The World’s No.1 Sleep Expert: The 6 Sleep Hacks You NEED! Matthew Walker

When you're struggling with sleep in the. middle of the night, and you're wide. awake in the last hour before bed, try. this experiment. I'm I'm sold. Matthew Walker. Neuroscientist and best-selling author. And one of the world's leading. researchers in sleep science. It's going. to blow your mind. There's a global sleep loss epidemic. shaped by this thing called the modern. world. What society wants is that you're. either producing or you're consuming. In. fact, the CEO of Netflix is stating was.

that we ought to commit war against. sleep. We have this mentality in. business. Less sleep equals more. productivity. That is just not true. Insufficient sleep costs most nations. about $411 billion. Jeez. Your rates of obesity, cardiovascular. disease, mental health conditions, all. of these things escalate. If that wasn't. bad enough, Oh my god. if you're not getting sufficient sleep, then 60% of all of the weight that you. lose will come from lean muscle mass and.

not fat. Not the muscle. How would you redesign. society to help us to sleep better? So, first I would. Feels like caffeine is a miracle drug. with no apparent cost. Was I wrong or. was I right? Wrong. Caffeine will hurt your sleep in. three ways most people are not aware of. So, if you have a cup of coffee at. midday, what happens is that. Before we get into this episode, just. wanted to say thank you first and.

foremost for being part of this. community. Um the team here at The Diary. of a CEO is now almost 30 people, and. that's literally because you watch and. you subscribe and you um leave comments. and you like the videos that that this. show's been able to grow. And it's the. greatest honor of my life to sit here. with these incredible people and just. selfishly ask them questions that I'm. pondering over or worrying about in my. life. But this is just the beginning for. The Diary of a CEO. We've got big big. plans to to this show um to every corner. of the world and to to to diversify our. guest selection and that's enabled by.

you by a simple thing that you guys do. which is to watch. So, if there's one thing you could do to. help this show and to help us continue. to do what we do, it's just to hit the. subscribe button. If you like this show, if you like what we do here, if you. watch these episodes, please just hit that subscribe button. Means the world. Let's get on with it. Matt, I have spent the longest time trying to. sit down with you on this podcast. So,

I'm very very happy to spend some time. with you today. And that is because your your work is. now world-renowned um and it's very very. important work. But, as is the case with a few of the recent. episodes in this podcast, I wanted to. start by asking you, in your view, what is it you do and why is it so. important in your mind that you do it? Well, firstly, thank you so much for. having me here and having this.

conversation. It's an incredible. privilege to sit with you. Um. why do I do what I do and why do I think. it's important? Um. sleep, I would argue, is the single most. effective thing that you can do to reset. your brain and body health. And I don't say that flippantly. It's. not as though I'm dismissing exercise or. diet. Those two things are absolutely. critical. But, if I were to take you, the. individual, and deprive you of exercise.

for a day, deprive you of food for a. day, deprive you of water for a day, or. deprive you of sleep for a day, 24. hours, and I were to map your brain and. body impairments, it's not even a. competition. That one night of lost sleep relative to. those other things, it dwarfs The only. thing I lose out against is oxygen. If I. deprive you oxygen, you're going to pop. out. of existence a little bit quicker than. you will with a lack of sleep. So,

sleep to me, I think, is the elixir of. life. It is your life support system. And as best we can tell, I would argue. it's Mother Nature's best effort yet at. immortality. And so in that regard, that's why I when. I look across all of the studies and all. of the data, it's so compelling to me. And part of the reason I think it's I've. desperately tried and I haven't done a. good job, but I've tried to offer some. public mission of reuniting humanity.

with the sleep that it's so bereft of is. because it does appear that there is a. global sleep loss epidemic. If you look. at the numbers, people are struggling so. desperately with their sleep. So we have. all of this knowledge, this incredible. knowledge of sleep and how important it. is. And it's a perfect storm colliding with. this great sleep depression in modern. society. And for that reason, I just. felt as though what can I do to try to. help, offer this voice and this science.

And I am but a scientist and I stand on. the shoulders of all of my colleagues. and all of these giants in the field. I'm just a researcher, so that's a. little bit about I guess who I am, but. more about why I do it and why I think. it's important. If I were to try and define your sort of. And this I hate doing this because it. requires the application of some kind of. narrow label. If I was to try and define. what your title is in your own words, what would that be? So I'm just a professor of neuroscience,

of brain science at the University of. California, Berkeley. Um I am I am not a medical doctor, just. FYI for all of the things that we will. talk about in this conversation. Uh so. I'm just a PhD. Just a PhD. Yeah. You know, that's um. incredibly humble of you, but but I. would assert that you're without a. shadow of a doubt the leading. author, scientist, commentator, voice as. it relates to the topic of sleep. And my my my question from that is,

where did that begin? Like, where did. that start in your life, in the journey. of your life? When did sleep become the. thing? It occurred to me or happened to me, I. should say, when I was doing my PhD. I. was studying people with dementia and we. were trying to understand what type of. different dementia that they had very. early on in the course of the disease. And we were looking at patterns of brain. wave activity. So, I was placing.

electrodes all over the head and I was. measuring them and I was trying to. differentially diagnose them very early. on and I was getting no good data. whatsoever. I was miserable. Nothing was. was landing. And one day I went home uh at the. weekend and sort of with all of my. printed journals and I go to the my. doctor's residence and have this sort of. eggloo of journals around me that I. would sit and read at the weekend. Um, and I was which probably tells you. everything about my social life at the. weekend if that's what I was doing, but.

um so I was reading these journals and. it occurred to me that some of these. dementias were eating away at the sleep. centers in the brain and others would. leave them untouched. And at that moment. I realized I'm measuring my patients at. the wrong time. I'm measuring them when. they're awake. Should be measuring them. when they're asleep. Started doing that, got amazing results. And at that point I wanted to ask the. question, well, I wonder if the sleep. problems are not simply a symptom of the.

dementia. I wonder if it's a potential cause of. the dementia. And at that point I started to think, well, so then what is this thing called. sleep? And what I learned is that some of the. greatest minds in the past 100 years had. tried to answer a very simple question. Why do we sleep? And you know, 30 years ago in fact, the. crass answer was that we sleep to cure. sleepiness.

Which tells you nothing about you know, it's like saying, I eat to cure hunger. Well, no, you that's not the right. answer. Now, 30 years later, we've had to upend. the question and we now have to ask, is. there any physiological system in your. body? Is there any operation of your. mind that isn't wonderfully enhanced. when you get sleep or demonstrably. impaired when you don't get enough? And the answer seems to be to be no. there. So, my journey into the science.

of sleep really was an accident. But at. that moment in time when I started. reading about sleep, I utterly fell in. love with the topic. And it is a love affair that has lasted. me over 20 years. I think it is the most beguiling topic. in all of science. I'm biased of course. Um and I will never study anything. different. I know that now. I'll study. it to the end of my career and until the. end of my life.

Wow. I've never heard anybody say to me on. this podcast that they would study. the same topic for the rest of their. life. And you're a young man. That's a you've. got a long way to go. Actually, the amount you've been. sleeping. It's very kind of you to say. I I wish. I'm I'm moving into the foothills of. middle age rapidly, but. no, I. I'm so fortunate in what I do. to have found it or for it to have found. me. You know, if I won all of the money. in the world tomorrow,

I would genuinely genuinely not do. anything different. Um, I am so fortunate Well, I probably start. trying to fly like business class or. first class. That would be nice. But. other than that, um, I would do nothing. different. And I. I'm very mindful of that because that. sounds very privileged. And I know a lot. of people. endure what they do for a living rather. than enjoy what they do for a living. And I know how lucky I am. So, I don't.

mean to be dismissive of of people in. that God, I just know how much I love. what I do. You you asked a question now which is, um, you you you posed a question which. many people have tried to answer. You. gave the the answer from 30 years ago. about, you know, why do we sleep? Um, and it dawned on me as you said that. that I've never asked myself that. question. I've never even pondered the thought of. why I sleep. I mean, I know what happens. when I sleep. But do I know why my body. can't just find another way? Why can't.

my body stay awake for the 24 hours? I. know some animals, they sleep half their. brain and then the other half kind of. has a nap and whatever. Why why why do. we sleep? It it's a puzzling question because when. you think about it from an evolutionary. perspective, it makes no sense. whatsoever. Sleep is utterly. idiotic because when you're sleeping, firstly, you're not finding a mate, you're not reproducing, you're not. foraging for food, you're not caring for.

your young. And worst of all, you're. vulnerable to predation. Now, on any one of those grounds, but. especially all of them as a collective, sleep should have been strongly selected. against during the course of evolution. But from best we can tell, sleep evolved. with life itself on this planet. And it has fought its way through. heroically every step along the. evolutionary path. And what that has told us is that sleep.

must be essential at the most basic of. biological levels. And now we understand that Mother Nature. didn't make a spectacular blunder with. this thing called sleep. Sleep, for. example, will restock the weaponry in. your immune arsenal. And it will make you a more. immune-sensitive individual. So, you're. more immune-robust. when you wake up. We also know that it regulates your. blood sugar levels. It controls your.

appetite hormones. It also regulates. your sex hormones, testosterone, estrogen. Um sleep upstairs within the brain will. fixate memories and help you learn and. remember. Sleep will de-escalate. anxiety. It will reduce your emotional. difficulties and traumas. Sleep will. actually cleanse away the Alzheimer's. toxic proteins that build up in the. brain. You know, the list is endless. These are all of the reasons that we. need to sleep.

But why can't I just do what those. animals do where they half of their. brain falls asleep and the half of the. brain stays awake? Is that at all linked. to the fact that we we live in tribes? So, we are essentially, although we're, you know, there might be 10 people in. the tribe, we're. all 10% of the tribe. So, we can rest at. different times and kind of cover each. other's backs or. Gosh, yeah. So, actually, there are two. nested. very insightful questions there. The. first is this notion of what you're. describing with just what we call.

unihemispheric. sleep, which is just a fancy way of. saying you can sleep with one half of. your brain and the other half is wide. awake. Now, there are only a few species. that can do this. Um for example, aquatic mammals, dolphins are great. example. We can place actually. electrodes on their heads and you can. see that one half of their brain will be. fast asleep. It will be in deep, deep. non-REM sleep. The other half of the. brain will be frenetic, wide awake.

And in part for them, the reason is. because they need to maintain aquatic. mobility. You know, they need to keep. surfacing for air, otherwise, you know, that's not going to be a good outcome. We also know that. uh. birds or even many avian species will. have unihemispheric sleep. And you can. actually see this. There's some great. YouTube videos online where they will. film one half of the sort of the side of. the the bird's face and the eye is. closed. And what it means is that the.

other half of the brain, cuz the brain. is actually the left half controls the. right side, the right side controls the. left side. So, that left side is now. fast asleep, which is the right eye. closed. And then you kind of pan around, and all of a sudden, the other eye is. wide awake, and it's clearly looking. about. Now, this is obviously not for. aquatic surfacing to gain air. This is. for a different reason. What happens is. that in a flock, a bunch of birds will. all land on a branch. Now, all of the folks in the middle,

they get to sleep with both halves of. their brain. They can sleep with both. halves or just one half. All of the folks in the middle, they get. to sleep with both halves. The. unfortunate girl or guy who sort of. lands at the end, the far end, they will actually sleep with one half. of their brain. So, one half of the. flock, the entire flock, has one eye, 180° of sort of half panoramic view. uh out. The other bird on the other end.

will have the other half of the brain. asleep with the other eye awake, giving. the other 180° view of protection uh. vision. And therefore, the entire tribe. has a 360°. assessment. Now, you would think, in. fairness, that once those guys or girls. at the end have done their duty, they. get to move into the middle and they get. to sleep with both halves. No, that's. not what happens. What they will do. after a while is that they will stand. up, they will turn around 180 degrees,

sit back down, and switch the other. sides of the brain. Wow. So, to to just be clear, the complexity. of wiring and architecture that has to. happen for one half of the brain to be. deep in sleep and the other half to be. wide awake is astronomically hard. I. mean, it's incredibly difficult to. create that wiring. What that tells me is that if sleep was. dispensable, if it was negotiable,

then Mother Nature would have just found. a different way for us to get all of. these brain and body benefits and not. gone to all of the evolutionary trouble. of figuring out this fancy wiring for. half-brain sleep. In other words, you. just can't get away from sleep. You have. to sleep. But, your second question, I. think, is is even more fascinating, which is as as a tribe, because we are a. tribe species. Now, there is something else that we.

call your chronotype. Are you a morning type, evening type, or. somewhere in between? And by the way, you don't get to decide. It's not your choice. You know, this. notion of these go-getter type A's who. say everyone has to be awake at 5:00 in. the morning, you know, you. go to the gym, you blast out a workout. for an hour, and you're at the desk by. 6:00 a.m. Um. you have no choice. If you're an evening. type, you're an evening type. It's. hard-coded. We know that right now.

there's at least 22 different genes that. dictate what you are, morning type, evening type, or somewhere in between. It's about a third-third split across. the population. Why is it a split? Why are we nicely. spread out across our chronotypes? For. exactly the reason you described. Because when we're in a tribe, if we all. sleep at the same time, we're all. vulnerable for 8 hours. But if you were to insert some genetic. variability into when people have a. desire to sleep, you've got the morning.

types who maybe go to bed at 9:00 p.m. and are waking up, let's say, at 5:00. a.m. And then you've got all of the. extreme evening types who are going to. bed at 2:00 a.m. and waking up at maybe 11:00 or midday. So that way, the everyone gets their 8. hours of sleep, but the entire tribe, the nucleus of this group of Homo. sapiens themselves, is only vulnerable. for maybe just 2 or 3 hours. So it's a. clever solution that Mother Nature has.

come up with to say, "Everyone gets. their 8 hours, but as a species, you're. only going to be vulnerable for 2 to 3. hours max when everyone at least as a. collective is sleeping.". Absolute genius. I used to think it was a load of. nonsense, this this chronotype thing. Um. it was actually on this podcast where I. learned about its existence, and then I. went on YouTube to learn more, and your. video came up of you explaining it. Because I thought I always pondered why. my partner. goes to bed super early, wakes up super early. I go to bed late,

wake up late. Um. I'm going to ask you this question. actually cuz it cuz I've I've wondered. this. In that situation where I'm. sleeping in bed with a partner that has. a different chronotype, Yeah. it can have an impact on my sleep, right? Because of the way that the our. sleep cycles work, and the REM sleep, and the stage one, deep sleep, etc., etc. If she's woken up when I'm pulling. into REM sleep, I if she's woken up at. 5:00 a.m., but at 5:00 a.m. because I've. gone to bed late, my REM sleep has just. begun. That has quite a significant impact on.

me, right? If she is waking you up, Yeah, if she's wake if she wakes me up, then it's non-trivial. And likewise, if. you're waking her up as you're getting. into bed on the front end of sleep. So, it's very difficult one of the. things that couples will cite if they. break up. Firstly, is. usually about a third of them will cite. sleep difficulties or sleep issues as a. as a cause of the the breakup or at. least as a contributing factor to that.

breakup. 1/3? Yeah. Jeez. That it's one of at least one of the. factors. When you go with then in and when you. double click to say, "Okay, then what is. it about this sleep kind of tension. between the two of you?". One of those things is a mismatch in. chronotype. And you can see this when, you know, people I think this, you know, on dating. profiles now someone was telling me. people will even say like, "I'm a. morning type or I'm an evening type." As. if you're stating up front this is part. of my identity and just FYI be.

forewarned because maybe it's been an. issue for them in the past. This is why I often speak about. the notion of what's called a sleep. divorce to prevent a real one. Now, it's not for everyone. Um a sleep. divorce is where you sleep in separate. locations. And when we've surveyed people um both. uh you in the from the sleep council in. the United Kingdom and also in the. National Sleep Foundation here in. America,

the data is about the same. One in four. people will say that they sleep in. different locations with their partner. So, almost a quarter of. people in relationships will sleep in. different locations. We think it's. potentially an underestimate because if. you survey people anonymously, then a third of them will report waking. up at least in a different location the. next morning. And part of the reason that it's a taboo.

is because people think, "Well, if I'm. if we're not sleeping together, then. we're not sleeping together." The exact. opposite is true that when a couple is. sleeping well, we know that the sex hormones are. improved, testosterone men, estrogen, um. and uh. uh luteinizing hormone in women. We also. know that your. um desire to be intimate with your. partner is increased. Uh what we found. is that for an hour of extra sleep, if a.

woman gets an hour of extra sleep, her. libido desire to be intimate with her. partner increases by 14%. Now, to give you some context, the FDA. drugs for improving or increasing libido. in women, drugs such as Vyleesi here, clinical drugs, they will increase it by. about 24% and that's a pharmacological. agent. But here, just the added. non-pharmacological benefit of 1 hour of. extra sleep will get you more than 50%. of the way there.

So, I want to just remove that notion of. the stigma. of that if you're not sleeping together, you're not sleeping It's usually quite. quite the opposite. Um I would say that. part of the the challenge, though, is. that. if we look at all objective measures, if. I measure your sleep and the sleep of. your wife, if when you're sleeping separately. versus when you're sleeping together,

it's very likely that objectively you. will both be sleeping worse when you're. sleeping together. That's what the. science tells us. However, what's. interesting is that when you survey. people and say, "How satisfied are you. with your sleep?" which is a subjective. measure, people will say, "I'm actually. more satisfied with my sleep when I'm. with my partner than when I'm sleeping. alone." So, there's a mismatch here. Objectively, your sleep is better, but. subjectively, you still prefer that. And.

of course, it's natural. you know, we. there is safety, there's security in. co-sleeping, there is this. sort of connection that we get. You You can approach it if you want. Just be honest with yourself. And be honest with your partner. And you can start by saying, "Look, this. isn't forever. I just want to say let's do an. experiment for a week, 10 days. Let's. Let's just try it and see how it goes.

It doesn't need to be permanent.". Because what you actually miss. are the bookends of sleep. For the most part, the two of you are. not conscious for most of the experience. of sleeping together. It's really getting into bed and sort of. having a kiss or a cuddle or and sort of. waking up together in the morning and. sort of. Now, obviously, when you're a mismatched. chronotype, that's also can be a. challenge, too. So, you can still have a. sleep divorce, but you can set up a a. system where you will go in, you'll say. your good nights, and you'll kind of get.

into bed, have a kiss and cuddle, and. then you retreat to a separate location. And you can repeat that same process. Um. so, I I don't want to sort of. belabor the point of a of a sleep. divorce, but um people can certainly. explore There is something called a. halfway house, which is called the. Scandinavian method, which sounds far. more salacious than it actually is. It's. simply that you buy two beds, and you. put them side by side in the same room, and therefore, the amount of disruption,

physical um disruption that happens by. way of sheets and movement, is. decreased. But that doesn't solve it all. Sometimes. there is snoring, uh sometimes there is. sleep talking. Those things are not. obviated by the Scandinavian method. When you think about where society is, I. was I was I was going to ask you, you. know, you said you wanted to to do the. work you're doing now for the rest of. your life. Um so, do you think the work you're. doing now is going to become. increasingly more important and. relevant.

I mean, is the problem going to get. worse? Mhm. Or is it going to become less. significant and less relevant? Based on. the trajectory of societies, do you see. it? You know, I'm. mixed. I think when I wrote the book, I. started writing uh. the a book that was called Why We Sleep. back in probably about 2014 or 15, and. at that point sleep was the neglected. stepsister in the health conversation of. that day. You know, we were speaking a. lot about diet and exercise, which was.

wonderful, but there was no voice of. sleep. And I was so sad about that because I. could see so much disease and suffering. that was coming so clearly by way of a. lack of sleep, but it wasn't there on. the public buffet menu for consumption. of knowledge. And so, that was part of the motivation. for trying to write the book. So, I. would say now, and this is not because of me or the. book or anything like that, but is is.

sleep more of a conversation in this day. and age than it was six or seven years. ago. I think I would say yes, there is a. greater awareness of of sleep. Um. but. with that awareness, I want I think one can still question. the pragmatics, meaning. just because we're talking about it more. does not mean that people are still. failing to either get the sleep that.

they need or that they are unable to get. the sleep that they need. And those two. things are different. One is that you. are healthy and you can generate the. sleep that you need, but you don't give. yourself the opportunity, time, or life, I should say sometimes, cuz it's. sometimes not your choice. Life does not. give you the chance to get sleep. And if. only you had the chance, you could. sleep. That's one version. The second. version is, "No, I'm giving myself the. right opportunity to sleep, but because. I'm anxious or because of other issues,

I am not able to generate sleep. I. suffer from insomnia and sleep. problems.". So, those two things I don't see having. changed since. you know, I think this public movement, this increasing movement of sleep. conversation came on the table. So, in. that regard, I'm more pessimistic than I. am optimistic. And I think it will only. get worse. If you look at rates of. insomnia, for example, they're only. increasing. They're only escalating.

Rates of anxiety disorders, the very. same thing. And those two things are. intimately intertwined. So, I think. I wish I my mission was extinguished. within the next couple of years, because. society started sleeping wonderfully. well. I don't think that's going to be. the case. So, I think I've got my work. cut out for me. um to try and help people with better. sleep. Um. Is it So, it's getting We're getting. worse at sleeping? I think.

modernity is making it. so much more difficult for us to sleep. Modernity? What's that? I think it when you think about. you know, we often think about sleep as. a biological process, and it very much. is. And but. also, it's so environmental as well as. biological, meaning. when you were to say, you know, "How did. you sleep last night?" Think about all. of the external factors that changed it.

Well, I had to be up at this time. I had. to catch a flight this time. My partner. went to bed at this time, and she woke. up at this time. There was this noise. that sort of happened. I'm now sleeping. in a hotel room." You know, there are. countless externalities. And those externalities are shaped by. this thing called the modern world. And. in the modern world, if I could really. be cynical, and I'm not someone, I'm. very optimistic and I'm very. non-cynical, but you could argue from a. capitalistic standpoint that society.

does not want you sleeping. Because what society wants from a. capitalistic point of view is that. you're either producing. or you're consuming. And when you're sleeping, you're neither. producing and you're neither consuming. And so, there are lots of ways that I think. society and the modern world has. conspired, willfully or not, conspiratorially or. not, to.

decrease and try to diminish sleep. In. fact, I think the CEO of Netflix several. years ago, and I'm sure that YouTube. comments will correct me if I'm wrong. here, but I believe his very statement. was that we are. we are deciding to commit war against. sleep. That was their goal. And it just stunned me that, you know, that we're going to go to war with. sleep. We're going to remove you from. your sleep. So, there are lots of ways. in in which I think society does not.

help us. Light is another good example. We are a dark-deprived society in this. modern era because we're exposed to. light. We are not giving ourselves the. right temperature cues. You know, we go. into an office where it's you know, 20°. or 70° C, whatever it is, stock-stable. Then we come home and we regulate our. temperature at home to be the same. thing. We take on board probably too much. caffeine in this day and age, although I. am actually an advocate of drinking.

coffee and I can explain why, too. But anxiety, as I said, is a huge issue. All of these things are preventing and. classic roadblocks to sleep. How many of us are getting the sort of. recommended daily allowance of sleep as. a percentage, do you know? It seems to be about. 1/3 of. most modern civilizations. are failing to get the recommended 7 to.

9 hours of sleep a night. 1/3 so roughly 30 35% 33% roughly. Yeah. And does that have geographic variants? I in some countries it's worse and some. countries it's better. I'm thinking. about the UK versus the US or you know, Japan or whatever. Yeah, it is. And in fact, you let me. give numbers to the three countries that. you described. Here in the United. States, the average amount of sleep that. people are getting is 6 hours and 29.

minutes. In the UK, it's not much. better, 6 hours and 49 minutes. Japan. was the worst, 6 hours and 22 minutes. Now, to be clear, that's the average. What that means is that there is still a. large proportion of that bell-shaped. distribution. of people getting even less than that. amount. Now, there are some countries that you. look at that are actually sleeping much.

better than that. I think let me. Mexico for example is is doing very. well. If you look at Mexico City, people are actually sleeping not too far. off from 8 hours. So, there is. variability and we can try to understand. why, which by the way just brings me. back while I think about it to your. comment of will my work be done not from. the because I'm a scientist and I do I. have a run a big sleep center at UC. Berkeley, but the work I do as a.

hopefully a public advocate for sleep. why I don't think it's going to change. um, soon. is because. governments aren't really doing much. about it and I've tried as best I can. and if there is any government out there. that listens to this that wants to work. with me, I'd be delighted. I don't remember and maybe you can, but. any major first world nation government. that has had a public health campaign. regarding sleep. And it stuns me because those same.

governments have had public health. campaigns regarding, you know, eating, regarding smoking, regarding drunk. driving, regarding risky behaviors, safe. sex, loneliness, loneliness, mental health, suicide. Where is sleep in that equation? And it's such a fundamental ingredient. And in fact, almost all of those things. that I've just described.

have an intimate relationship. with sleep. I mean, suicide especially. We were starting to do a lot of work. with this, although it's been hard to. get funding. But what we found is that. insufficient sleep is a precursor to. suicide. That sleep disruption seems to. predict both suicide ideation, in other. words, suicidal thinking, suicide. planning, and tragically, suicide. completion as well. So, if we were to try to have. governments create a public health.

campaign to pull this Archimedes lever. on better sleep, there are so many other. health benefits. You know, sleep is the. tide that rises all the other health. boats. It's almost like a. it's like a mixing deck in a studio. You. know, in those sound studios where. you've seen it. And then there's that. one button all the way to the end, the. white button, sort of that when you move. it up, sort of all of the other dials, the sort of the red, yellow, orange, green dials, they all move up at the. same time as well. There's this like.

sort of one messed like one ring to rule. them all. Sleep is that. Archimedes lever. So, if governments. could only execute on that, the health. benefits would be manifold in terms of. their consequences. It begs the question, you know, if I. were to make you today. president, prime minister, whatever, of. the world, and you had to do, you know, just a few. things to really fix the. lack of sleep epidemic, there you go,

diagnosed it. Um what would those things. be if you were in charge? How would you. redesign society to help us to sleep. better? Gosh, it's such a good question and I've. thought a lot about this. it almost in reverse, which is to say. why is it that we are struggling to get. sleep? And there is no single answer. There are so many different reasons, and. that's why it's actually a very. challenging problem to solve. I would go through a descending level of.

steps. So, first I would start at the. government level, and we would get those. public health campaigns in order. Um next, I would go to the professional. level, because there we have this. mentality in business that, you know, sleep is for the soft among us, that. less sleep equals more productivity. And that is just not true, and I can. provide you with all of the evidence. So, we need to get rid of this sort of.

sleep machismo attitude in the. workplace, where we wear wear our badge. of honor of sleep deprivation on our. arms. We need to get companies to. actually start embracing sleep. And I. can guarantee you, and I can give you. all of the evidence as to why, if as a. company, as a CEO, if you start. prioritizing the sleep of your. employees, you will be far better off as. a company. You will be more. product-based, and you will be more. profitable and revenue generating.

Sleep is the very best form of. physiologically injected venture capital. that you could ever wish for. And in. fact, the RAND Corporation, which is an. independent survey corporation, what. they found is that at a national level, insufficient sleep costs most nations. about 2% of their GDP. So, here in America, that number was. $411 billion. of lost profit caused by insufficient. sleep. In the United Kingdom, it was. over $50 billion. In Japan, it was over $120 billion.

If I could solve the sleep loss crisis. in the workplace, I could perhaps double. the health care benefit for many of. those countries, or I could halve the. out the education deficit in those. countries. So, the next level I would. target is. at business. Then next step down would. be medicine. Medicine is a classic demonstration. here. We have junior doctors, or here in. America, they have doctor residency. programs, where people are working 20-30. hour shifts.

And so, already doctors are inculcated. into the mindset of the uselessness. of of sufficient sleep. Across numerous countries, and I think. it was maybe over eight different. countries, we looked at the medical. curriculum. And we asked, "How many hours of. education do doctors get about sleep?". And what's strange is that, you know, often doctors will you go in and you'll. have an appointment, they'll say, "Okay, you know, how you eating?" And you know, what's going on with the bathroom? How's. the toilet? Um and then, you know, how.

are you sleeping?" As if sleep is one of. these universal health barometers. But. what we found is that most doctors will. only be given about an hour to an hour. and a half of sleep education during. their entire medical school education. Which. blows my mind because it is 1/3 of their. patients' lives, but they're only given. about 90 minutes of education. So, no. wonder your doctors aren't treating your. sleep problems, thinking about your. sleep problems, understanding your sleep.

It's not their fault. And plus, they're. sleep deprived anyway when they're being. trained. Ironically, by the way, doctors, junior doctors who've worked a. 30-hour shift, when they finish that. 30-hour shift and get back in their car, they are 168%. more likely to get into a car accident. because of their lack of sleep and end. back up in the emergency room from where. they were just working, but now as a. patient. I mean, this the paradox,

the irony just stuns me. So, I next. moved down to the level of medicine. Then, I would go to education. because we don't get taught about sleep. in schools. Now, I never got one of. those special classes. You know, I got. sort of, you know, sexual education. classes, classes about drugs. No one. came in and told me about the benefits. of sleep. Why aren't we doing that? Then. next, I would move down into the family. because there is prejudice in families.

with sleep. It's this notion of. parents of teenagers. And these. teenagers, by the way, it's not their. fault. They have a shift in their. chronotype, in their circadian rhythm, that when they go through puberty, when. they're going through adolescence, they. get fast-forwarded in time. So, when. they were 8 or 9 years old, they would. be going to bed, you know, sort of early. in the evening, but now as teenagers, they seem to be stubborn and they're. staying awake, staying awake until.

midnight, 1:00 a.m., and they won't get. into bed. It is not their fault because. they have a biologically wired shift in. the tendency of when they want to wake. up and when they want to sleep. Why am I. bringing this up about this sort of. mismanagement in the home because. parents weekends they'll go into the. room of the teenagers they'll, you know, pull open the the curtains they will. pull the covers off and they say you're. wasting the day. You know, and firstly what they're doing.

is probably trying to sleep off a debt. that we've lumbered them with during the. week because of this incessant model of. early school start times which I'll I'll. come back to. But within the home if you ask parents. of teenagers what percent of parents. think that their teenagers are getting. sufficient sleep and about 70% of them. will say yes, my teenager is getting. sufficient sleep. When you look at the. data only about 15% of teenagers are. actually getting the sleep that they. need. So what happens is a parent-child.

transmission of sleep neglect. They're saying you're lazy, you're. slothful. So then what happens? Well, in. 15-20 years time now that teenager has. got a teenage child, what do they do? They go back in the room, they rip the. curtains open and they say you're. wasting the day because that's what they. were told. So we need to break that down. too and then finally we need to come to. the individual and we need to solve the. individuals sleep problem. So it's a.

very long answer and I'm desperately. sorry to a very big question as to what. I would do if I was off for a day but I. hope that gives you some. sense of of the depth that I think we. need to go to. I've tried to think about. the question a lot. It's not. particularly well executed. I don't. think I was very eloquent there but I. hope that gives a sense. It sounded perfectly eloquent to me. It. sounded like a manifesto so. um hopefully if there are people. listening from governments which I'm. sure there are cuz, you know, I hear about that sometimes which is. quite bizarre but um I.

I'm sure they'll be getting in touch. with you very quickly. Going back to the. top of that that stack on the company. level. So as a CEO or a CFO or an. employer whatever, um there are some. companies that are incentivizing their. team members to sleep, right? Is there. any data showing the efficacy of that? There is data that we have, and it's. bidirectional, both the efficacy of when. you. increase sleep, and also the detriment. when you don't allow sleep. So, a great.

example was, um, NASA back in the 1980s, they were looking at using naps in the. astronaut program, because when you're. up and you're orbiting Earth, you will. actually be cycling Earth, you know, really quite quickly, and you will get. to see, depending on the orbit, maybe. somewhere between 10 to 15 sunrises. every 24 hours, which sounds, I mean,

amazing and remarkable, but trust me, in. terms of your sleep, it is very. dislocating. So, they were looking at how to use naps. strategically to improve performance, because the weakest link on any space. mission, and we've done some work with. NASA, um, is the human being themselves. And they. can cause catastrophic failure. Now, if. you make an error at work, and you're. here terrestrially on the ground, you. know, it's probably non-trivial.

You make an error when you're up in. space, it can be a big deal. So, they were. looking at that. And what they found was. that these naps, anywhere between 20. minutes to an hour, could increase. productivity. on these different tasks by about 34%. and increase general alertness by over. 50%, and in fact, the data was so. powerful that it ended up being. transmitted to all of the terrestrial. workers on the ground that NASA would. start to It was what was called NASA.

naps. It was a NASA nap culture. Now, NASA isn't desperately compassionate by. any means. It's a great organization. But they, just like companies like. Google or Facebook, they understand the. pounds and pennies sense, you know, the. dollars and the cents. version of productivity. So anything that returns productivity, they will invest in. And some of those. companies, you know, I um. I did some work at Google during a. sabbatical. And there on their campus,

they will have these nap pods and they. will have these what are called shh. rooms where you can go and you can take. a nap. So think about 20 years ago, you would. never imagine a company paying you to. sleep on the job. If you were caught. sleeping on the job, you'd probably be. fired. Now companies are incentivizing. it. Not because they are thinking. compassionately or empathetically about. the health or the wellness of their. individuals. It is because they. understand that it transacts marked.

productivity. So NASA was a good. example. When you give sleep, you get. something back. But I can go back to the. reverse of that. Why we think that a lack of sleep does. not equal more productivity is for at. least five reasons. First, when you. survey, and we've we can do these. studies in the in the laboratory, too. When you undersleep employees, they will. choose less challenging problems. So if. you give them an array of work problems, they will just simply, you know, check.

email, they'll listen to phone messages. They don't dig into deep project work. Second, of the problems that they do. take on in their work, they will produce. fewer creative solutions. And after all, creativity and ingenuity. are supposed to be the two engines that. drive businesses forward in terms of. their productivity and their revenue. The third that interesting finding that. we've discovered is that when underslept. employees start working in teams,

they will slack off. They won't do their. work. They will let other people do. their work. It's what we call social. loafing. So, they ride the coattails of. other people's hard work, which won't. breed a good atmosphere in your company. You know, trust me. The fourth thing that we found is that. underslept employees are more deviant. That they're more likely to fudge data. in spreadsheets. They're more likely to. falsely claim uh money for reimbursement. that was inappropriate.

The final thing is that a lack of sleep. will go all the way to the top of the. business chain. What we found is that. the more or less sleep that a business. leader has had from one night to the. next to the next, the more or less. charismatic that employees will rate. that business leader from one day to the. next to the next, even though the. employees themselves, they know nothing. about the sleep that that CEO has been. getting. It's evidential in how. charismatic that CEO is.

So, you can add all of these things up. and no wonder you. if you don't snooze, you lose in the. case of business in that regard. That's. why I can produce, I think, a. non-trivial case for business. By the. way, the other aspect that is hugely. costly to businesses and when I go and. speak to businesses about why they. should value sleep, if you offer it on the grounds of again. sort of compassion or mental health,

they probably don't want to listen. When. you convert it into the cost to the. company and how much it's fleecing them. in terms of their prof- profits, then. they start to pay attention. Underslept employees will. take on average about 11 more days. uh sick days throughout the year. relative to well-slept individuals. So, you're essentially just paying people. additionally for 11 days of work that. they will never give you when you are. under sleeping them. Secondly, the. utilization of health care resources.

increases by about 80%. So, the cost to either you, the company. here in the US where your company is. paying for your health care, or the cost. to the government, for example, in the. United Kingdom is astronomical. And also then the co- what we call. comorbid diseases, your rates of. obesity, diabetes, cardiovascular. disease, mental health conditions, all. of these things escalate as under slept. employees continue to get even more.

under slept. So, there is no strong case that I've. seen. that leads me to think. businesses should foster the mentality. of insufficient sleep. Quite the. opposite. So, that's hopefully an answer. to a question. We can look at it. bi-directionally. When we give sleep. back, do you get productivity? Yes. When. you take sleep away, the things implode. rapidly? Yes. And is it costly to your. company? Very much so. On that point of naps, and you know,

Google sleep pods, naps, and things like. that. There was a point in my life where. I because I learned about REM sleep and. the importance of REM sleep and deep. sleep, and that happens a little bit. further on into my, you know, the. 90-minute Look at me trying to tell a. sleep expert about this. No, I love it. But do you see what I mean? Like, this. is my very This is my monkey brain. So, I didn't understand the subject matter. very well. I still really don't, to be. honest, but in the first It takes me a. significant amount of time to get to. deep sleep into REM sleep. How long on average would would you say.

it takes for it for some, you know, Yeah, so you will probably go into light. sleep in the first 10 to 15 minutes. Then you'll go down into deep sleep. You'll stay there for about 30, 40. minutes. Then you'll start to rise back. up and you'll pop up and you'll have a. short REM sleep period. And then you. complete the non-REM to REM cycle after. about 90 minutes, and back down you go. again, down into non-REM, and up into. REM. So, on average for human beings, it's 90 minutes. So, I therefore assumed that napping.

really does nothing, because I thought, well, it takes me so long to get to REM. sleep and to deep sleep that there's If. I've got 15 minutes, 20 minutes to to. nap, it's just a waste of time. Right. Was I wrong, or was I right? You were. understandably wrong. Okay, good. I'm happy because I I've always rejected. naps because I thought they didn't. matter, because it takes me so long to. get to a restorative state anyway, so. So, we've done lots of different studies. with naps, we and other colleagues, too.

And what we found is that naps can. transact some fantastic benefits. They. can improve cardiovascular health, lower. blood pressure. They can improve your learning and. memory abilities. They can reset the emotional. north of your magnetic compass in a good. way, where you can de-escalate negative. emotions and increase positive emotions. Um so, naps certainly are a good thing, but.

with a big caveat that I'll come back. to. Um yes, you're right in the sense that. to get a full cycle of sleep and to get. into REM sleep, you would probably have. to make that nap about 90 minutes. And. in fact, a lot of the studies that we. do, we will use a 90-minute nap duration. of time so that the brain can cycle. through all of those different stages of. sleep. But you don't need to, nor would I. suggest that you do. What we found is that different stages.

of sleep perform different functions for. the brain at different times of night. There are actually four separate stages, stages one through four, increasing in. their depth of sleep. So, stages three. and four are those really deep stages of. non-REM sleep. Stages one and two, that's the lighter form of non-REM. And then you have rapid eye movement. sleep, or what we think of as dream. sleep. And people will sometimes say to me, "How do I get more REM sleep? Or how do. I get more deep sleep?" And my response. to them is, "Why do you want to get more.

REM sleep?" And their answer is, "Well, isn't that the good stuff?". And it turns out that there is no good. stuff. It's all good stuff. You know, maybe with the exception of that light. stage one non-REM sleep, that's shallow. sleep and we typically don't like to see. too much of that. But stage two non-REM. sleep, three and four, they all have. their different functions that we've. discovered. And REM sleep has its. functions. So, you need all of them. You can't. short short shortchange any of them. But. for a nap,

what we found is that you can get. nice benefits for things like your. learning and your memory, and it can. even reduce some level of anxiety. up to about 20 minutes. You can In fact, you can nap, I think the study one of. the studies, they brought a nap down to. about 9 minutes in duration, and there. were still some basic improvements for. your sort of general level of alertness. and reaction time. For example, if. you're an athlete, that's that's. non-trivial. So, um.

so, the reason I would say. be careful with naps is for two main. um sort of suggestions. The first is, try not to nap for about longer than 20. minutes, because once you go past 20. minutes, you really start to go down. into those deeper stages of non-REM. sleep. And if you wake up after about 45. minutes or 60 minutes, it's not a problem. I'm not suggesting. that you shouldn't or you couldn't. I'm. just saying be aware, because when you. come out of that deep sleep and you wake.

up from that deep sleep, normally that's. not how you wake up. You will usually. wake up out of lighter stages of sleep. or out of REM sleep. It's rare that we. wake up out of deep sleep. But if you. nap and you snap for about 40 minutes, you'll probably go down into deep sleep. And at that point, what if you wake up. and your alarm goes off, then you're going to feel almost. miserable and worse than you did before. the nap, because you have what's called. sleep inertia, which is essentially a. sleep hangover, where the brain is still sort of pulled.

back into that deep sleep state, and it. can take you almost an hour before you. feel like you're back up to operating. temperature and you're up to motorway. speed. So, I would say keep it 20 minutes, and. you don't suffer too much of that. inertia. You still get some nice. benefits. Also, don't nap too late in the. afternoon. Also, the final part is if you are. struggling with sleep at night, if. you're someone who has insomnia or sleep. difficulties, do not nap during the day.

It's the worst thing that you can be. doing. Because. when we're awake during the day, we. build up a sleepiness chemical in our. brain. It's called adenosine. And the longer that we're awake, the. more adenosine that builds up, the more. adenosine that builds up, the sleepier. and sleepier that we feel. And when we sleep, the brain gets the. chance to clear away all of that. adenosine, all of that sleepiness. And somewhere between 7 to 9 hours after. sleeping a full night, the brain has.

evacuated all of that sleepiness. chemical, all of that adenosine, so that. then we should wake up and we should. feel refreshed and restored and not. needing caffeine to to function. Why is that relevant to naps? Well, it's. relevant to naps because when you take a. nap, you're essentially it's like a. pressure valve on a cooker. Pshh, you're. just releasing some of that healthy. sleepiness that you've been building up. And therefore, if you are struggling. with sleep at night, and then you nap.

during the day, it's terrible because. you're taking away all of that healthy. good weight of sleepiness that we've. been trying to build up on your. shoulders to give you the best chance of. a good night of sleep. That's why I would say if you are. suffering from insomnia, don't nap. during the day. Also, even if you are if. you don't struggle with sleep at night, try not to nap after about 3:00 p.m. in. the afternoon or 2:00 p.m. Napping late in the afternoon or in the.

early evening, it's a little bit like. snacking before your main meal. It just. takes the appetite off your sleep. hunger. So, try not to do that. But, naps, for the most part, if you don't. struggle with sleep, they are wonderful. things. Just keep in mind the 20-minute. sort of idea. You mentioned caffeine there. A topic. I've mulled over. over and over again on this. show. Um because as I've said to uh maybe. three or four of my guests now, it feels like caffeine is a miracle drug.

that comes with no apparent cost. But, when I think about things like anxiety. and I don't know, shallow sleep states. I've always pondered that maybe caffeine. is playing a role in that. You said you. you're you're pro-caffeine. You're a. caffeine drinker yourself. So, I am not a caffeine drinker myself, but I am pro-coffee. Oh, okay. And I'm I'll tell you why I'm very. thoughtful about my wording between. caffeine and coffee there. And to your. point, it's a it's another astute one, which is.

it would you know, is it a miracle drug. with no cost? In biology and medicine, there is almost. no free lunch. Um and. that is true when it comes to caffeine. and sleep. So, perhaps I'll give the skinny on caffeine. and how it impacts your sleep, but then. circle back around to what seems an. oxymoronic statement for me, which is. why I'm still pro-coffee.

Um caffeine will hurt your sleep in. probably at least. three ways, some of which you most. people are not aware of. The first issue is the duration of its. action. So, caffeine has what we call a. half-life of about 5 to 6 hours. In. other words, after about 5 to 6 hours, half of that caffeine is still in your. system. What that means is that caffeine has a. quarter-life. of somewhere between 10 to 12 hours.

So, if you have a cup of coffee at noon, at midday, a quarter of that caffeine is still in. your brain at midnight. So, having a cup of coffee at noon, and. it's. hyperbole in truth, probably or it's a. little bit hyperbolic, but it's almost. the equivalent of. a coffee at noon is the equivalent of, you know, tucking yourself into bed and. just before you turn the lights out, you. swig a quarter of a cup of coffee and. you hope for a good night's of sleep, and it's probably not going to happen. So, that's the first thing to keep in.

mind is the. timing of of caffeine. The second is that caffeine is a. stimulant. Now, everyone knows this. Everyone knows that caffeine can make. you more alert and more awake. By the. way, how does it do that? Um, it comes. back to adenosine, which is the chemical. that we spoke about, the sleepiness. chemical. It's no coincidence that those two. things sound the same at the end of the. name, caffeine and adenosine. Caffeine will actually race into your. brain and it will latch onto the. adenosine receptors, the welcome sites.

in your brain. And it has very sharp. elbows and it will force away the. adenosine from those receptors and it. will hijack those receptors. Now, at this point you may be thinking, well, hang on a second. If it's latching. onto those sleepiness chemical. receptors, shouldn't caffeine make you. more sleepy? And the answer is no, because what it does is it just latches. onto the receptor and it inactivates it, essentially. So, it masks the receptor.

What caffeine does then is race into. your brain. You've got all of this. sleepiness at 9:00 p.m. or 10:00 p.m. You have an espresso cuz you're trying. to power through and finish the report. or, you know, the presentation for your. sort of your pitch for your deck for. your startup company. And that caffeine races in, it latches. onto the adenosine receptors, and blocks the signal of adenosine. So, now your brain was thinking, "I'm. starting to get tired. It's 10:00 p.m.". But now, all of a sudden that signal is.

blocked. And it caffeine is like hitting the mute. button on your television remote. controller. It just muts the signal of. sleepiness. So, now you think, "Well, now I don't feel sleepy anymore." And. here's the danger. that even though well, when the caffeine. is in your system and it's latched onto. the receptors, that adenosine is still. there. It's not going away. In fact, if. anything, during the course of the. caffeine in your system, it continues to. build and build. And now, when the caffeine finally gets.

metabolized and excreted out of your. system, not only do you go back to the. sleepiness that you had many hours. before, it's that plus all of the. adenosine sleepiness that's been. building up during that time in between. So, you get hit with this huge tsunami. wave of sleepiness, and that's what we. call the caffeine crash. So, the one of the issues So, that's. sort of caffeine in terms of how it. works and its timing. Another issue is. that it creates anxiety, just as you.

said. And anxiety is probably one of the. greatest enemies of sleep. It's one of. the principal reasons that underlies. insomnia is a physiological state of. anxiety, that your fight or flight. branch of the nervous system is. ratcheted up. That's what caffeine will. do. It needs to do the opposite for you. to fall asleep. That's why you can have. what we call the tired but wired. phenomenon, where you say, I'm so. desperately tired. I am so tired, but I'm just so wired that I can't fall. asleep. It's because your nervous system. is too amped up. Caffeine will trigger.

that amping up. Then at that point, if you're struggling. to fall asleep because you've got too. much caffeine on board, it is what we. call anxiogenic. So now you start to. worry. And the last thing you need to do when. your head hits the pillow for good sleep. is worry. Because when you start to. worry, you start to ruminate. And when. you ruminate, you catastrophize. And when you catastrophize, you're dead. in the water for the next 2 hours when. it comes to sleep. Because we have this.

sense that, you know, things at night, in the darkness of night, are so much bigger than they are in the. brightness of day. And we start worrying, you know, in this. modern era, we're constantly on. reception. And very rarely do we do reflection. Unfortunately, the only time we we. typically do reflection is when we turn. off the light and our head hits the. pillow. And that is the last time you. want to be doing reflection. So that's. the the second problem with caffeine. It's anxiogenic, and it only makes you,

sort of, almost like the Woody Allen. neurotic of the sleep world. The final part of caffeine is that it's. very good at blocking your deep sleep. So we've done a number of these studies. where we'll give people a standard dose. of caffeine, let's say, 150 mg to 200. mg, which is probably, you know, a cup. and a half of good strong coffee. And then we put you to bed and we look. at the amount of deep sleep. And it will. strip away your deep sleep by about. somewhere between 15 to 30%.

Now, to put that in context, to drop. your deep sleep by 30%, I'd probably. have to age you by about 40 years, 4 0. Or you could do it every night with an. espresso with with dinner. And that's. one of the problems. People will say to. me, "Look, I'm one of those people who I. can have two espressos with dinner and I. fall asleep fine and I stay asleep. So, no harm, no foul." Well, not necessarily. because even if you fall asleep and you. stay asleep, you're not aware of the.

lack of the deep sleep that you're not. getting because of the caffeine. And so, now you wake up the next day and you. think, "Well, I don't remember having a hard time. falling asleep. I don't remember waking. up, but now I'm reaching for two or. three cups of coffee the next morning. rather than my standard one cup of. coffee because I don't feel refreshed. and restored by my sleep because I was. lacking the amount of deep sleep.". And deep sleep, what does that rob us. of? The lack of deep sleep? So, lack of deep sleep deep sleep is. critical for regulating your. cardiovascular system. It's the time. when we do replenish the immune system.

It also regulates your metabolic system, so it controls the hormones such as. insulin that will regulate your blood. sugar and you will become blood sugar. dysregulated without sufficient deep. sleep. Upstairs in the brain, deep sleep. will um strengthen and consolidate and. secure new memories into your brain. They will prevent those memories from. being forgotten. Deep sleep is also the. time when we cleanse the brain of. metabolic toxins, particularly the. toxins that are related to Alzheimer's. disease. So, getting a lack of deep.

sleep is, I would say, a non-trivial. thing um. in that regard. But, I don't want to be also puritanical here. and this is where I'm going to change my. title tune. I am not here to tell anyone how to live. their life. I have no right to tell. anyone how to live their life. I'm just. a scientist. All I want to try and do is gift you the. science and the knowledge of sleep so. that you can make an informed choice.

And after all, and the same is true for. alcohol too and sleep, you know, life is. to be lived to a certain degree. You know, no one wants to be the. healthiest guy in the graveyard. I don't want to be that way, too. I want. to live life just with moderation. The. reason I don't drink. uh caffeine is not because. uh I'm so puritanical I want to be the. poster child of good sleep. I love the. smell of freshly ground coffee in the.

morning. It's a great ritual. It's just. that I've read my genetics and I am one. of the slow caffeine metabolizers. So, you can do these genetic kits online and. they will tell you are you a slow. metabolizer or a fast metabolizer. So, that's the variability. That's why some. people say, "Look, I'm pretty immune to. caffeine." And others will say, "No, I'm. not." Um why do I now favor coffee? I. was actually quite. anti-caffeine. and coffee when I first came out with. the book, just looking at the studies.

But now the data is immensely. compelling. The health benefits. associated with coffee are undeniable. Study after study after study. And we. can put them all together in this big. what we call a meta-analysis study. And. it is so strikingly clear that coffee, drinking coffee, is a good thing for you. from a health perspective. Two things to say about that. The first. is that it's got nothing to do with the.

caffeine. And a lot of people have sort of rightly. challenged me to say, "Look, you say how. problematic sleep can be when you're. drinking too much caffeine. But yet coffee is associated with many. of the same health benefits that sleep. is associated with. But coffee is. supposed to hurt your sleep. How do you. reconcile those two, Matt Walker?". And the answer is very simple. Antioxidants. Because it turns out that the coffee. bean contains a whopping dose of.

antioxidants. Things such as. it's what's other things such as. cafestol, but it's got a bunch of. incredible antioxidants. Probably the. most powerful of them in terms of the. coffee bean is something called. chlorogenic acid. Now, don't worry, it's. not chlorine, it's not chloride, it's. not bleach. Chlorogenic acid is very. different. And what's happened in the modern world. is that we. on we have and struggle with our diet so.

much because we don't eat enough whole. foods, etc. So, what's happened is that. the coffee bean has been now asked to. carry the Herculean weight of all of our. antioxidant needs on its shoulders. And where most people get the majority. of their antioxidants. is by way of drinking coffee. That's why. coffee is associated with so many health. benefits, and it's not the caffeine.

Case in point, if you look at the. studies with decaffeinated coffee, you. get very similar health benefits. Again, it's not the caffeine, it's the. coffee itself. So, the bottom line here is. drink coffee, but I would say the dose. and the timing make the poison. So, try. to limit yourself to about two cups of. coffee, three cups of coffee maximum, because if you look at the health. benefits, by the way, it's a dose it's not a dose response. where it's linear where the more and.

more coffee you drink, the more and more. healthy you become. It peaks at about. two to three, and then actually starts. to go down in the opposite direction for. lots of reasons that we can speak about. So, dose and the timing make the poison when. it comes to coffee. So, you drink decaf? So, I do drink decaf. So, I will drink. coffee just because I love the smell, and I do enjoy the taste of it, but I. drink uh decaffeinated coffee. I would love to drink uh caffeinated. coffee too, cuz I. you know, I I'm sure.

it would be interesting cuz I work out. day and I work out every morning and so. many of the health coaches that I speak. with and health professionals say, "You. know, you should definitely get a shot. of caffeine and it boosts your workout.". And actually the data on that is pretty. clear, too, that. your lifting, for example, in the gym. and your metabolic activity is stronger. when you've had pre-caffeine doses. But it's also stronger when you sleep. But exactly, and that's the problem. So, uh and sleep is. I would argue much more beneficial to.

health and if you're trying to work out. or you're trying to uh be an athlete or. perform, sleep will trump caffeine five ways till. Tuesday. I mean, sleep is probably the. very best legal performance-enhancing. drug that we know of that not enough. athletes are abusing. As you might know, this show is now. sponsored by Airbnb. I can't count how. many times Airbnbs have saved me when. I'm traveling around the world, whether. it's, you know, recently when I went to. the jungle in Bali or whether it's when.

I'm staying here in the UK or going to. business in America. But I can also. think of so many times where I've stayed. in a host's place on Airbnb and I've. been sat there wondering, "Could my. place be an Airbnb as well?" And if it. could be, how much could I earn? It. turns out you could be sitting on an. Airbnb goldmine without even knowing. about it. Maybe you have a a spare room. in your house that friends stay from. time to time. You could Airbnb that. space and make a significant amount of. money instead of letting it stay empty. That in-law, that guest house, that.

annex where your parents sometimes stay, you could Airbnb that and make some. extra income for yourself. Whether you. could just use some extra money to cover. some bills or for something a little bit. more fun, your home might be worth a. little bit more than you think. And you. can find out the answer to that question. by going to airbnb.co.uk/host. One of the other sort of ongoing. stereotypes that I've always wondered if. it was wrong or right or whatever, now I. get to a chance to ask you is about this. culture of sleep medication. So I've got.

some friends who who might have I don't. know prescribed sleep medication but. I've got a lot of friends also that use. what they call sort of natural they. always use the word natural natural. something so it's like natural sleep. tablets. What's your perspective on this culture. of us. humans taking sleep tablets to get them. to feel sleepy and go off to sleep at. night? Usually when people ask me that question. personally I the first thing I ask them. is why is it that you think you're not. able to sleep?

And try to reverse engineer the question. from there before we even start thinking. about sticking band-aids on wounds I. firstly want to ask what's causing the. infection because we can keep bandaging. it for all we like but if it keeps. festering it's probably not going to go. away anytime soon. Is it a problem to keep bandaging it? It is a problem. Right now we don't. typically advocate sleeping pills as the. first line defense agent against or for. insomnia as a treatment. In fact in 2016.

the American and again this is me simply. describing the science. This is me being. descriptive of the science not. prescriptive in in terms of medicine cuz. I'm not a medical doctor. Um. but in 2016 the American College of. Physicians they had a expert panel who. surveyed all of the literature on. classic sleeping pills and what they. suggested was that sleeping pills must. no longer be the first line treatment.

for insomnia it has to be cognitive. behavioral therapy for insomnia or what. we call CBT-I which is a psychological. intervention that we can speak about. But their recommendation was that they. found. I think their wording was um small and. of questionable clinical importance in. terms of the benefits of sleeping pills. Now. there is a time and a place. for in clinical medicine for sleeping. pills, but usually as an adjunct in. combination with cognitive behavioral.

therapy. They are not advocated for long-term. use, but so they usually advocated for. short-term use, weeks. Most people have been on them for months. if not years, these classic sleeping. pills, and that's a problem. because those sleeping pills are in a. class of drugs that we call the sedative. hypnotics. And sedation is not sleep. For sub- subset of some people, there. are some of these {quote} {unquote}. sleep supplements that may benefit, but.

overall, the studies are very clear. None of them are efficacious. And when you think about it, it makes. sense. You know, if there was some cheap sleep. supplement that you could buy on Amazon. that was the Shangri-La of good sleep, that was this miracle sleep drug, don't you think that a pharmaceutical. company would have patented it 20 years. ago and be making billions of dollars. from it? You know, that alone tells you. all that you need to know about, you. know, these natural sleep supplements.

Cognitive behavioral therapy for. insomnia though. Yeah. seems to be the kind of the front line. of. prescribed defense against a lack of. sleep insomnia conditions. What exactly. is that therapy aiming to do? What like. what does it do for for somebody? Great question. So, in some ways, the. the title um tries to suggest what it. what it does, but not particularly well, perhaps. So, it focuses on cognitive. aspects, and it focuses on behavioral.

aspects. So, for the cognitive aspects, when we. do cognitive behavioral therapy working. with the patient, we'll try to focus on. thoughts and beliefs and ideas around. sleep. Do they have anxiety around the. bedroom? Most of them do. I can't sleep. Because I can't sleep. So, every time I. walk into the bedroom, my bed is the. enemy. And I look at the bedroom and I. look at the bed, and I just know that. that means I'm going to have a bad night. of sleep. So, what's happened is that at. that point, your sleep controls you.

And you've lost all confidence in your. ability to sleep. And we need to course. correct that. So, one of the things we. do in cognitive behavioral therapy is. that we lower that anxiety. And we say, "Look, everyone has a bad night of. sleep, even a bad couple of nights of. sleep. In fact, I will tell you, I don't. sleep perfectly well all the time, too. I've had at least two very severe bouts. of insomnia in my life. We all have a bad night of sleep. It. doesn't mean that tomorrow you're going.

to wake up with depression or. Alzheimer's disease. Don't worry, you're. not going to get cancer, you know, tomorrow, just because you've had a bad. night of sleep. So, we start to change. people's misbeliefs about sleep. And we. try to get them back from being. catastrophic about this idea of my not. sleeping. So, we That's the cognitive aspect. We. start to lower their anxiety around the. bed and and the bedroom. We start to try. to build confidence back. We start to. reduce their expectations about, you.

know, what is reasonable sleep? Well, right now you're getting 4 or 5 hours of. sleep, and we can do better. But, don't. start thinking that you need to get 8. hours of sleep straight out the box. Let's just manage it. That's just because it's going to stress. you out, right? It's only going to make my sleep worse. Right. Okay. You know, when you're struggling with. sleep in the middle of the night and. you're wide awake, you're laying in bed and you're. thinking, "Oh my god, I've got 5 hours. left before I've got to go to work.". It's terri- It's the last, you know, it's a little bit like trying to. remember someone's name. The harder you. try, the further you push it away.

So, would you say in that What What do I. do in that situation? You It's 2:00 a.m. in the morning, you've got to be up at. 7:00, there's a flight you're getting. on, say, whatever. Yeah. What should one do? Cuz. from what I was reading in chapter 14, I. was I was hearing that maybe I should. get out of bed. Or not just sit there and ruminate. You know, into the early hours of the. morning. Or do I stay in bed and do. something? What does one do? The prototypical recommendation is that. after about 30 minutes of time awake, you should get out of your bed and you.

should just go to a different room and. do something like, you know, read a book. or listen to a podcast. Don't eat cuz it. then trains your brain to wake up to do. that. Don't start working or getting in. front of a computer screen, you know. I. said listen to a podcast, sure, you. know, just make sure your phone's in you. know, you don't start scrolling anymore. than that. But you can do relaxing. things, stretch, meditate. The reason is because if you start to. spend a lot of time awake in your bed, your brain is an incredibly associative.

device. And very quickly, it will start. to learn that this thing called your bed. is this place where I'm always awake. And therefore, you start to learn. through this. repeated loop of behavior that I'm. always going to be wide awake in bed. And we need to break that association, and that's why we say get out of bed. after about 30 minutes, cuz you're just. training your brain to think that this. thing called my bed is the place where. I'm never asleep. And we want to break. that. And only return to bed when you're. sleepy, and there's no time limit for. that. And that way, gradually, it's much.

better because you will relearn the. association that your bed, just as when. you were young, was guaranteed that your. bed is this place where you will always. be asleep. The problem with that is many people. don't want, you know, it's the middle of. the night, it's dark, it's cold. I I'm. not I'm just not going to get out of. bed. So, what's your other what what. else have you got in your toolbox, Matt? Um. at that point, I would say, "Okay, that's reasonable.". The first thing I would suggest is. meditation. You know, I am a hard-nosed scientist,

and when I was researching that the. book, I was, you know, I just thought this. sounds all a bit woo-woo and you know, I. I live and work in Berkeley, California, which is kind of, you know, the free. speech, you know, flower power movement, San Francisco, flowers in your hair. business. I just thought this is all a. bit, you know, holding hands and singing Kumbaya. This. is This is not for me, this this. meditation stuff. I couldn't get away. from the strength of the data. It was. immensely powerful regarding sleep and.

its benefits on insomnia and sleep. So, I started meditating and now I meditate. for 10 minutes before bed every single. night and I've been doing that for about. 4 years. So, I would say if even if it's. in the middle of the night and if I wake. up in the middle of the night, I'll. start try to walk myself through a. meditation. Um. You You referenced there. listening to podcasts, etc., etc. You. know, doing something else to stimulate. the brain. I when I go to bed, I have to.

have something playing. I say have to. I. shouldn't be that definitive. I like to. have something playing, some kind of. sound or noise, whatever. And much to my. partner's dismay, my. content of preference is. serial killer. podcasts or documentaries or just like. something which is really going to grab. hold of my brain and focus me. So, something like It has to be really. interesting to me for me to be able to. focus on it. My partner is the opposite.

again. She likes um. silence. Why do I listen to serial killers? It's different for different people's. constitutions, you know, and. psychologies. Uh and you know, I can pathologize you. all you like if if you would wish me to, but I would say it. what's fundamentally going on here with. meditation and I'll come back to an. alternative, too, but the reason why. some meditation apps as well have now. started to do what's called sleep.

stories, which in some ways is what. you're doing a version of with your. podcast, is hark back to when we were kids. You. know, for many parents, they would just read a. book to the kid. You know, the. children's books, good night books. Because you would read the child to. sleep. And for some reason, we as we developed into adults, we. thought, well, we no longer benefit from. having a story read to us to help us. sleep. No, it's not true. We.

we benefit hugely. In fact, the the. meditation company Calm, you know, was. saved by the introduction of sleep. stories into their app. They were doing. pretty well as a meditation app, but. then they started to do sleep stories. and it became a unicorn company um in. terms of its valuation. It broke a. billion dollars. And it was on the. the back of sleep stories. And what they realized is that people. were self-medicating their insomnia by. way of meditation. So, they latched onto that and then they.

found that these stories, sleep stories, were great. And you've got now wonderful. people, people who you've interviewed on. the show. So, what you're doing and what. those sleep stories are doing and what. meditation is doing, it's all the same. thing, which is that it is taking your mind off. itself. Because when you are struggling to sleep. or you've woken up in the middle of the. night, what you don't want to be doing is. focusing on either what you. what you What did I do today? What did I.

not do today? What did I do poorly? Oh. my goodness, what have I still got to do. tomorrow? And at that point, things are. just a disaster. You're wide awake. What all of the things that we've just. discussed do is they take your mind off. itself. And at that point, then you start to. allow sleep to come back naturally. That's why one of the other suggestions. is take yourself for a mental walk. So, don't count sheep, by the way, that.

doesn't work. A colleague of mine at UC. Berkeley did the study. Actually, takes. you longer to fall asleep if you're. counting uh sheep. What she found that. the Dr. Allison Harvey was that if you. just close your eyes and you think about. a walk that you take frequently, let's. say it's a walk with the dog, and you think about it in high-fidelity. detail. So, I close my eyes, I go out. the door, take a left down the steps, then I'm going to go up the street, I. take the first left past that pine tree. That's the level of detail. If you just. walk yourself on that mental walk, sure.

enough, people fall asleep in about 50%. less time, half the time it takes. This is the thing with sleep stories and. also my serial killer documentaries or. serial killer podcasts that I listen to. Detail. Exactly. You get even I've listened to. Calm's sleep stories before, and the. attention to detail in the sort of. descriptive nature of what they're. saying is so apparent. They'll say. things like, "The cold, wet window sill saw the. raindrops like.

um tapping against it one by one by one. by one." And that sounds very similar to. my serial killer documentaries when I. hear about the serial killer coming in. through the window. Yeah. Yeah. Yeah. At night time. Um. and I wondered why the descriptive. nature of it, the detail matters for. dozing us off. And because it prevent I mean, you've. got limited bandwidth in terms of. cognitive capacity. Right. And if you're consumed and you saturate. your bandwidth with that level of. detail, it's very hard for any of these. other things called our worries and our.

anxieties to start entering into our. mind. The other thing I would note, by. the way, though, is. if you are if none of these things are. working for you, if the fictional notion. of serial killing is not working for. you, if meditation is not working for. you, if going on a mental walk is not. working for you, this is the final suggestion I have. If. you're lying there awake, firstly, by. the way, if you're struggling with. sleep, remove all clock faces from your. bedroom. It's one of the best pieces of. advice I can give you.

Knowing what time of night it is is no. favor. So, knowing now that it's 3:23 a.m. in. the morning and I'm still struggling to. fall asleep, and then I look back at the. clock and it's now 4:03 a.m. and I've. still been awake, and now it's 4:27 and. I've got to wake up at 6:30 a.m. Knowing. that. has no utility for you. Remove all clock. faces from your bedroom. It is a gift. But, coming back to the final.

suggestion, if you don't want to get out. of bed, if you don't want to listen to a. podcast, the final thing I would say is just. accept and say, "Look, it's okay. Tonight is not my night. It is not the. worst thing in the world. And instead of. trying to sleep, all I'm going to do. here is lie in bed, and I'm just going to rest.". Because wouldn't it be lovely if someone. came to you in the middle of your work. day, you're just stressed and someone said, "By the way, just come into this room.

There's a There's a bed here. Just lie. down and just rest for an hour.". Wouldn't it be lovely? Just have a good. old rest for an an hour. Just rest. there. And I would say that if you can't sleep, just lie in bed, stop worrying about. sleep and not being able to get it, stop. worrying about the next day, just lie in. there and enjoy a nice good old rest. And by the way, usually what happens is. that after you start thinking, "Okay, I'm going to rest," the next thing you. remember is the alarm clock going off at.

6:30 because finally you stopped trying. and sleep happened. So, yeah. Of course. You know, prolonged one of. the things I've also I wonder if this is. a if I'm wrong about this is I sometimes. thought that, you know, I could go. Monday to Friday and kind of sacrifice. my sleep. This was specifically when I. was really in the height of like running. big businesses, etc. Um and then on the weekend I'll just. make up for it. So I thought, you know, I could go. Monday to Friday, I'll sleep maybe. sometimes 2 hours a night, 3 hours a. night, whatever. Then Saturday, you. know, I'll just do a, you know, 11-hour.

sleeping and I'll just make up for it. Yeah. Is that a good strategy? The delightful laughter at the end of. your sentence that uh. I think probably tells you the answer. that you know. Um. unfortunately, sleep doesn't work like. that. It would be nice if it did. Sleep. is not like the bank. In other words, you can't accumulate a debt. as you were doing during the week and. then hope to try and pay it off.

at the weekend. Um. So for example, let me take an extreme. version of that experiment. Let me take. you tonight. I'm going to deprive you of. sleep for an entire night for, let's. say, 8 hours of sleep. And then tomorrow. night I'm going to give you all of the. recovery sleep that you want, as much as. you wish for. And then the next night. you can have all of the recovery sleep. that you want. And even on the third. night, will you sleep longer that first. recovery night after a night of no. sleep? Absolutely, you will sleep.

longer. But across those three or four recovery. nights of sleep, will you get back all. of the sleep that you lost? Not even. close. You'll maybe only sleep back. about four, four and a half of the 8. hours that you lost. In other words, by. that stage, you are four or three and a. half hours in overdraft on your sleep. bank account. You went into debt and you. only paid about 50% of it back. So. what's happening with you during the. week is that you're accumulating this.

debt, you know, of maybe 10 hours. You're. short-changing, you're only sleeping. like 6 hours a night for the five nights. during the week. And then you binge on. sleep and you try to maybe sleep 10. hours or 11 hours, that's only two or. three extra hours. So, sum total that's. only four to six, you know, hours of. made-up sleep. relative to the 10 hours of debt. So, what happens is that that next week, you. now carry forward four hours of your.

debt. And then next weekend, you try to sleep. it back, but you're still four hours. lost. So, now you've got eight hours of. net debt. In other words, what it. develops is into a compounding interest. on a loan. It just starts to escalate. ballistically across weeks, across. years, and across the lifespan. And then what happens in terms of. health outcomes? So, say that I did that. for a couple of years. Say that I. sustained that pattern of, you know, depriving myself of sleep throughout the. week, maybe catch up on Saturday, Yeah. depriving myself again the next week,

catch up on Sunday, deprive myself the. next week, and I did that pattern for. multiple years. What would What would be. the health implications? So, you can describe them short, mid, and long-term. The first thing I would say though is. that the elastic band of sleep. deprivation will stretch only so far. before it snaps. The short-term, you know, probably the most immediate. short-term consequence is that you are. popped out in a driving-related. accident, drowsy-related accident.

Because drowsy-related accidents are. non-trivial. They make up a large. proportion of accidents on our streets. in terms of human error-full driving. When you say popped out. out of the gene pool. Okay. So, what happens is that when you. are under-slept, you're at the wheel and. you start to have what we call. microsleeps, where your eyelid will partially close. Now, you are not aware of it. You have. no awareness of it whatsoever. And in. fact, parts of your brain seem as though.

they're almost falling asleep. Like. you're having this microsleep, and it. lasts for about a second or two seconds. Now, if you're on the motorway and. you're traveling at 70 mph. and you have a 2-second microsleep, that's enough time for you to drift from. one lane into the next. If you're just. in a two on a two-lane, you know, sort. of. backstreet. where there's oncoming traffic in the. other direction. and you're traveling at 40 mph and you. drift halfway into that lane,

that's oncoming traffic. So, in other words, if you have a microsleep. at 60 or 70 mph, at that point there's a. 2-ton missile traveling at 60 mph and no. one's in control. And that may be the last microsleep that. you ever have in your life. Obviously, all the other things you've. mentioned would be implications, things. like performance drop, and sort of. memory, relationships, libido would all. drop off. So, I wouldn't be having as. much sex, I wouldn't you wouldn't have. all those things. Then mid-term. So, mid-term, then you're going to. escalate those things into more disease.

state. So, for example, if I were to. take an individual and people have done. these studies, not not we, but um where. you limit them to let's say 4 or 5 hours. of sleep for 1 week, your levels of blood sugar are disrupted. so significantly that your doctor at the. end of that 1 week would classify you as. being pre-diabetic. So, that's you could almost argue that. short-term, not mid-term. Mhm. Yeah. Um you know, one if you're a male and I. limit you to 4 or 5 hours of sleep, a.

healthy young male, um for 1 week, I will drop your levels. of testosterone to that of someone who. is 10 years older than you. So, I can. age you by a decade just by short. sleeping you for 1 week. We see. equivalent impairments in female. reproductive health in estrogen, luteinizing hormone, and. follicle-stimulating hormone. Um so, it's both men and women. Your blood pressure will start to creep. up, your systolic blood pressure in. particular will creep up. Your heart.

rate in terms of its um contraction. rate. In other words, your the the speed. of your heart starts to increase. The progression into obesity, diabetes, cardiovascular disease, mental health. issues, anxiety, depression, suicidality, all of these things, immune compromise, infection. All of those things can be termed, you. know, will be mid-term. Now, all of. those things have a longer-term tail to. them, which is this thing called. premature mortality. So, using that.

sweet spot of 7 to 9 hours of sleep, you. can argue that there's a simple truth on. the basis of the data. The shorter your. sleep, the shorter your life. That short. sleep will predict or cause mortality. Is that supported by the by data? That's supported by data, yeah. Now, there's an interesting change there, which is once you get past about 9 or 10. hours, your mortality risk doesn't just. keep going down and down. It will hook. back up again, as if almost too much. sleep is a bad thing, and we can explain. why that is the case as well, and why.

it's probably not quite as simple as. that. But, the final long-term. consequence that I would say is. Alzheimer's disease. You know, the two. most feared diseases in developed. nations are cancer and Alzheimer's. disease. Both of them have links to. insufficient sleep, many of them causal. And this relationship between sleep and. Alzheimer's disease, this is where we. actually do, I'd probably say almost 50%. of the work that I do at my sleep center. is focused on sleep and Alzheimer's. disease. And there, the data is stunning, I would. say.

At this stage, insufficient sleep seems. to be one of the more or one of the most. significant lifestyle factors that can. develop or dictate the development of. Alzheimer's disease later in life. Now, that's a lifestyle factor. There are. other genetic factors, but certainly we. now know that it's not just that. insufficient sleep. predicts a greater amount of Alzheimer's. pathology in your brain. So, for. example, people who on average are.

sleeping 6 hours or less have a far. higher magnitude of amyloid of beta. amyloid, which is the sticky toxic. protein related to Alzheimer's disease, and another protein called tau protein. These are the two protein culprits of. Alzheimer's. Both of those are escalate. the less and less sleep that you have. Now, that's just associational. We also. know, by the way, that two sleep. disorders, insomnia and sleep apnea, heavy snoring, both of those are. associated with a marked increased risk. of your Alzheimer's disease of.

Alzheimer's disease later in life. That's simply associational. That. doesn't prove causality, but we now have. the causal evidence both in animal. models and in human models. If I deprive. a human being of sleep for single night, or I even just deprive you of deep sleep. for a single night, the next day we can. see an immediate increase in these. Alzheimer's disease-related proteins. circulating in your bloodstream, circulating in what we call a. cerebrospinal fluid that bathes the. brain, and using special brain scans, we.

can even measure it within the brain. itself. So, these are causal manipulations. It's. not associational. I manipulate this. thing called sleep, and the consequence. is that I manipulate your Alzheimer's. disease proteins. That's correlation going to causation. Then the question is, well, mechanism. What is it about sleep when you get it. that is de-escalating Alzheimer's. disease risk? In other words, when you don't get it, what why would it increase your. Alzheimer's risk? And this is a stunning.

discovery made by a scientist called. Maiken Nedergaard at the University of. Rochester here in America. And she found three things. First, studying mice and rats, she found that. the brain has a cleansing system. Now, we didn't used to think that your brain. had a cleansing system. Your body had. one, and everyone knows what it's. called. It's called the lymphatic. system. Um we didn't think the brain had one, but she discovered that the brain has. one. It's called the glymphatic system,

named after these glial cells that make. it up. The second thing that she discovered is. that that cleansing system within the. brain is not always switched on in high. flow volume across the 24-hour period. It was expressly during sleep and. particularly during deep non-REM sleep. when that sort of sewage system was put. into overdrive and washed away all of. this detritus that built up during the. day. And the final thing that she discovered,

and this is why it's related to. Alzheimer's disease, is that two of the. metabolic byproducts that build up. during the day in our brain. are beta amyloid and tau protein, the two bad actors in Alzheimer's. disease. So, in other words, what she discovered. is a system of, you know, good night. sleep clean. That sleep is a power. cleanse for the brain. And if you're not getting your sleep. every night, you know, it doesn't mean. that you're going to get Alzheimer's. disease next week. It doesn't mean that. you're going to get Alzheimer's disease, you know, in a year's time.

But night after night, once again, it's. like compounding interest on a loan. And that's why we now believe through. this causal mechanism that insufficient. sleep is a risk factor for Alzheimer's. disease. Lots of people will say to me, "Look, there are these individuals in society. who claim that they, you know, didn't. very much sleep, who didn't sleep a. lot." You know, Margaret Thatcher is. often quoted me uh quoted to me about. that. You know, um. uh Ronald Reagan was apparently another.

short sleeper. I don't think it's coincidental that. both Thatcher and Reagan went on to die. of the unfortunate disease of. Alzheimer's. I'm I'm sold. Sleep is important, I get it. I'm sold. How do I. My question is, what are the things that. in the modern society are standing in. the way of sleep? We've touched on some.

of them loosely, but some of the like. big obvious things, the things that you. would suggest doing, very actionable. things we could do straight away to. improve our chances of having that. healthy. deep sleep that we need to be optimal in. every regard of our health and. performance. There's probably, I think, five standard. tips, what we call sort of sleep. hygiene, that you can do. And then I'll. come on to maybe just some. unconventional tips that we've sort of. touched on. And we've spoken about many. of these. The first thing I would. recommend people to do, and this is why.

when some people say, "How What about. this new sleep supplement?" Or, you. know, it's it's 40 quid for this bottle. of these sleep. new sleep natural medications, so I'm. going to give it a try. I would say, try. these tried-and-true things first before. you spend your money on supplements. The. first thing is regularity. Go to bed at the same time and wake up. at the same time, no matter whether it's. the weekday or the weekend. Your brain expects regularity. It. thrives best under conditions of. regularity. When you give it regularity,

you can improve the quantity and the. quality of your sleep. The second thing is get some darkness at. night. As I said, we don't get enough. darkness in the modern world. And so, the trick I would offer, and I. don't use it I don't like the word hack, but the sort of suggestion would be in. the last hour before bed, try this experiment for everyone. listening for the next week, dim down half of the lights or switch. off half of the lights, or even a.

three-quarters of the lights in your. home in the last hour before bed. All of the lights in every room? In all of the rooms, you know, switch. off almost all of the light. Now, I'm. not suggesting be unsafe and walk around. in the darkness in the last hour. That's. not what I'm saying. Just dimmed out, you know, switch off half of the lights. You will be surprised at how sleepy that. darkness will make you feel. And it's. also an incredible behavioral trigger. to.

signal to your brain that it is time for. sleep, that darkness is around me. That's the second tip is darkness. The. third tip tip is temperature. Most people sleep in an ambient bedroom. temperature that is too high. And you need to aim for a bedroom. temperature of about 18 18 and 1/2. degrees Celsius or around about 65 to 68. degrees Fahrenheit if I'm I'm probably. butchering the the mathematics there on. that, but um. you need to get cool. Now, you can wear.

thick socks, you can have a hot water. bottle. That's fine, but the ambient. needs to be cold. Because you need to drop your core body. temperature and your brain temperature. by about 1 degree Celsius to fall asleep. and stay asleep. And it's the reason that you will always. find it easier to fall asleep in a room. that's too cold than too hot. So, make your bedroom cold. Make it dark. like cave. The the fourth question would be sort of. what we've or fourth suggestion would be.

walk it out and we've spoken about this, the 30-minute rule, you know, get up, do. something different or meditate, you know, don't lie in bed awake for too. long. Then the final two things we've. spoken about Well, we spoke about. caffeine. We haven't spoken about alcohol, but let. me just say as the kind of headline of. it, alcohol is not a sleep aid. Many. people use it as a sleep aid. It is not. your friend. Alcohol again is a. sedative, so it knocks you out. The. second is that it fragments your sleep. So, you wake up, your sleep is littered.

with all of these small awakenings. Most. of them you don't remember cuz it's too. brief, but it makes for miserable lousy. quality sleep. And the final thing is. that it alcohol is very good at blocking. your REM sleep or your dream sleep, which we know is critical for many other. functions as well. So, alcohol's not. your friend. That's the sort of the. final tip. Again, you know, just every. if you're with friends, have a glass of. red wine. Just know, okay, my sleep's. not going to be great that night. Yeah, okay. I mean, that's you know, I'm not yeah,

I'm. whatever it's just, you know, live life. Of course, yeah. I'm not saying that. I I was I was thinking there about the. other sort of behavioral things that we. do that harm our sleep as well. We. talked about coffee earlier on, avoiding. that. It's weird that people drink it. after dessert in the evenings. I've. never understood that. Guess that's an. old tradition. Um but the other thing. obviously that the modern generation are. even more susceptible to is to. have a quick TikTok. Look at the social. media account or something. Now, I. thought, you know, there's a lot of.

different products out there that are. trying to help with the the the light. that comes from these screens that I. think is the cause of what's keeping us. awake. But there's this little button. called dark mode on my iPad. Oh, there's. also one called night shift. So, if I. just pop that on, Bob's your uncle. And this and I can crack on with my. screen time. True or false? Partly true. Oh, good. Okay, partly. So, I can just. pop that on night mode and dark mode and. then I can carry on using my iPad.

Partly true. So, it turns out that the blue light. from screens does have an impact on. sleep. There's a great study done by. Harvard Medical School by some. colleagues there. And they showed that. reading for an hour on an iPad just. before bed relative to just reading a. book in dim light, firstly, it delayed. the time with which people fell asleep. So, it took them a lot longer to fall. asleep. Second, it reduced the total. amount of sleep that they had. Third, it. decreased a sleep-related hormone called.

melatonin. It delayed the release of. that melatonin and it reduced the amount. of melatonin. And finally, it reduced. the amount of rapid eye movement sleep. So, it had. Significantly. Significantly. point, how how significantly? So, it delayed the release by about. somewhere between 90 minutes to 2 hours. across the individuals. So, in other. words, your brain wasn't So, what. melatonin does, it's a it's called the. hormone of darkness or the vampire. hormone just because not. cuz it makes you want to bite into. people's necks, but because it signals.

to your brain that it's night time, that. it's darkness. And so, your brain needs the signal of. melatonin for it to understand when is. it dark. In other words, it needs to. understand by way of melatonin when it. is time to fall asleep. And when you're bathed in electric light. at night, and especially when you're. getting blue light from these devices, your brain is fooled into thinking it's. still daytime. And when there is light. emitting through your retina, coming. into your brain, it signals to a part of.

your brain to hit the brakes on. melatonin, and your brain will not. release melatonin. So, what was. happening with this iPad reading is that. you were artificially telling the brain. it's still daytime, and the brakes on. melatonin was still shut on. And so, melatonin was not starting to be. released until much later. And what was it also interesting about. this study, by the way, is that when. they stopped the iPad reading, the sleep. disrupted pattern continued for several. days later. In other words, it was. almost like a drug that it had a wash.

out period, that it was a blast radius. to it. Now, there's been some great work by a. wonderful sleep scientist in Australia, Michael Gradisar, and he has added to. this story, and he said it's not just. the blue light. These devices, the. principal function of these devices is. that they are attention capture devices. Just like you said, "I'm just going to. have a wee little Tik Tok before bed.". They are in the attention economy. And all they care about is capturing.

your attention for a current currency, and they make a lot of money from it. What that attention does is that it. stimulates your brain. And when your. brain is stimulated, it's very difficult. for you to fall asleep, and it creates. what we call sleep procrastination. Where you're lying in bed, and you could. be perfectly sleepy, and you could fall. asleep right now. But then you sort of check social media, and you think, "Oh, I'll just shoot that. last email." And then I'll order that. last thing on sort of, you know, Amazon. Uh and then you get a text back from.

your friend, and you start texting them. And and then you look up, and it's now. an hour later, and you're an hour. deficient on sleep. So, it's the. activation of your cerebral cortex by. these devices that is perhaps the more. harmful aspect of them regarding your. sleep. Now, here again, I don't want to be. finger-wagging. You know, the genie of. technology is out the bottle, and it's. not going back in anytime soon. There's. nothing that I'm going to say as a sleep. researcher that's going to change that.

I don't take my phone into my bedroom. I put my phone uh out in the kitchen. I. don't uh see it until morning. But lots. of people do, and fair enough. But. there's another rule uh that I've stolen. from another friend uh called Michael. Grandner, who's uh here in America at. the university. um of uh Tucson in Arizona. He has this. great rule regarding technology, and. it's the following, that if you really. must take your phone into your bedroom, you can only use it.

standing up. And what you'll find is that after about. 6 or 7 minutes standing up, you think, "Ah, I'm just going to I'm just going to. sit down on the bed." And at that point, as soon as your backside hits the bed, you're done. You've got to put the phone. away. I think it's a great rule of thumb. if uh if you need to take technology in. the bedroom. Um. I'm going to apply that. The other thing. I wanted to ask was about sleep and. weight loss. Had a lot of health experts on this. podcast recently, but none of them have. really talked to me about the role that. sleep or sleep deprivation plays in.

weight. Is there a relationship? It's probably one of the most. well-defined relationships that we know. in all of sleep science. And it is at least a three-part story. So, the first emerging evidence came in. terms of um hormones. So, there are what we call. appetite-regulating hormones, and the. two principal ones of concern here are. something called leptin and ghrelin.

Now, leptin, when it's released, will. signal to your brain that you're. satisfied with your food, you are. satiated, and you are no longer hungry. Ghrelin does the opposite. When ghrelin. is released, it says, "No, you're not. satisfied with your food. You are not. full. You still want to eat more. You. are still hungry.". And some of the first studies they. started to do uh just limit people, restrict people's sleep to 6 hours or 5. hours or 4 hours, and what they found.

was that um there was. firstly, that signal leptin that says, "No, you're satisfied with your food. You don't want to eat any more. You're. full.". That signal of fullness, satiation, was. decreased by 18%. If that wasn't bad enough, ghrelin, which is the hunger hormone, that leaped. up by 28%. Overall hunger levels rose by about uh.

26%. So, firstly, you are It's almost like. double jeopardy that you are getting. punished twice for the same crime of not. sleeping enough. Once by losing the. signal of, "I'm full. I I don't want to eat any more. And once. again, for the no, I'm much more hungry. and I'm just going to overeat, which is. ghrelin. So, what that produces is a profile of. increased eating. So, on average,

underslept individuals started to eat in. those studies about 3 to 400. extra calories at each sit at each. sitting by way of insufficient sleep. Then, what they discovered is that it's. not just. that you want to eat more, it's what it. is that you have a craving for when you. are underslept. And this is the problem. What they found. is that when you are underslept, you eat. more of everything, but you especially. eat more of these heavy-hitting starchy.

carbohydrates, bread, pasta, pizza. The The next thing that you started to. eat have a preference for was simple. sugary foods, sweets and chocolate. And. then finally, you started to crave very. salty food. And high sodium food intake. will increase your blood pressure. So, that was the first of the the three. mechanisms. Then, we did a study where. we said, perhaps it's not just the. circulating hormones in the body, the.

brain is the ultimate arbiter of your. food decisions. So, what's going on in. the brain? So, we took a group of. perfectly healthy individuals and we put. them through the experiment twice, once. when they'd had a full 8 hours of sleep. and once when we deprived them of. And then the next day, we placed them. inside an MRI scanner and we showed them. images of lots of different foods that. range from being sort of, you know, very. healthy to being very unhealthy and sort. of ice cream and, you know, chocolate. and pizza and things to leafy salads and.

nuts and greens and vegetables. And we asked them to rate how much they. wanted that food for each item. Now, we. we something a bit sort of dastardly to. make it more ecologically correct so. that they weren't just saying, "Okay, they probably think I should probably. say that's healthy." We said, "We're. going to randomly select one of these. images, these food images that you see, and after you get out the brain scanner, we're going to give you that food, and. we're going to politely ask you to eat. it all.". So, it made it a bit more realistic so.

that choices were more, you know, as. much as that we could. So, what we found is that when they were. sleep deprived, the deep hedonic centers. of the emotional centers of the brain, these desire centers, these reward. centers, uh they ramped up in their activity in. response to these highly desirable, highly unhealthy foods. So, these more basic sort of, you know, guttural parts of the brain, as it were, um these reward centers were lighting up.

much more strongly when you're sleep. deprived. Worse still, the impulse. control regions in the front of the. brain, what we call the prefrontal. cortex, they were shut down. They were. taken offline. So, as a consequence, you lost your. impulse control, and that's why you. start to then say, you know, when I'm. sleep deprived at the food sort of. buffet, I'm not I'm not going to do salad. I'm. just going to. that pizza looks awful good, or that. pasta with the cream I'm just going to. go into that all go. So,

so you're it's what we call a pattern in. terms of brain activity uh in. neuroscience of hedonic eating that your. brain goes into this hedonic desire. profile. So, now we understood it's not. just hormones in the body, it's also. changes in the brain. Then came the finding that there's. another chemical in the body that's. responsible. And this comes on to cannabis. When people um. uh when people when people that you may.

know have smoked uh cannabis, they'll. often say, "I get. viciously hungry. I get the munchies. I. get really hungry. That's no coincidence. because cannabis will stimulate. appetite. Now, we all have naturally. occurring cannabis compounds in our. brain and our bodies. They are called. endocannabinoids. Endo meaning comes from inside us. Um whereas the cannabis that comes. externally when you sort of smoke it or. um take edibles.

So, endocannabinoids do many things for the. brain and the body, but one of the. things that they do is control your. appetite and your hunger. And what we. found is that when you sleep deprived. individuals, these naturally occurring. endocannabinoids rocketed up by over. 20%. Cranking up people's appetite. Mhm. And so, these three ways lead you to start. packing on, you know, when insufficient. sleep is occurring, when sleep gets.

short, your waistline typically starts. to expand. And we now understand the reasons. If. that wasn't bad enough, It is bad enough. The final Yeah, I know. Yeah. Can you. just stop, Matthew? Honestly, I really. uh the the last thing that we discovered. is that. let's say that you're trying to be. really careful and you're trying to diet. and you're trying to lose weight. If you're not getting sufficient sleep, then 60% of all of the weight that you. lose will come from lean muscle mass.

Oh god, no. And not fat. Not the muscle. I know exactly. So, in other words, when. you are dieting but you are under-slept, you lose what you want to keep, which is. muscle, and you keep what you want to lose, which is fat. So, again, it's. I'm sold. not an ideal situation. My last question for you, in fact, was. of all the subject matter we've talked. about, what is the most interesting thing we've. missed in your view? The thing that you.

think is most pertinent or interesting. or significant or that perks people up. or sits them on the end of their chair. when you discuss it? I think the only other area that. fascinates people even more than sleep. is dreaming. Mhm. So, dreaming above and beyond the stage. of which it comes from, which is. principally called rapid eye movement. sleep or dream sleep, REM sleep provides a set of.

physiological and. benefits, but dreaming we've now. discovered, even above and beyond that, provides benefits. And it provides at. least two benefits. The first is. creativity. I was telling you that. during deep sleep you cement individual. memories. You grab memories and you. shift them from a short-term storage. reservoir to a long-term storage. reservoir and you strengthen the circuit. of those memories. So, you future-proof. information. But, that's individual. memories. What we discovered is that. sleep is much more intelligent than you.

ever thought possible. That it's during. REM sleep, and particularly during. dreaming, that we take all of the. individual pieces of information that. we've been learning and we start. interconnecting them and associating. them with all of our back catalog of. stored information. And so, what dream sleep, one of the. functions of dream sleep, is to. cross-link. and associate new memories together. So, you wake up the next day having after. dream sleep with a revised mind web of.

associations and those are capable of. divining solutions to previously. impenetrable problems. So, think of dreaming as. it's almost like informational alchemy. That you start to fuse things together. that shouldn't normally go together. But, when they do, they cause marked. advances in your thinking, in your. productivity, in your ingenuity. And in that way, you go to sleep with. the pieces of the jigsaw, but you wake up with the puzzle.

complete. And I would argue that that's. the difference between knowledge, which. is remembering the individual pieces, and wisdom, which is knowing what it all means when. you fit them together. That's one of the. functions of dreaming. It's the reason, by the way, that you've never been told. to stay awake on a problem. Yeah. Um. The other function of dreaming that we. know of is that dreaming provides a form. of emotional first aid. That we've We've done a lot of work and.

we came up with a a theory that was. called dreaming as overnight therapy. And what we've discovered is that when. we go into dream sleep, particularly. based on its neurochemical profile and. its physiological anatomy of the brain, um the dreaming brain will take. difficult, painful experiences, sometimes traumatic experiences, and it will essentially strip away the. bitter emotional rind from the. informational orange. So, let's take a. step back. What makes a memory. emotional? What makes a memory emotional.

is that at the time of the experience, that experience triggered a strong. visceral reaction. And that visceral. reaction is useful to the brain, and it. wraps that experience in this blanket of. what we call emotion. It red flags it. and prioritizes it in the brain. So, now. you've created a memory of an emotional. event. In other words, you've created an. emotional memory. But what dream sleep does is then it. takes that useful emotional memory and. it will detox the emotion from the.

memory. It strips the bitter emotional. rind from the informational orange. Mhm. It's almost And that's why we called it. overnight therapy. So, that the next day. you come back, and now you feel better. about those experiences. So, you have a memory of an emotional. event, but it's no longer emotional. itself. You don't regurgitate that same. visceral reaction that you had at the. time of learning. So, the brain has done. this elegant trick of stripping the.

emotion from the memory. So, it's That's the That's the the. second benefit um is that it provides. It's not time that heals all wounds. It. is time during sleep and particularly. during dream sleep that provides. emotional convalescence. It's funny because there's a the. stereotype that we should never go to. bed angry at each other. You will wake up far less angry as a. consequence. Matt, we have a closing tradition on. this podcast where the last guest asks a. question for the next guest not knowing.

who they're going to ask it for. Um the question that's been left for you. from our previous guest, obviously they. didn't know who they're leaving it for, but uh it's a very I love these. questions when they're challenging. Um. what is the biggest way in which you are. a contradiction? Gosh, I'm a contradiction. in so many ways. I think. I'm a contradiction in the sense that. within my profession and with this field. of sleep, I feel very comfortable. I'm.

reticent to say confident, but I am very. comfortable to get on stage, you know, give a TED Talk in front of couple of. thousand people and my heart rate will. be very stable. I probably. I probably don't feel I I feel more. myself on stage alone in front of. thousands of people than I do at any. other time in my life. That's where I. feel most myself. But yet I'm a contradiction because off.

stage. I'm very insecure. I'm very much an introvert. I'm very. shy. Um I don't like being the focus of. attention. And so, those two things I've often. wrestled with, but the more people I've. spoken to sort of now being out in the. public sphere and sort of. sort of being more in the sort of public. intellectual realm, you start to meet, you know, very famous people, and you. meet, you know, musicians, and.

and what you learn is that they're very. similar, that they say that they become. this version of themselves on stage, and. then when they're off stage, they are a. radically different person. But I am. such a contradiction in that sense. I. feel very comfortable and very secure on. stage in front of thousands people. And. for many people, public speaking is one. of the most anxiogenic things you can. ask anyone to do. But for me, heart rate is probably in the, you know, mid-40s.

Uh, very relaxing for me. But then, put. me in a room, you know, a small room of. a couple of people, my heart rate's. probably through the roof, and I've. become very introverted. So, I'm a. contradiction in that sense. Um, yeah. Matthew, thank you. Thank you for for. making the time today. I've I've I've. wanted to speak to you for many, many. years, and you absolutely never. disappoint anybody. So, you're. That's very kind of you to say. It's exceptionally important work, and. as you said at the start of this. conversation, we often neglect the.

medicinal properties of a great night's. sleep over things like diet and medicine. or exercise, whatever whatever else it. is. But your your voice and the the the. passion that sits behind it has led a a. charge in society, which is waking us. up, no pun intended, to the um the virtues and the power and. the importance of having a great night's. sleep. But in a nice way, in a way that. I find it really empowering and. actionable, and that's the most. important thing. So, thank you for that, Matthew. Thank you, and thank you for saying that. last part especially. I I don't think I.

can um. lay claim to that sort of uh early on. I. think I'm doing much better as uh much. better. I'm doing a little bit better as. a public communicator, and being less. puritanical and dictatorial in my sleep. message. I think I did a terrible job. coming out. I'm learning and I'm being. more sensitive, but I'm always lovely to. hear feedback from folks about what I'm. not doing well cuz I would love to do. this better and better if I can. Um but. thank you for saying those kind words. and thank you again for having me on, giving me this opportunity to speak. I. now will anoint you as a sleep.

ambassador from this point forward, so. thank you so much again, Stephen. I. really appreciate you. Quick word from one of our sponsors. I. have to say I've been on a bit of a. journey with this brand because when I. started my business in new territories, when we first moved Social Chain to the. to New York City, the first place we. went to was WeWork. We moved four of our. team members out to New York City and we. built the business from there. Um I have. to say there's something magical about. WeWorks. I've spent the last two or.

three weeks in LA in a WeWork and as you. walk in the front door every day, it's. almost like that sense of community, that sense of magic, excitement, camaraderie is tangible. And you don't. get that when you're working at home. You don't get that often when you're sat. in your bed on your laptop. There's. something about getting out and getting. into a WeWork that makes me feel a sense. of entrepreneurship and and creativity. and building. And the way that WeWorks. are designed both both in the way that. they offer subscriptions so that you can. work, you know, on demand, but also that.

the flexibility of the contracts means. that it's just the perfect place for. businesses to scale their companies. And. if you haven't checked out WeWork and. you want to, you can go to we.co/ceo, where you can try out your local WeWork. for the day at 50% off. Just download. the WeWork on demand app and use the. code diary at checkout. You know, I never really usually pick. the chocolate flavored Huel. My favorite. are the banana flavor. I love the salted. caramel flavor. But recently, I think I.

in part blame Jack in my team, who's. obsessed with the chocolate flavor Huel. I've started drinking the chocolate. flavor Huel for the first time and I. absolutely love them. My life means that. I sometimes disregard my diet and it's. funny, that's part of the reason why. I've had a lot of guests on this podcast. recently that talk about diet and health. and and those kinds of things because I. am trying to make an active effort to be. more healthy, to lose a little bit of. weight as well, but to be more healthy. And the role that Huel plays in my life. is it means that in those moments where. sometimes I might reach for.

you know, junk foods, having an option that is nutritionally. complete, that is high in fiber, that is. incredibly high in protein, that has all. the vitamins and minerals that my body. needs, within arms reach, that I can. consume on the go, is where Huel has. been a game changer for me.