is. I want to talk about enhancing your circadian system function uh, and sleep. And then also how we can cope with, with sleep loss. And then we're going to finish on, uh, finish on some stuff to do with human OS. So if you were to write a prescription for someone who wanted to have as good sleep as they could, have you got some principles that they should be sticking to?

• 57:20Speaker 01

  Yeah, many principles. And I think that it's worth starting with the daytime. So during the day, you want to be physically active. And the reason that she comes back to adenosine and the fact that as you burn more energy, you accumulate more adenosine. And, and then that helps you sleep more deeply at night. During the day, you also want to expose yourself to lots of bright light. And because the amount of energy that your brain burns, you want to do cognitively demanding work. And also that can include other activities. So things like meditation are actually quite taxing and do consistently improve sleep, not just because of that effect, but also because they probably have roles on things like stress regulation.

• 58:05Chris Williamson?

  Parasympathetic nervous system and stuff like that, right?

• 58:08Speaker 01

  That's right. Yeah. And then during the night time, I think that it's valuable for somebody who's not in a very consistent pattern to set an alarm in anticipation of their bedtime. So let's say that your sleep routine takes you an hour, then you would set your alarm for an hour before bedtime.

• 58:26Chris Williamson?

  Yep.

• 58:27Speaker 01

  Regarding your bedroom itself, you want to make it stress free. So keep it uncluttered. And use it for sleep and sex only. And then light exposure is really, really important. So during the day, get outside lots and lots of bright lights. And then probably around two hours before you intend to go to bed. You want to start reducing your light exposure. And where possible, I would avoid artificial lighting, but I know that that's often not possible. So what can you do in those circumstances? You can use apps on your devices, so things like Twilight for Android systems or Night Shift Mode for iPhones. You can use F dot Lux on your laptop, which is on mine right now.

• 59:12Speaker 01

  You can also use things like blue blocking glasses. I don't personally use them, I just don't have the self-confidence.

• 59:17Chris Williamson?

  We're getting into Ben Greenfield territory with blue blocking glasses, aren't we?

• 59:21Speaker 01

  Yeah, a little bit.

• 59:25Speaker 01

  So there's that too. And then as you fall asleep, are these blackout blinds in your bedroom? Good curtains or just use a sleep mask?

• 59:35Chris Williamson?

  Is there a, is, is there any substance to photoreceptors in your skin being able to detect light?

• 59:43Speaker 01

  In short, I, I don't think so. There was a paper that was published in the Journal of Science in nineteen ninety seven, which received a lot of airtime. This was the kind of journal article that would get on the front page of the Washington Post because it was novel. But it wasn't replicated. And what they did is they shone light on the back of somebody's knee, I think. And, and supposedly it was able to shift the timing of the circadian system. And it hasn't been shown since. So as far as I'm aware, that's not the case. I know that there are these devices now that do things like shine bright lights in your ears.

• 1:00:23Chris Williamson?

  Yeah, there's all, all kind of weird and wonderful uh sleep aids now, isn't there?

• 1:00:29Speaker 01

  Yeah, and, and not just for sleep because light actually has a variety of.

• 1:00:35Speaker 01

  Other effects, the non-image forming effects, but effects that are either relates to the circadian system, or they have effects on things like cognition. So bright light exposure during the daytime routinely will acutely boost someone's mental performance if they haven't been exposed to bright light before that. And that's why actually one of the ways to cope with sleep loss that we come to is making sure that you spend some time outside. So that is part of the picture. But these devices anyway, that shine-

• 1:01:06Chris Williamson?

  That are shining lights in your ears?

• 1:01:08Speaker 01

  Yeah, I'm, I'm, I'm not sure about them. I haven't looked closely at the research.

• 1:01:11Chris Williamson?

  You don't have a pair?

• 1:01:13Speaker 01

  I don't have a pair, no. And I, I'm not aware of any sleep researchers that seem particularly persuaded by their utility, I'll put it that way.

• 1:01:27Chris Williamson?

  Okay, so I mean, there's, there's definitely a, going back to a couple of Ben Greenfield podcasts that I've heard and a few other anecdotal bits of evidence, people that go into hotel rooms and will put tape over microwave and air conditioning LEDs and stuff like that, because even if they've got a, they've got their sleep mask with them, they're not happy with the darkness of the room.

• 1:01:48Speaker 01

  Yeah, I, I, I think that a lot of that is overkill.

• 1:01:51Chris Williamson?

  Is that sweating the small stuff?

• 1:01:53Speaker 01

  It's, it's sweating the small stuff. And the point actually is that these photoreceptors in your eye that are involved in the regulation of the circadian system are quite sluggish. They, they keep a track record of your light exposure over the course of the day. They don't respond very acutely to it. So if you spend lots of time outside during the daytime, had lots of bright light exposure, which is of a blue wavelength in particular, then a little bit of light exposure at night from a microwave is a drop in the ocean.

• 1:02:27Chris Williamson?

  Yeah.

• 1:02:27Speaker 01

  It just won't shift your system. With that said, if you'd been in complete darkness for the previous 16 hours, and then you went to the toilet and you switched the light on when you went to the toilet, then that actually probably would shift the phase of your circadian system.

• 1:02:41Chris Williamson?

  That's interesting. So you kind of become, your sensitivity to light is increased based on what the, the most recent period of your day has been like?

• 1:02:49Speaker 01

  Strongly so, yeah.

• 1:02:50Chris Williamson?

  That's crazy. That's, I guess for people in certain professions, that's going to be a, a very important fact for them to take away.

• 1:03:00Speaker 01

  Yeah, it has, it has strong implications for, for shift work and for things like jet lag too, because you have situations in which you want to go to shift work, for instance, but you, you're just there for one evening.

• 1:03:15Chris Williamson?

  Uh huh.

• 1:03:15Speaker 01

  You to adapt to.

• 1:03:17Chris Williamson?

  Well, did you, you, you referred that, referred to that as a slam shift?

• 1:03:20Speaker 01

  Yeah, yeah, and you've got all these different shift work schedules. And in some instances, particularly in remote environments, people will want to go somewhere and they will always be on night shifts. And in those rare circumstances, you want to fully adapt your circadian system. And all you do then is you manipulate your environment such that you make that as easy as possible and you don't go outside. That's, that's, that's not most people.

• 1:03:48Chris Williamson?

  Yeah.

• 1:03:48Speaker 01

  So the question in those situations is how do you go to work, maintain vigilance during that time, but not screw yourself up too much in the long term, in the days to come?

• 1:04:00Chris Williamson?

  With, with difficulty, it sounds. So we've got, uh, we've got the blackout lines. We've tried to expose ourselves to light during the day. Um, we've had our, I guess what you would, what's commonly referred to as a digital sunset, that two hour period before you're going to sleep, starting to reduce your light exposure, specifically to blue light, which is what's emitted from things like phones and iPads and TVs and laptops and stuff like that. If you do have to use them, use a Hueing program, which is night mode on, on an iPhone or a similar, similar application elsewhere. Um, what about sleep posture and sleep temperature and the sleep environment that you're actually laid on? Did you, have you looked into this much?

• 1:04:41Speaker 01

  Yeah, I've looked at temperature. Posture's interesting and I, it's funny, actually, I'm, I'm interviewing a guy for our podcast, Stuart McGill, who's arguably the world's foremost expert in spine biomechanics in a few days' time. And I'm curious to hear his thoughts on that. I think that the best sleeping posture is likely highly dependent on the person.

• 1:05:05Chris Williamson?

  Probably the most, probably the most comfortable one, right?

• 1:05:08Speaker 01

  Surprise, surprise.

• 1:05:11Speaker 01

  So but anyway, some people's spines are very flexion intolerant. If they bend over to tie their shoes or whatever, if they sit at a desk all day, then their spines really don't like being in that position. So sleeping on their back over time might not be wise. Other people are really extension intolerant. So if they arch back and look up at the ceiling, then they experience pain. That's a pattern you see in people like gymnasts. And for those people, sleeping on the front is going to be unwise. I think for most people, sleeping on the side is probably smart. And I generally find that people often benefit from having a pillow between their knees during sleep too. Something between their knees, just to keep them slightly ajar. And I suspect that's related to the spine, but I don't actually know what the mechanism is.

• 1:05:56Speaker 01

  It's just that many people seem to be more comfortable in that position.

• 1:06:00Chris Williamson?

  But you and Mr McGill will hopefully find that out. By the time that we've published this, I think yours will be up as well. So I'll make sure that I'll link that in the show notes for the listeners who want to go and do some further reading or further, further listening it should be. So how about temperature?

• 1:06:13Speaker 01

  Yeah, so temperature is interesting in that what we want to do is raise the temperature of the skin by a couple of degrees shortly before sleep. And this is counterintuitive because during sleep, the temperature of your brain drops as you progress into deeper, late stages of sleep. So during deep sleep, it's at its lowest. And then during REM sleep, as the metabolic activity in your brain rises, it goes up again.

• 1:06:41Chris Williamson?

  Is that just as a, is that as a byproduct of the activity or is that?

• 1:06:46Speaker 01

  Yeah, it is. It is partly a byproduct of the activity, but things that you can do to facilitate that drop.

• 1:06:52Chris Williamson?

  Yeah.

• 1:06:53Speaker 01

  So help you fall asleep. And by raising the temperature of your skin, you create this gradient between your core temperature deep within you and the temperature of your brain and the temperature of your skin. And that helps you radiate heat out from your core, improving your ability to drop the temperature of your core and your brain. So a simple way to achieve that is a hot shower. Typically about 10 minutes at about 40 degrees C is about right, within maybe an hour of when you go to bed. And then the, the parts of your body are also relevant too, because your hands and your feet and probably your ears too are.

• 1:07:34Speaker 01

  Relatively unique in their structure. They have a very big surface area, but not such a big volume, and that makes them very effective at transferring heat to the environment.

• 1:07:43Chris Williamson?

  The body's radiators, right?

• 1:07:46Speaker 01

  Yeah, exactly. So when you get out of the shower, you want to keep your feet warm. So stick some socks on and that seems to consistently help people both fall asleep faster, stay asleep and perhaps sleep a little bit longer too. There's been some research published on that in the last few months.

• 1:08:06Chris Williamson?

  By keeping their socks on?

• 1:08:09Speaker 01

  Yeah, well, in that instance, it was actually using these special socks that would warm the feet slightly during sleep.

• 1:08:15Chris Williamson?

  Okay, so all of the girlfriends that are listening, who absolutely hate their boyfriends going to sleep in socks, they're actually, they actually need to sideline their concerns about fashion and focus more on the fact that they're potentially getting a little bit better sleep.

• 1:08:34Speaker 01

  They need to stick their sleep masks on.

• 1:08:36Chris Williamson?

  Yes, and then they can't see the socks. Yes, we've found the solution. So you've had the hot shower before you go to bed and that is going to help you radiate heat away, right from your core?

• 1:08:48Speaker 01

  Yeah, but then, of course, you don't want the surrounding temperature to be too high and you want your bedding to let you continue to lose heat. So it needs to be able to effectively transfer heat. And I know there are some companies out there that say that their sheets are better than other sheets that are doing this. I'll just look into them. There are a couple of companies I'm familiar with. One of them is called Sheeks.

• 1:09:15Chris Williamson?

  It's a good name for a sheets company.

• 1:09:18Speaker 01

  Absolutely. And you can look into those. But anyway, the point is that you don't want your bedroom to be too warm. You also don't want it to be very cold because, again, thinking about evolution, if the environmental temperature was very hot or very cold, then that's a stress to the body and it's a signal that you don't want to hang around because otherwise you're going to disrupt your ability to regulate your internal environment. And for that reason. Bedroom needs to be comfortable but cool.

• 1:09:51Chris Williamson?

  So you would err on the side of cooler than warmer.

• 1:09:54Speaker 01

  I would, yeah. And actually, one thing that I I love is using a fan. Because it it serves two purposes. It it keeps you cool. I would aim at your torso. And also, it's a form of white noise. So if you're in a relatively busy place and it just drowns out all of the extraneous disturbances that could otherwise wake you up from sleep.

• 1:10:17Chris Williamson?

  Well, I'm glad that you've actually hit upon one habit that I've had for about seven years, which is a tiny little steel desk fan. Which is next to my bed and I've kept kept with me since uni. Um, and yeah, that's I I couldn't attest to that more. It's nice to have the breeze and also you totally right about the white noise in the background. Especially if my sleep pattern's been thrown out a little bit and I'm trying to then sleep through a morning where I've got housemates that might be moving around and. Cars going up and down outside. Yeah, it's a definitely a double whammy on that front.

• 1:10:48Speaker 01

  Yeah.

• 1:10:49Chris Williamson?

  Um, so what else can we do to enhance our sleep or our circadian system function?

• 1:10:55Speaker 01

  Okay, so just sticking with sleep, a couple more things. One is related to diet. So. Spoke about caffeine briefly earlier. I would just say.

• 1:11:05Speaker 01

  Caffeine typically is metabolized relatively slowly. And for that reason, you don't want to consume it too late in your day as an arbitrary cutoff. I would say try to not consume caffeine any later than about nine hours before you plan to fall asleep.

• 1:11:20Chris Williamson?

  Oh, wow. That is that is potentially very early for a lot of people, isn't it?

• 1:11:25Speaker 01

  Well, it's it's it's going to be hard for for shift workers in particular.

• 1:11:29Chris Williamson?

  Yeah.

• 1:11:29Speaker 01

  But I I think also that caffeine is something that when you go through the initial period. Of cutting your caffeine intake, it sucks. Many people have.

• 1:11:39Speaker 01

  But it passes.

• 1:11:40Chris Williamson?

  Yeah.

• 1:11:40Speaker 01

  And over time, as your sleep quality improves.

• 1:11:45Speaker 01

  The nice thing also is that you become more sensitive to caffeine again.

• 1:11:48Chris Williamson?

  Yeah, so you need less. So you net a benefit on a number of different fronts.

• 1:11:52Speaker 01

  Yeah, exactly. And then when you do use it for those night shifts infrequently, it has a very strong alerting effect on you. So you improve your sleep, you feel terrible for a couple of days. When you're over the ham, it's all good. So anyway, I would say no more than about two milligrams of caffeine per kilogram of body mass. So if you're eighty kilos, then that's a bit more than a coffee. I know that's an awful lot, but eat that by nine hours before bed.

• 1:12:24Chris Williamson?

  The half, the half-life is, is, it tails off very slowly, doesn't it?

• 1:12:27Speaker 01

  Half-life's about six hours. Yeah. And the half for listeners is, is just the amount of time that it takes for the caffeine concentration in your bloodstream to reach half of the peak value of the experience after consuming caffeine. So another thing is alcohol. And a lot of people use alcohol as a sedative. And alcohol does reduce the amount of time that it takes people to fall asleep. It increases the amount of deep sleep that people get early in the night. But then later in the evening, as your liver clears the alcohol, your body tries to frenetically try and catch up on the lost rapid eye movement sleep. And what tends to happen is you have these bizarre dreams and your sleep also fragments. So the quality of your sleep is reduced.

• 1:13:11Chris Williamson?

  I think this is um something from, that I'd read with Matthew Walker's book, which is the important distinction between sleep and sedation when using substances to assist you. I think the same came up with regards to marijuana.

• 1:13:26Speaker 01

  Yeah, that's right. And many sleep drugs are hypnotics. So they, they, they put you in a more suggestive state. And, and you can, you can fall asleep more easily from that. But they don't necessarily produce physiological sleep.

• 1:13:43Chris Williamson?

  It's time under the, time under the curve that you're after, right? Not just the planting the flag in the ground of I am no longer awake.

• 1:13:51Speaker 01

  Yeah, yeah, and it it's a it's a real issue. And actually, for people who struggle with sleep, one thing that I will say is that if you have insomnia, the first port of call is always CBT, cognitive behavioural therapy for insomnia. If you're in the UK and you have insomnia, then I think that the NHS will subsidise an online CBT programme. And what it is, is asleep education modules, teaching about sleep hygiene. It's very effective, very, very effective. And it's as effective online as it is in person, too. So go that route before you touch any of the sleep drugs. I think sleep drugs occasionally have their place. So let's say that, Chris, you fly out to Hawaii.

• 1:14:35Chris Williamson?

  Yep.

• 1:14:36Speaker 01

  And you're there for two days. And by the time you go to bed that evening, it's the time at which you'd normally wake up back at home. And there's no way that you're going to fall asleep.

• 1:14:47Chris Williamson?

  Yeah.

• 1:14:48Speaker 01

  In that instance, I personally wouldn't mind taking a small amount of one of the over the counter sleep aids that you can take.

• 1:14:58Chris Williamson?

  Do you have a, do you have a list of ones that are, um, Dr Greg Potter approved?

• 1:15:04Speaker 01

  I'm not going there.

• 1:15:05Chris Williamson?

  Do you, do you have a list of ones which you use? Or would use?

• 1:15:10Speaker 01

  Well, this, this isn't advice.

• 1:15:13Chris Williamson?

  This is not advice. Okay. To be incredibly clear to everyone who's listening, this is a hypothetical situation.

• 1:15:19Speaker 01

  This is not advice. And it's so probably actually not what I would take if I had access to sleep drugs, because many of them are only available under subscription.

• 1:15:28Chris Williamson?

  Okay.

• 1:15:28Speaker 01

  Prescription, sorry.

• 1:15:29Chris Williamson?

  Yeah.

• 1:15:30Speaker 01

  So you can get diphenhydramine over the counter, which is just the stuff that's in nitol. And that is what's called an inverse agonist that histamine H1 receptors in the brain. It just means that instead of just blocking the interaction of histamine with its receptors, histamine is a wake promoting neuromodulator. And instead of just blocking that interaction, it actually has the opposing effect. And diphenhydramine seems to help people fall asleep a little bit faster and stay asleep slightly longer. And it is available over the counter. The recommended dose is 50mg in the research. You normally buy it in 25mg tablets and they'll say, start with that.

• 1:16:10Chris Williamson?

  Yeah.

• 1:16:10Speaker 01

  And increase your dose up to a maximum of 50mg. So I think that can be useful. The problem with all of these things is that when you target one particular

• 1:16:20Speaker 01

  Neuromodulator in that way, you can quickly produce dependence and withdraw.

• 1:16:25Chris Williamson?

  Yeah.

• 1:16:26Speaker 01

  Actually, it's funny because there's a discordance between people's perceptions of natural substances and medications. So people will often resort to herbal sleep aids, thinking, oh, it's natural, it must be safe. If they're targeting the same chemical pathways in the brain, then just because something is from a plant, it doesn't mean that it's magically going to be okay and that it's it's going to have fewer negative consequences than its synthetic counterpart.

• 1:17:00Chris Williamson?

  The potential for it to carry along with it some byproducts that might have unintended consequences as well is probably a little bit higher than something that's been synthesized purely for the purpose of being that that particular pure compound.

• 1:17:11Speaker 01

  How how well regulated is the supplement industry?

• 1:17:14Chris Williamson?

  Incredibly not. But the drug industry is also, well, debatably, but at least a little bit more, I think.

• 1:17:23Speaker 01

  Yeah.

• 1:17:24Chris Williamson?

  So what about, and I'm going to touch on it because I was recently in America, and this is, this seemed so widespread. I knew that I was going to have a sit down with you, so I wanted to ask some people. Of a group of five men and 10 women that I was sat around a table with, which is definitely not a representative sample, but 10 out of the 15 of them all use melatonin every night and all of them reported using the tablets at least a couple of times per year.

• 1:17:55Speaker 01

  Okay.

• 1:17:56Chris Williamson?

  The tablets that they were referring to mostly were sublingual ones, which dissolve under the tongue. I know that melatonin isn't available in the UK, so this may be a supplement that a lot of people who are listening have never tried. Have you had a look at much research to do with melatonin? I guess it's external melatonin or?

• 1:18:17Speaker 01

  Yeah, I have. Well, the final chapter of PhD was was on this topic.

• 1:18:21Chris Williamson?

  Oh, well, you you should you should know a little bit about it then.

• 1:18:25Speaker 01

  Yeah, I wouldn't claim that. But but anyway, that's that's interesting. And what you're saying is that those people take it when they're at home on local time, but they think that it helps their sleep.

• 1:18:36Chris Williamson?

  Exactly that. And multiple multiples of this group were combining that with wine, and of that, a smaller subsection were combining it with wine and weed.

• 1:18:46Speaker 01

  Yeah, so so polypharmacy isn't smart.

• 1:18:52Speaker 01

  And and I I don't recall the specific interactions for melatonin. I think that it competes with caffeine. So so anyway. Melatonin is metabolized by the liver by some cytochrome enzymes, I think P four fifty. And there are various other xenobiotics, so just foreign compounds, chemicals that are metabolized by that same enzyme. And what that means is that if you take it at the same time something else, then often the melatonin ends up being broken down far less efficiently than it would be way to take it by itself.

• 1:19:27Chris Williamson?

  So you definitely shouldn't be drinking and melatonining.

• 1:19:31Speaker 01

  It it's just a weird combination, too.

• 1:19:34Chris Williamson?

  Well, being being being frank, you know, uh if that's the worst thing that the people sat around the table were taking from America. It's it's potentially not, it's certainly not as bad as some of the some of the stories that you hear coming out. But so what? It could be an awful lot worse, yeah.

• 1:19:53Speaker 01

  Back to melatonin as a sleep aid.

• 1:19:55Chris Williamson?

  Yes.

• 1:19:56Speaker 01

  I I think that it's useful for helping people to synchronize their circadian systems when the circadian system is misaligned. So jet lag or adaptations to chronic shift work, great, perfect use case scenario. With very old people, sometimes they experience things like calcification of the pineal gland. And in general, their circadian rhythms become more disruptive, more disrupted at many levels.

• 1:20:29Chris Williamson?

  Are we talking sixty plus, seventy plus?

• 1:20:33Speaker 01

  It's it's like anything else. If you look at the loss of skeletal muscle mass with age or decline in cardio respiratory fitness, it's it's a gradual process.

• 1:20:41Chris Williamson?

  Okay.

• 1:20:41Speaker 01

  It's it's not like there's some sharp cutoff, but they probably could be with some disease states, but that said.

• 1:20:46Chris Williamson?

  Okay.

• 1:20:47Speaker 01

  As as you see these dampening of circadian rhythms with age, I think that those people would sometimes benefit from melatonin. And there's a little bit of evidence to that end, too. So, for example, there's been work on people with insomnia.

• 1:21:05Speaker 01

  Who are also elderly, taking a slow release form of melatonin called circaden at two milligrams, and it seems to help those people maintain their sleep over the course of the evening. There's also some work on post-menopausal women and the effects of taking melatonin over the course of a year, looking at bone mineral density in particular and body composition. And actually, melatonin seemed to increase bone mineral density and reduce fat mass. So at the end of the year, their weight was relatively stable, but the composition of that weight had improved.

• 1:21:37Chris Williamson?

  Ah, yeah, okay.

• 1:21:38Speaker 01

  So with those elderly people, I think that it can be useful. But but for most of us who have relatively well functioning circadian systems, I don't see it as being very useful. I I personally would use it at a five milligram dose during jet lag. Jet lag being when you travel from across at least three time zones.

• 1:22:02Chris Williamson?

  Uh huh.

• 1:22:03Speaker 01

  And I would take it about two hours before bed typically. And you can use it preemptively too. So if you want to help you start preparing to adjust to a different time zone in advance of flying out there, then you can take it in the days before. So let's say that you want to fly three time zones to the east and you'll need to wake up earlier and go to bed earlier.

• 1:22:26Chris Williamson?

  Yeah.

• 1:22:26Speaker 01

  You can start taking melatonin progressively earlier in the days before.

• 1:22:30Chris Williamson?

  Yeah, start to start to align yourself with the time zone that you're moving to before you get there.

• 1:22:34Speaker 01

  Yeah, so I think I think that's useful.

• 1:22:37Chris Williamson?

  Okay, and then shift shift work potentially as well?

• 1:22:41Speaker 01

  Chronic shift work, yes, to to to help stabilize their patterns, because it's just so easy for people that consistently work night shifts to finish up and then start driving home and, ah, the sun's coming up, and it's coming up at exactly the wrong time.

• 1:22:56Chris Williamson?

  Yeah, yeah. It's regular when I'm driving back from Manchester, if it's during the summer, that I'll need to put my sunglasses on because I'm driving down and the sun's setting. And then around about three thirty or four AM, I'll need to put my sunglasses back on because the sunrise is hitting me in the face as I'm trying to get home.

• 1:23:14Speaker 01

  Yeah, well, it's smart. That's exactly what you should be doing, putting your sunglasses on.

• 1:23:17Chris Williamson?

  Yeah.

• 1:23:17Speaker 01

  While making sure that you stay awake and of course, you shouldn't be driving drowsy.

• 1:23:23Chris Williamson?

  I'm not, I'm, yeah, but I also can't have, you've told me that I can't have caffeine up to, ideally up to nine hours before bed and the half life, six hours. But my usual plan of necking a monster three hours before I get home, which is the exact time that the journey takes me, is um, I'm kind of fighting, it's an immovable object and an unstoppable force here, isn't it?

• 1:23:45Speaker 01

  Well, what I'll add is before we just return to melatonin, you can take a very brief nap. And actually to have the biggest short term effect on your alertness, all you need is a 10 minute nap.

• 1:23:59Speaker 01

  If you take a longer nap, then you start to progress into deeper stages of sleep. And the issue with that is that as you go into deep sleep, you have this sleep inertia afterwards. So you wake up and you feel drowsy.

• 1:24:09Chris Williamson?

  Yeah.

• 1:24:10Speaker 01

  You have this later boost in alertness, which is actually ultimately of a greater magnitude than the short, the shorter nap. But if you just want a, a brief nap and something that's going to give you the kind of increase in alertness that you get from the caffeine, 10 minutes by the side of the road, if you stop off, will give you much the same effect and it won't impair your ability to fall asleep later either.

• 1:24:31Chris Williamson?

  That's, that's fantastic. So I'll, I know that my business partner Darren will be listening. He, he absolutely loves, I think, whether it be services or Scotch Corner are his two favourite spots on the A1. Um, so, you know, he's got it right by, I think he takes one of his socks off and drapes it across his eyes if it's too bright outside. I'm not sure how, how scientifically accurate using a sock for a face mask is, but it's a,

• 1:24:57Chris Williamson?

  needs must, I suppose. So going back to the melatonin use, do you think then that a lot of the dependence on this is just that, that it's a psychological dependence rather than a physiological one?

• 1:25:10Speaker 01

  Well, there's lots of interesting pre-clinical, by which I mean studies on animals, research that's been done, showing all of these positive effects of melatonin on various outcomes. There's actually a journal called the Journal of Panial Research, and everything in that journal, more or less, is about melatonin. And melatonin does all sorts of cruel things to other animals. You give them a fattening diet, melatonin reduces the fattening effects of that diet. You induce diabetes temporarily, melatonin protects against the development of diabetes or helps reverse it. So with that in mind, I think a lot of people have looked at some of this early research and thought, oh, well, melatonin seems innocuous.

• 1:25:55Chris Williamson?

  They think it's a panacea.

• 1:25:56Speaker 01

  Yeah, but I suppose what I will say is that it is remarkably safe, melatonin. And whereas the other sleep aids that people take will lead to that kind of tolerance and withdrawal effects that I mentioned, melatonin's unusual because it doesn't really seem to have that effect. So if you, for example, as a guy, take testosterone, then there's this negative feedback cycle. You have this exogenous or from outside the body testosterone that's floating around your bloodstream, and your body will naturally shut down its own production to help you maintain relatively normal levels within your bloodstream. But with melatonin, that's not really the case. If you take melatonin from the outside, and actually a common melatonin dose, let's say

• 1:26:38Speaker 01

  two milligrams, that will produce melatonin levels in your blood, which is orders of magnitude higher than the natural levels that you would produce. And actually, there are some people who have absolutely no detectable melatonin in their blood during the day at any time, and they sleep okay. So melatonin, whereas people think about it as a sleep hormone, isn't really a sleep hormone. If you take in this big doses, then it does reduce core body temperature and help people fall asleep a little bit faster, and you do sometimes see that effect in healthy people. But apart from that, the effects on sleep seem to be quite negligible. And there's also some emerging evidence now that melatonin does play roles in metabolism

• 1:27:21Speaker 01

  as you would expect because it's carrying this nighttime signal throughout the body. And in people with a particular variance of the melatonin receptor, having too much melatonin floating around at the wrong times is not a good thing because, for example, it will impair their ability to dispose of glucose in their bloodstreams effectively.

• 1:27:40Chris Williamson?

  Yeah.

• 1:27:41Speaker 01

  So with all of that said, healthy young person taking melatonin, they might fall asleep a little bit faster, they're unlikely to do themselves any harm in the long term. If they have this melatonin receptor variant, then it might be contraindicated. But save your money and spend it on something more fun or more valuable to your health.

• 1:28:01Chris Williamson?

  Yeah, so save the money on that tub of melatonin or something similar and buy a pair of blackout blinds.

• 1:28:08Speaker 01

  Much smarter.

• 1:28:09Chris Williamson?

  Okay, just because we're on to draw a line under substances, compounds like 5-HTP, I know that they're very, very popular. Have you had a look at anything to do with that?

• 1:28:22Speaker 01

  I have, yeah, but not, not this year, actually. I did until about December last year have a relatively close look at the literature on all sleep supplements. So some of the herbs that are out there, various amino acids, so 5-HTP, tryptophan, glycine, there are all sorts of ones that people have looked at.

• 1:28:44Chris Williamson?

  What does the research say about them?

• 1:28:50Speaker 01

  Tryptophan might be the most interesting to me, other than glycine, we'll come back to glycine. So tryptophan, there was a lot of research on in the 1980s or so. And it's a precursor to melatonin ultimately, but via serotonin.

• 1:29:08Chris Williamson?

  Okay.

• 1:29:09Speaker 01

  And it's funny because people once thought that serotonin was a Sleep hormone, and it's not, it's actually the exact opposite. It it depends on the part of the brain that you're looking at, but in general.

• 1:29:20Chris Williamson?

  Wakefulness hormone.

• 1:29:21Speaker 01

  Yeah, serotonin is involved in wakefulness. So taking tryptophan with a view towards increasing melatonin levels. Doesn't make that much sense if it needs to go via serotonin. But anyway, some of those early research studies on tryptophan did show some effects on sleep. I don't recall the specifics off the top of my head, but I think people might have fallen asleep slightly faster. And they they were, there were some well done studies to people using polysomnography, which is where you measure things like the electrical activity in someone's brain and their eye movements. And that gives you the most objective measure of different sleep stages that people cycle through.

• 1:30:00Chris Williamson?

  Yeah.

• 1:30:01Speaker 01

  So tryptophan is interesting, but there hasn't been the kind of rigor in the research that I would want to see before I would recommend it. Glycine is interesting for various reasons, not just related to sleep. And I I think that glycine is relatively benign, it's one of these things that you can take and it's unlikely to hurt you. Glycine might help with sleep by binding to receptors in the master clock in the brain. And by doing so, it actually increases peripheral vasodilation, so blood flow to your extremities. And by doing so, it increases that radiator effect that we spoke.

• 1:30:46Chris Williamson?

  Core temperature manipulation again.

• 1:30:49Speaker 01

  Yeah, facilitates that drop. And there have been a couple of studies showing that taking glycine helps people fall asleep faster and sleep slightly longer. Again, the quality of that research isn't that high. But if you look at the effects of glycine on other things that's being studied for things like. Lifespan extension and also joint integrity, then I I wouldn't really hesitate to recommend that. And the other thing is that the amino acid composition of most people's diets now is probably quite different from our distant ancestors in that once ate nose to tail. People nowadays don't really, and the majority of meat people eat is muscle meat, and for

• 1:31:30Speaker 01

  that reason they miss out on the types of, or the s- the same proportions of amino acids that they once would have got in their diets eating in a more natural way. And glycine is one of those amino acids that they may be skimponed.

• 1:31:44Chris Williamson?

  Oh, interesting.

• 1:31:46Speaker 01

  I wouldn't hesitate to try glycine. It also tastes like sugar and you can take three grams of that about an hour before bedtime and see if it helps.

• 1:31:52Chris Williamson?

  Okay.

• 1:31:53Speaker 01

  It's very cheap, too. I I recommend that before taking melatonin.

• 1:31:57Chris Williamson?

  Fantastic. Okay. Well, we've got some nice um so some nice bits to follow there. So I want to ask, I I you've mentioned this this word earlier on. I've got no idea what it means. What's cro- chrono nutrition?

• 1:32:11Speaker 01

  Yeah. So chrono nutrition is the study of the interactions between your diet and your body's clock. So how, for example, does when you eat influence the timing of the various clocks in your circadian system? Or what are the implications of when your circadian system is best prepared for various activities on when you should eat?

• 1:32:39Chris Williamson?

  Okay.

• 1:32:40Speaker 01

  It's that reciprocal relationship.

• 1:32:42Chris Williamson?

  I understand. So we're going to go on to ways to enhance circadian system function and chrono nutrition ties in quite nicely here. Is the uh would you, how highly would you place chrono nutrition on the list of ways to enhance your circadian system function?

• 1:33:02Speaker 01

  For most people, I would say that it's probably quite important. It's a very nascent area of study. There aren't many researchers that have spent many years looking at it. But so far, the evidence is very interesting. And I don't think that many people think about it. And for that reason, it might be a low-hanging fruit. Everybody historically is focused on what they should be eating and not when they should eat. And being more consistent in eating patterns and restricting them to your biological daytime, so not the time of day at which your body's saying, "I should be sleeping now", is smart for many reasons. And there are many different directions that we could go with this.

• 1:33:47Speaker 01

  One more thing that I'll mention is that whereas the light-dark cycle is the main time cue for the master clock in your brain, your diet seems to be the main time cue for many peripheral clocks, by which I've just meaning all of those clocks outside the master clock in your body. So that actually means other clocks in your brain too. But the clock in your liver and your gut and your skeletal muscles and so on. And your fat tissue. So many people, they eat in very haphazard ways. One day, they wake up in the morning and they have breakfast at 6:00 a.m. and they have dinner at 10:00 p.m. The next day, they skip breakfast. They have their first meal at 1:00 p.m. in the afternoon. And then they have their dinner at 6:00 p.m.

• 1:34:32Speaker 01

  And that type of inconsistency seems to be a bad thing. If you take people under very rigorous conditions, and in one condition, they have a consistent number of meals each day, and in another condition, they take exactly the same food and they distribute it into a varying number of meals, then at the end of those two periods, the people who've had the varying number of meals would tend to burn fewer calories in response to eating. Their blood sugar regulation would be worse. And their blood lipid profiles would be worse too.

• 1:35:06Chris Williamson?

  Right, okay, that's interesting.

• 1:35:08Speaker 01

  In healthy young women. So consistency is important. Another consideration is the duration of the caloric period. And I say caloric period because I could talk about eating period. However, many people now will have some sort of concoction from Starbucks that has 800 calories.

• 1:35:28Speaker 01

  And they might as well be drinking a blended lasagna or something.

• 1:35:34Speaker 01

  Because actually it has the same things in it. You know, you you have large quantities of fat in it and calories and so on.

• 1:35:41Chris Williamson?

  Yeah.

• 1:35:42Speaker 01

  I I think it's more useful actually to think about a caloric period. So when am I consuming calorie containing items? And even more useful actually to think about when am I consuming items that aren't just water? And trying to make that consistent.

• 1:35:56Chris Williamson?

  I was gonna say, so you'd included in cal- uh, things that aren't just water would be coffee, for instance?

• 1:36:03Speaker 01

  Yeah, and I I would throw things like coffee and tea in there, even if it was coffee without milk and sugar. Because coffee contains caffeine, and we haven't really spoken about this, but caffeine per se does seem to influence the circadian system too. At least in cells and probably in humans too. It's been shown that if people consume caffeine late at night, then they delay their melatonin synthesis onset in the evening in constant conditions.

• 1:36:27Chris Williamson?

  Okay.

• 1:36:28Speaker 01

  So anyway, that period probably is relevant too for a lot of people. I think consistency might be the most important thing, but people now are looking at these so called time restricted eating studies.

• 1:36:39Chris Williamson?

  Sixteen eights or like twenty twenty, twenty fours and stuff like that with intermittent fasting, right?

• 1:36:46Speaker 01

  Yeah, exactly. And and there's been, there are a few people who are very vocal about its benefits. But actually, if you look at the entire body of literature on the subject, there just aren't many studies on it at the moment.

• 1:37:00Chris Williamson?

  I mean, uh, anyone who's pervaded Reddit recently will know that between intermittent fasting and no fap. You have, you have like the two most militant dogmatic cultures, subcultures. Of people who swear that they get hu- superhuman benefits from eating four hours out of twenty or eating after twenty four hours of fasting or not touching the penis.

• 1:37:33Chris Williamson?

  I mean, I don't know. I wonder how many people are doing intermittent fasting and no fat together. That must be a pretty miserable existence. But yeah, it's um, both of them seem to be from a similar kind of camp.

• 1:37:47Speaker 01

  Yeah, and I I think that it it probably is useful in some circumstances. So what does the evidence show so far? It shows that if you take people and in one condition, they're allowed to eat when they want, and in another condition, they restrict their eating period. Typically, what happens is the people who restrict the eating period or the caloric period will consume fewer calories, but they'll also expend less energy over the day. So they specifically tend to engage in less non-exercise activity thermogenesis, which is just fidgeting, and probably take a few fewer steps each day, too. And the net effect of that is that they burn less energy, they consume less energy, and therefore remain in energy balance, as as they did in the other condition in which they just eat when

• 1:38:32Speaker 01

  they want to eat. So that that doesn't seem to be beneficial. And there are a couple of very nice studies that have shown that, two coming out of the University of Bath, and also some work from the US, too. So body weight seems to be relatively unaffected. Then there's blood sugar regulation. If anything, skipping breakfast specifically is one way to shorten the eating period, seems to impair your ability to regulate your blood sugar later in the day. Your blood sugar levels in response to consuming meals are more variable, and that variability is somewhat predictive of the development of metabolic diseases subsequently, like diabetes.

• 1:39:11Chris Williamson?

  Okay.

• 1:39:12Speaker 01

  So that's not a beneficial effect. And then almost everything else that's been studied, it doesn't really seem to be having a strong effect on. If anything, it seems to increase inflammatory responses to feeding, which also probably isn't a beneficial effect. Am I saying that it's never going to be useful? Absolutely not. But I think that these kind of compressed eating periods aren't necessary for a lot of people. I think that at the moment. There are too many people jumping on the bandwagon and saying that this is enormously important when so far the science doesn't really show that. It does show that in rodents. If you look at mice, for example, then it is very protective against metabolic disease development.

• 1:39:57Chris Williamson?

  It's longevity, right? It's a thirty percent increase, around that number in terms of longevity?

• 1:40:04Speaker 01

  Yeah, all sorts of things. And one of the really difficult things that people are only just starting to tease apart is the effect of restricted caloric periods as distinct from the effects of energy restriction, because often the two have gone hand in hand historically.

• 1:40:26Chris Williamson?

  Yeah. Is it that you're eating less food, or is it that you're eating within this special window?

• 1:40:31Speaker 01

  Yeah. And only very recently have researchers developed the types of methods that they need to answer those questions, even in laboratory animals. So it's going to be really exciting to see what the results of some of those studies are. But anyway, these types of restricted caloric periods are really, really beneficial in other animals. So far, the effects on humans don't really seem to be particularly remarkable, as far as I'm concerned, from what I've seen.

• 1:41:04Chris Williamson?

  Uh huh.

• 1:41:05Speaker 01

  But I do think that they will prove to be very valuable for certain people in certain circumstances.

• 1:41:10Chris Williamson?

  Is that in the same way that keto can be useful for people who suffer from epilepsy, for instance?

• 1:41:15Speaker 01

  Yeah, that's a very good analogy. I think probably actually people with things like gastrointestinal disorders will benefit from restricted eating periods, because you just give the whole tract a break for a consistent period of time each day.

• 1:41:31Chris Williamson?

  Yeah.

• 1:41:32Speaker 01

  So that's one example of a use case which to me makes perfect sense. So there's that. And then there are also certain circumstances in which people are unavoidably inactive.

• 1:41:45Speaker 01

  And if they're just sat at the desk all day and they restrict their caloric period and they end up eating less because they've restricted it and what they eat has absolutely no bearing on their activity regardless, then that might be useful too. So I think that my, my key takeaways would be that you don't want to eat too late at night or as soon as you wake up in the morning, especially if you wake up to an alarm. You want to wait until shortly after you would naturally be awake before you start consuming anything other than water, in my opinion.

• 1:42:20Chris Williamson?

  Okay.

• 1:42:21Speaker 01

  And then also consuming late at night. So let's say within, I was going to give you an arbitrary cutoff, within two hours of when you plan to go to bed is probably ill-advised because one of the things that you see in response to calorie ingestion is that your body has to use energy to break down all of those nutrients. So your core temperature rises and that's going to negatively affect the drop in brain temperature that's necessary to helping you initiate sleep.

• 1:42:48Chris Williamson?

  Mm hmm. It's, um, there's so many nebulous little elements that are contributing to sleep and the quality of sleep. And then, you know, earlier in the discussion, we, we went through just how important it is and why it's important to get good sleep. I think it would be quite easy for someone who's listening to hear any of these individual, uh, individual points in isolation and think, well, you know, like, do I really need to avoid eating? Do I really need to do the hot shot? Do I really need to have the cool room and the fan, sun and so forth? But you think it's one thing that you're going to do absolutely every day. Habit setting to clean your teeth was done when you were a

• 1:43:32Chris Williamson?

  child and now you don't think twice about it. But if I told you to do it, if I told you that you had to spend two minutes, three times a day sticking something in your mouth and you'd never done it before in your life, you'd think, oh, well, that's, that's probably a little bit of a pain in the arse. And, you know, to, to look at optimizing and drilling down to its constituent parts, a process which all of us need to do and which we've already identified is really crucial for short-term performance and health and then long-term health and longevity. You know, I think.

• 1:44:04Chris Williamson?

  There can't really be too much weight applied to people trying to do this. Is there a, do you, you know, especially with Matthew Walker's book, Why We Sleep, it's, it's been pretty widespread. Can you feel a, a change in the tide of the interest in sleep and the appreciation for how important it is in the more, in the wider populace?

• 1:44:24Speaker 01

  Yeah, there's been an enormous shift actually, and I'm grateful in a way because it's coincided with my PhD.

• 1:44:30Chris Williamson?

  I was gonna say, do you feel like you're riding the crest of a wave at the moment?

• 1:44:34Speaker 01

  Yeah, I, I think so. And I don't wanna sound, this could easily come across the wrong way. But anyway, I, I had a paper published in the second year of my PhD, and the paper is entirely unremarkable. It's, it's an okay publication. There was nothing revolutionary about it whatsoever. Basically found that people who sleep less, people who report sleeping less in the UK are on average heavier, have bigger waistlines, and tend to have lower levels of HDL cholesterol, which is just a type of cholesterol that's involved in removing fatty deposits in your blood vessels from where they shouldn't be. And my supervisor decided to send out a

• 1:45:19Speaker 01

  press release on the back of that paper. And it, people went absolutely nuts for it. It was, it was very, very strange. I was interviewed by the BBC World Service. It was in the New York Times. It was in

• 1:45:35Chris Williamson?

  Wow.

• 1:45:36Speaker 01

  USA Today.

• 1:45:37Chris Williamson?

  Were you shocked?

• 1:45:38Speaker 01

  Fuck, I had no idea what was going on.

• 1:45:43Speaker 01

  Yeah, so, so that's, I'm, I'm not saying that to make it out as if I did something great, because I fully recognise that I absolutely didn't. It was just fascinating to behold.

• 1:45:53Chris Williamson?

  It's a marker for how interested people are becoming in sleep, right?

• 1:45:57Speaker 01

  Yeah, it's a perfect marker for it, but what a fantastic development because we have spoke to people like Matt Walker, who is a fantastic scientist. There are very few people in the world, if anybody in the world, who knows more about sleep and memory specifically than Matt Walker. But he's also a great communicator. So the nice thing is that we have a handful of people like him who are spreading the good word about sleep and they're actually generating a lot of momentum and getting in front of the people that they want to be in front of and starting to instigate some change by raising awareness. And over time, more progressive employers and so on are starting to think more about this.

• 1:46:40Speaker 01

  Okay, if our people are sleeping better, then they're gonna spend less time absent. They're gonna be more productive when they're at work and so on. So what are the things that we can do in the workplace to make it more conducive to having people meet their sleep needs? So the tide is definitely there at the moment. And what's interesting is that whereas with diet,

• 1:47:03Speaker 01

  things are repackaged every few years into another fad. And the fad itself more or less delivers the same information in a new way.

• 1:47:14Chris Williamson?

  Like calorie deficit.

• 1:47:18Speaker 01

  More calories. Eating more vegetables for most people is probably smart. Protein helps keep you full and don't eat pizza.

• 1:47:29Chris Williamson?

  If James, if James Smith, P T, is listening, he'll be, he'll be shouting at the mic at the moment because he is the number one proponent of don't buy into fads. You just need a calorie fucking deficit, mate.

• 1:47:43Speaker 01

  Yeah, well, you've had famous instances of that, haven't you? Like off the back of, what was that film with?

• 1:47:54Speaker 01

  The famous journalist who went and ate McDonald's for a period of time, fast food nation, was it?

• 1:47:59Chris Williamson?

  Uh, supersize me.

• 1:48:01Speaker 01

  Supersize me. So he was in really bad shape after that.

• 1:48:06Chris Williamson?

  He was fucked.

• 1:48:07Speaker 01

  And then there was a smaller documentary, by smaller I mean in terms of the amount of attention that it generated in response to that, in which somebody consumed fast food for a similar period of time, but ensured that they were in an energy deficit and almost all of the health outcomes that they tracked improved over that period of time. So calories are important and there are these fundamental things, but what I was getting at is that with diet, you have all these different factions of people. At the moment, everybody is absolutely bonkers for ketogenic diets.

• 1:48:40Chris Williamson?

  Yeah.

• 1:48:41Speaker 01

  Which completely baffles me on a personal level, but at the same time I do understand it. And that will pass and there'll be another one that pops up.

• 1:48:50Chris Williamson?

  Well, I mean, you know, to, to interject there, the, the listeners will know how much I adore Jordan Peterson. And as a thinker, he's fantastic, but as a dietitian, I would not, personally, I would not take his advice. He was sat on Joe Rogan saying, um, last, a couple of weeks ago, that he'd started the carnivore diet where he eats just, he's cut greens out from a ketogenic diet and was never really doing the fat. He eats steak and salt and that's it. And he was saying to Joe, he was like, and I couldn't bloody believe it, you know? I lost 10 pounds in the first month and then the second month I lost 10 pounds and that continued every month for five months. I'm the same weight I was when I was in college. I can't bloody believe it. Like, do you understand how mu-

• 1:49:35Chris Williamson?

  how many calories you're having per day, Jordan? Your MyFitnessPal says probably 1500 calories or less. Like, where did you thi- what did you think was going to happen? Your body's starving. Now, I know that you've, your daughter's autoimmune disease has been cured absolutely fantastic and yourself, depression, mood regulation, all of those things, but you can't attribute the weight loss to some magic manipulation of the, of what you're putting in your mouth. It's the fact that you're not eating very much. He said, oh my, he literally says two minutes after that, you know, I, my, my, my hunger's dropped by 70% at least. I'm never hungry. And I'm like, well, are you fucking surprised? Your body's starving.

• 1:50:17Speaker 01

  It's funny, I actually watched that. Just as an aside, I'm not sure if that was a Canadian accent or an Irish.

• 1:50:22Chris Williamson?

  That's me trying to do Canadian, okay? That's my best Jordan Peterson.

• 1:50:26Speaker 01

  No, but I think there's a pretty accurate recollection. In fairness to Jordan, he did say, I am not a dietitian. And not giving people advice, but the problem is that if it's true and his book is the bestselling book in the world in the last 12 months, then he has this enormous, enormous number of people listening to him and people latch on to that.

• 1:50:45Chris Williamson?

  Yeah.

• 1:50:46Speaker 01

  And all of a sudden, we're going to have the Jordan Peterson Beef Diet, Beef and Salt Diet.

• 1:50:51Speaker 01

  And that's, that's probably not smart. But anyway, to go back to the original point, sleep isn't something that you can repackage in that way.

• 1:50:57Chris Williamson?

  Yes.

• 1:50:58Speaker 01

  So it, it doesn't, I don't think it has the fad potential. I think that various sleep technologies do. And sometimes the fads themselves aren't a bad thing insofar as they continue to engage people with the behaviours that they need to carry out on a regular basis to be healthy. So I don't care if somebody uses a new toy in order to accomplish that. If it keeps them doing what they need to be doing, then that's great.

• 1:51:25Chris Williamson?

  If the focus is on, so if the blue blocking glasses mean that you're thinking about your sleep as a byproduct, then cool.

• 1:51:31Speaker 01

  Exactly. If you're taking melatonin an hour before bedtime and that's the start of your pre-bed routine. And it's a signal to ingrain that habit and get in the right mindset for sleep. Something we didn't touch on earlier is the mindset and just making sure that you have a clear mental conscious before sleep. That, that's great. And it's, as long as that particular behaviour isn't counterproductive. And I'm all for it, really.

• 1:51:58Chris Williamson?

  It's a very holistic view of the subject area and of the, of the market or industry, if you want to call it as a whole from yourself. I can imagine that for some people in other industries, this level of attention would actually be quite threatening. Oh, well, here we go. The charlatans are rubbing their hands together, ready to capitalise on this and start spreading disinformation. But as you say, because it's quite a specialist field, heavily researched to one degree or another, although perhaps not, not entirely understood yet, that there seems to be less opportunity for this disinformation to be, to be pushed.

• 1:52:36Speaker 01

  Yeah, I completely agree. And anyway, I just hope that that particular engagement with the importance of sleep is something that's sustained over time.

• 1:52:47Chris Williamson?

  Fantastic. So I want to, I want to finish on, I want to finish on two things. We're going to go on to human OS in a moment, but the, um, the cognitive function and, and how your, um, how your sleep affects that. Are there any final ways that you think that people can improve if they've had a bad night's sleep? What can they do the next day to just kind of get themselves moving a little bit?

• 1:53:12Speaker 01

  Okay, so I'm just gonna park that for one second and just say first, if it's possible, try to bank sleep before, if you know that you're going to go through one of those days.

• 1:53:22Chris Williamson?

  Yep.

• 1:53:22Speaker 01

  Another thing is that you should plan menial tasks for these days. You're not going to be at your best. You shouldn't be sending important messages that have long-term consequences. And, and also on these days, you don't want to do things that are gonna impair with, impair your ability to get good sleep that night. Okay, so with all of that said, what can you do on those days?

• 1:53:45Speaker 01

  One thing is related to temperature. So slightly uncomfortable temperatures do boost vigilance and they're not going to impair your sleep at all. So if, for example, you can expose yourself to slightly colder temperatures, then you're gonna raise your alertness in the short term. So that can be things like cold showers, but also if you're in an air-conditioned room, then maybe just adjusting the settings will help you maintain alertness during that period of time. Another thing is light exposure. So I mentioned the effects of bright light on cognition. So if you spend lots of time outdoors, that's going to be really important if you're up during daylight. Naps are something that

• 1:54:26Speaker 01

  we touched on, and I, I think that they, they can be really useful. So why would you use a nap? One reason would be improving your ability to form new memories and they improve various types of memory formation. So you have these procedural memories, which are memories of how to carry out a specific task, how to ride a bike, how to... Hit a cricket ball, whatever it might be, you have declarative memories, which are memories of facts. So I know that eight plus six is fourteen, whatever it might be.

• 1:54:56Chris Williamson?

  Uh huh.

• 1:54:57Speaker 01

  Another purpose would be to temporarily boost your energy. So we spoke about how that ten minute nap seems to have the greatest short term effect on your energy levels. Slightly longer naps will have this sleep inertia consequence immediately afterwards, but that will dissipate and then later they'll have stronger alerting effects.

• 1:55:17Chris Williamson?

  Is there a, is there a period of sleep inertia that, how long is that? Is it half an hour? Is it a couple of hours?

• 1:55:23Speaker 01

  It's, it's probably once you pass about twenty minutes or so. As soon as you enter into deep sleep, especially if you wake up from deep sleep, you're going to experience that sleep inertia.

• 1:55:33Chris Williamson?

  Yeah.

• 1:55:34Speaker 01

  These sleep cycles, they tend to last about ninety minutes on average. So let's say that you had a ninety minute sleep cycle and then you woke up at the end of a period of REM sleep in which you're dreaming, you'd probably actually feel okay afterwards. But a half hour nap when you woke up from one of the deepest stages of sleep, then you'd experience that sleep inertia. Another function of naps is your ability to learn new things. So while you're awake, your brain is forming all of these new synaptic connections and during sleep those are scaled down. So your brain figures out, what do I need to hold on to? What's useful information for my long term viability and what's not? And it retains

• 1:56:18Speaker 01

  the useful information and then it frees up new space by pruning away the connections that it doesn't think are important. So it will actually have, it will actually have very valuable effects if, for example, you're a bit short on sleep and you're studying hard for exams, just taking that nap will both enhance your memory consolidation, but then also free up some space for you to learn new things too.

• 1:56:42Chris Williamson?

  Hmm.

• 1:56:43Speaker 01

  Naps will also boost your immune function temporarily and after sleep deprivation, for example, having both nocturnal sleep and a nap has an additive boost on immune function and then naps will buffer against the effects of losing sleep. So if you've lost some sleep.

• 1:57:00Chris Williamson?

  So what you're saying is that sleep's the panacea, the nap, the daily nap is the, is the cure?

• 1:57:06Speaker 01

  Well.

• 1:57:08Speaker 01

  Are very short on sleep, then actually just just having a brief nap, however brief it is, is often going to be really, really useful.

• 1:57:16Chris Williamson?

  I mean, who'd who'd have thought that if you if you're short on sleep that the solution was to try and get some sleep?

• 1:57:21Speaker 01

  Yeah, I know.

• 1:57:23Chris Williamson?

  So I want to move on to Human OS. Can you can you try and explain for the listeners what that is?

• 1:57:30Speaker 01

  Yeah, so

• 1:57:33Speaker 01

  we live in an age when we have different apps for everything related to our health. So you have a meditation app, you have a Fitbit on which you track your physical activity and your sleep, and then maybe you go to various websites for information about about how to live a more healthy lifestyle. And what we try to do at Human OS is consolidate all of that in one place. So Dan's created, Dan, the CEO, has created this loop model to sustain health behaviours. And the fundamental premise is that we educate people about what they need to do to be healthy. We let them track their behaviours to see if they're carrying out those behaviours. And then we also let them see if those behaviours are moving the needle in the right direction.

• 1:58:18Speaker 01

  So it's a platform that you can sign up for and it will integrate with various wearable devices, so things like Fitbits and Emfits and so on. We create online courses about things like diet and sleep. We have a podcast and a blog to which I regularly contribute. And

• 1:58:38Speaker 01

  we have various plans in the future also to pump out protocols to help people navigate certain common situations that we all face on a regular basis. So, for example, I'm short on sleep today. I don't want to mess with my sleep. What shall I do? What what's everything that I can do in order for me to be at my best in these circumstances without having a long term negative effect on my health?

• 1:59:03Chris Williamson?

  So it's the SOS button for a for a couple of situations that might happen.

• 1:59:09Speaker 01

  Yeah, yeah, exactly. And we also try to bridge the gap between the information and the actual practice. So for example, we have courses on cooking and there are daily workouts. So it's just somewhere you can check in each day to keep you engaged with the behaviours which ultimately are important for your health and to try and make it sustainable and fun.

• 1:59:31Chris Williamson?

  That's awesome. Well, I'm really excited to get stuck into the site. I signed up earlier on. I know that very kindly Eric from Human OS HQ has set up a discount code. So for anyone who's listening who wants to check the site out, you can sign up for free for the basic version. Or if you use the code MODERNWISDOM, you can get one month for a dollar at humanos.me. Is that correct?

• 1:59:56Speaker 01

  Perfect.

• 1:59:57Chris Williamson?

  Fantastic. So Greg, would you be able to tell the listeners where they can find you online, please?

• 2:00:03Speaker 01

  Yeah, I'm just going to point them towards everything human OS related. So humanos.me, you can find humanos.me on Facebook and Ginny, who is another of my colleagues there regularly puts things up there. Just views and news and brief synopses of interesting studies that have been published recently. There's human OS, at human OS underscore me on Twitter. And I would say, check out the podcast and the blog. So the podcast is something that covers sleep in great depth, but also a variety of other topics, particularly focusing on various advances in technologies that could be various promising encountering things like

• 2:00:48Speaker 01

  aging in the future and technologies that consumers can use to improve their engagement with these important behaviours too. And then also have a look at the blog. So that is everywhere you can find you know S online.

• 2:01:04Chris Williamson?

  Fantastic. Well, Greg, I really appreciate your time. It's been a there's been an awful lot to learn there. And I thought I genuinely thought coming in that I was going to hear just a a repackaged information that I either knew anecdotally or I knew from reading online or from Matthew Walker's book. But it seems like the the subject area is so so complex and and there's so much for people to to understand that it. I really like what you say about people having to engage with it as a

• 2:01:38Chris Williamson?

  a cared about metric of their health, a cared about habit that they have to do as opposed to just that thing that happens at night. And hopefully we've helped impressed on people today, just how important it is and some of the tactics they can do to help.

• 2:01:54Speaker 01

  Sure. And view them as tactics too. So I don't want people to feel overwhelmed by the number of different things that we've spoken about. I would just say, okay, this is your lifestyle at the moment. You think that that particular behaviour is something that you can easily try. Give it a go. You don't have to try anything else. And actually, having that type of attitude where you just see yourself as a self experiment. And you try all these different things that you think, okay, that might help me, probably won't hurt me. I'm just gonna trial it for a period of time and see how I get on. Is a really healthy attitude to making sure that you can just keep doing what you need to do in a long time.

• 2:02:35Chris Williamson?

  I agree. Well, Greg, thank you so much for your time. Good luck with the human OS me development. I will be keeping keeping my eyes peeled very, very closely as you as you release more of your content.

• 2:02:47Speaker 01

  Thanks a million, Chris.

• 2:02:48Chris Williamson?

  Cheers, mate. Bye bye.