Dr. Matthew Walker: Why sleep regularity beats sleep length

Through evidence on magnesium, melatonin, and weekend catch-up sleep; Walker shows why regular bedtimes and light control predict early death

Matthew WalkerguestSteven Bartletthost

Nov 17, 20252h 17mWatch on YouTube ↗

EVERY SPOKEN WORD

155 min read · 31,133 words

0:00 – 2:20
Intro
1. MWMatthew Walker
  Here's the problem with magnesium supplementation when it comes to sleep. The first thing to note is that most forms of magnesium don't cross the blood-brain barrier, and sleep is produced by your brain. So, how can something that doesn't get into your brain affect brain process? All you're doing is creating probably expensive urine.
2. However, there is one form of magnesium that seems to have some evidence in favor of it, which we can speak about, but it doesn't stop there. There's so much new evidence that we have, including this myth of eight hours, my fear about giving melatonin to kids, why you keep waking up in the middle of the night, and the invention of the first new class of sleeping medication that I actually favor, and most people are not aware of it. Okay, let me write this down. Matthew Walker is back. And the world-renowned sleep expert and neuroscience professor...
3. SBSteven Bartlett
  Is sharing brand-new research to combat the sleep loss epidemic... And help you get the perfect night sleep.
4. MWMatthew Walker
  So, society, we have struggles with sleep at night due to many reasons, but no one teaches us this stuff.
5. (laughs)
6. And it's things like, say you go to bed at 11:00 one night, 1:00 AM the next night, then 10:30 PM the next night, and it's remarkable how many people do this. But studies have shown that you are statistically 49% more likely to prematurely die versus those people who are most regular in terms of going to bed and waking up at the same time. And worse, they had a 57% cardio-metabolic disease risk increase.
7. What the...
8. But science really teaches us that there are four pillars of good sleep, and then there's this incredible new study looking at sleep banking. And this is remarkable for people who are facing a sprint at work, or a medical doctor about to go on-call for the next 40 hours, a new parent. And we can go through all of that, but if you were to push me to say the three most impactful things that you can start doing tonight to start sleeping better, it would be...
9. I see messages all the time in the comments section that some of you didn't realize you didn't subscribe, so if you could do me a favor and double-check if you're a subscriber to this channel, that would be tremendously appreciated. It's the simple, it's the free thing that anybody that watches this show frequently can do to help us here to keep everything going and this show in the trajectory it's on. So, please do double-check if you've subscribed and, uh, thank you so much. Because in a strange way, you are- you're part of our history, and you're on this journey with us, and I appreciate you for that. So, yeah, thank you.
2:20 – 4:48
Sleep Changes Your DNA
1. MWMatthew Walker
  Dr. Matthew Walker, here in front of me, I have these cards, which I'm gonna reveal a bit later, but these kind of hold what you consider to be the four pillars of great sleep. But you also spend much of your professional career just studying the brain generally to understand human performance and how th- we can change our lifestyles, and also introduce some of these n- new sort of treatments to improve how our brain performs, and I wanna talk about all of that as well. But to start, for anyone that is unfamiliar with you and has been hiding under a rock-
2. (laughs)
3. ... how would you summarize who you are professionally, the sort of academic references you're drawing on, and the experiences and research you've done so that the viewer listening at home understands the full world that you operate in, study, and have experienced?
4. I am, in Europe, a scientist by trade, but my specialty is sleep, the effects of sleep on the brain and the body. And I've probably spent about the past two decades trying to understand exactly why do we sleep, because 50 years ago, the crass answer to the question why do you sleep was the following: you sleep to cure sleepiness.
5. Mm-hmm.
6. (chuckles) Which is the factious equivalent of saying, "Well, you eat to cure hunger." No, you don't eat to cu- cure hunger. You eat to support all sorts of physiological and biological benefits. But now, and this is not due to my research, this is all of the incredible colleagues whose sort of shoulders that I stand on, we've now had to upend the question. We now have to ask, is there any major physiological system in your body, or is there any operation of your mind that isn't wonderfully enhanced by sleep when you get it or demonstrably impaired when you don't get enough? And the answer now seems to be no. We- there is no such system. Even down to the level of your DNA, your sleep and how you are sleeping or not sleeping will change the very DNA nucleic alphabet that spells out your daily health narrative. And we can see it all the way up to society. Sleep can change the fabric of society. It can change how we interact with other people. It can change our belief systems. It can change how lonely or sort of hyper-social we are. So, to your question, I'm a sleep scientist by trade, and I suppose my mission has been trying to reunite humanity with the sleep that it seems to be so bereft of.
4:48 – 8:29
The Stigma Around Sleep and Laziness
1. MWMatthew Walker
2. We had a fantastic conversation last time, and my audience valued it t- tremendously. I know that 'cause we- we often survey our audience, and we- we get to see some of the- the backend stats. And this conversation about sleep is particularly personal to everybody listening, because when we surveyed our audience ahead of this conversation today, about 75% or 80% of the Diary of a CEO audience struggle with sleep for a variety of different reasons.
3. Mm-hmm.
4. So we actually asked them, 1,000 of them, their questions to ask you today. But also, the other reason I really wanted to chat to you is the science of sleep, I mean, as is the way of science, is always evolving. We're learning new things. And even since we spoke last time, there is new sleep science, which we're gonna talk about today. And one of those particular things we're gonna talk about is gonna be demonstrated using (rattles) this jar.
5. (laughs)
6. Because I always wanna know what the updated sleep science is so that I can be a better sleeper, because I agree with everything you said about how foundational sleep is in my life.
7. (laughs)
8. I- and, um, I didn't know this at the start of my career. I didn't know this, uh, even a couple of years ago, five years ago. I didn't know. I thought sleep was one of those things you could just take it or leave.
9. Yeah, I mean, and it's not your fault in so many ways, because if you didn't know what I know...You would just think, "Well, when I sleep my body is dormant and my mind, for the most part, is blank. So i- is it so catastrophic to lose, you know, an hour or two of sleep?" And, you know, you have to then think about, from an evolutionary perspective, it is such an idiotic idea to sleep because when you're sleeping, you're not finding a mate, you're not reproducing, you're not caring for your young, you're not foraging for food, and worst of all, you're vulnerable to predation.
10. Hmm.
11. So on any one of those grounds, and especially all of them as a collective, sleep should've been strongly selected against in the course of evolution. And my point is that, and it's often been said, that if sleep doesn't serve an absolutely vital set of functions, plural, then it's the biggest mistake the evolutionary process has ever made. And we now realize it didn't make a spectacular blunder, but really, I guess, to- th- the point of it is sleep is not a passive state. It's an incredibly active state both in the terms of the brain and the body. And so you, uh, should not feel, sort of, you know, remiss or ashamed that you didn't value the importance of sleep because firstly, as a subjective sense you just think, "Well, my mind was offline for a while." Second, we also know that we don't teach the importance of sleep in education. And doctors themselves, you know, there's a great study and they- what they found was that medical doctors across, I think it was about 11 different curricula around the world, they will only receive about 1.2 hours of education on sleep, but it's a third of their patients' lives. So there's a collection of, sort of, almost perfect storms that have happened to keep society ignorant of the importance and the value of sleep, and I think that's why we often so shortchange it, together with also something terrible, which is stigma. That people are so proud to say, "Well, I've been eating really healthy the past couple of months," or, you know, "I've been going to the gym, you know, three times a week consistently for the past year." No one is ever going out into soci- society and saying, "You know, I- I've been getting eight and a half hours of sleep consistently every night," because if you did people would say, "Really?" And there's a, there's a slight edge to the really which is that if you have time to sleep then you must not be busy, and if you're not busy you must not be important.
8:29 – 10:45
What's Stopping People From Sleeping?
1. MWMatthew Walker
2. So can you do me a favor and for the listener at home can you tell me what the different groups of people that are listening to this conversation right now are seeking? From the extreme end being sleep apnea, I get no sleep, I'm an insomniac, to the other end where maybe they're looking for marginal performance gains. Like what are the, what are the cohorts of people you see and the reasons why they're so interested in your work? They listen to your podcast. They read your books. What are the cohorts?
3. Firstly we have the collection of people who have insomnia, those people who have other sleep disorders like sleep apnea which we can speak about. There's another disorder called restless leg syndrome. It's a terrible disorder where your legs start to feel as though they've got this sort of creepy crawly feeling and you've constantly got to massage them and move them. It's a terrible disrupter of your sleep. All of these disorders are markedly undiagnosed, by the way. And then you've got another collection of individuals who they don't have any sleep disorders but they are either doing things that will dismantle their sleep, so either they're taking on things into themselves like alcohol, caffeine, THC that aren't the sleep helpers even though sometimes they think they are. And then you've got perhaps the internal things that will prevent you from sleeping well, things like stress and anxiety. And then you've also just got life (laughs) itself that can get in the way. And then moving from the sleep disorders realm to the I don't have a sleep disorder but I'm probably not doing it right, quote unquote, when it comes to sleep, then you've got the people who are obsessed about getting it right and they are the bio-optimizers, this sort of the, you know, the biohackers. And then you've also got... I work with a lot of high performance individuals who are really trying to just scratch out those last couple of percentages, either if- it's in business or often we're working with professional athletes. These are the people for whom two or three percentage point changes can be tens of millions of dollars or they can be the difference between standing on a podium at the Olympics or not. And so this is- it's a broad collection of wonderful characters.
10:45 – 14:35
The Shocking Link Between Weekend Sleep-Ins and Heart Disease
1. MWMatthew Walker
  And since we last spoke is there now a lot of new sleep science and understanding as it relates to sleep performance and these three categories of sleep deficient, sleep disorders, lifestyle factors, and then the optimizers?
2. Yeah. I think there's- there's a broad collection of new evidence that we have but maybe let me come on to the middle group. You know, I used to say that for people who were deficient in their sleep that sleep wasn't like the bank, that you can't accumulate debt... Oh, here we go. Okay. So what we can see here is that the jar used to be full, full of sleep credit when you're sleeping well and then during the week I'm short sleeping so maybe I'm only getting five hours a night so I'm constantly going into debt so I'm losing all of this wonderful sleep credit and my system is building up this collateral debt. And then we used to think that sleep was not like the bank, that once you've gone into debt, unfortunately, the lid is closed and even at the weekend if you try to pay it back you can't put back credit into the system. However, there was a study published from what's called the UK Biobank which is this incredible dataset, it's w-... revolutionary. And they studied, in this particular research, uh, paper, over 90,000 individuals. And what they did was they essentially split them down into those individuals who were short sleeping during the week, and then short sleeping at the weekend, and they compared them to those individuals who were short sleeping during the week but then long sleeping at the weekend. They were doing catch-up sleep.
3. That's me.
4. And that's so many individuals-
5. Yeah.
6. ... it turns out. If you look at the data, it's, it's remarkable how many people do this, this catch-up sleep behavior. But what was amazing is that in the people who were short sleeping during the week but long sleeping at the weekend, they had a 20% reduced cardiovascular disease risk relative to the people who were short sleeping during the week but also short sleeping at the weekend. Now, to be clear, both of those groups had a higher cardiovascular disease risk than people who were sleeping sufficiently during the week and sleeping sufficiently during the weekend, so I'm not saying that it's a completely free lunch. But for the first time, we realize that at least one system, major organ system in your body, is like the bank, which is that if your heart... At the weekend (coins jangling) you can (coins jangling) just keep putting credit back and your system doesn't suffer as much.
7. For your heart?
8. For your heart.
9. Okay.
10. But, again, many of the other major physiological systems don't show that. So work by people like Kenneth Wright at the University of Boulder, Colorado, he's shown that your immune system doesn't rebound after long sleep at the weekend, your regulation of blood sugar, your cognitive ability. So that's one way in which I've changed my mind regarding sleep and the bank. But there's a very different new set of data that has changed my mind completely about this idea of sleep and the bank. Now, what we've just discussed here is to say I went into debt, and then I was hoping to try and pay it off with credit at the weekend.
11. So the jar represents the debt that you have, the sleep debt?
12. Correct.
13. Yeah.
14. And what I'm trying to do is force more coinage (coins jangling) (laughs) in at the weekend to see if I can offset the debt that I created and get back to net- net neutral by the end of the weekend. Now, it turns out you can't do that, even if you sleep for as long as you want.
14:35 – 16:11
New Research: Sleep Banking for Low-Sleep Periods
1. MWMatthew Walker
  But here's this new remarkable data. It came from, um, Walter Reed Medical Army Institute, a researcher called Thomas Bolken. And what he was interested in was flipping the direction of the question. Not if I go into debt can I pay back with credit, but what if I know in future I'm going to face a debt, an upcoming debt? Can I do sleep banking?
2. Oh, so if I've got a big thing coming up where I'm traveling across the world and I know I'm gonna be sleep deficient, can I sleep a lot before it to create a... W- what would the financial analogy be?
3. So the, the financial analogy would be, let's say that we're coming up to Christmas-
4. Yeah.
5. ... and you're gonna spend lots on, you know, presents and all sorts of stuff. So I know that in October and November, I'm going to tighten my financial belt-
6. I see this.
7. ... so that when I go into the sort of Christmas period and I'm spending a lot more money, my bank account isn't hit as hard. I don't go into as much of a sort of a debt situation because I've built up credit.
8. So you can create sleep savings.
9. Correct. It's a sleep saving system. So essentially, you know, (coins jangling) what he was able to do, not just put the jar to full, but he was actually packing in even more so that you almost got this wonderful overflow of sleep.
10. How did he know?
11. He didn't. It was the experimental hypothesis.
12. A- and but
16:11 – 19:01
Boost Cognitive Performance With This Sleep Hack
1. MWMatthew Walker
  how did they prove it?
2. So what they did is that they woke you up to a period when you're going to have two or three nights of either no sleep or marked sleep reduction. And in the week beforehand, with these Army cadets, instead of being limited to eight hours of time in bed, they were able to get 10 hours of time in bed and they could sleep all that they want. And so they went from probably an average of about seven, seven and a half hours of sleep to about eight and a half, almost nine hours of sleep. So they were extending their sleep duration, and so that they had built up this buffer. It's almost like a sort of a, a sleep safety net that's in place so that when you go into the tumble of sleep deprivation, you're sort of almost bolstered and you're lifted higher, and therefore your degree of impairment that you suffer under conditions of sleep deprivation is significantly less if you banked sleep beforehand versus those people who were just sleeping normally and then faced the deprivation. They went down much further in terms of their cognitive and mental performance.
3. So he gave them challenges and tasks to do-
4. Correct.
5. ... in two different groups. One group had sleep savings saved up from sleeping well the previous week, one group didn't.
6. That's right.
7. And they performed w- remarkably different?
8. So both of them were impaired relative to a sleep rested person.
9. Okay.
10. However, the people... It's sort of, you know, how, how much of a drop in your-
11. Mm-hmm.
12. ... cognitive performance do you suffer? And what he found was that people who had built up this credit, this savings account of sleep in the days and the week beforehand, they suffered about 40% less of an impairment relative to the people who had not created any savings plan. Now, they weren't in debt. They were just net neutral.
13. Mm-hmm.
14. But boy did they drop quickly. Whereas those people who'd had some-... cash in the sleep credit system. They didn't fall anywhere near as far. But this is remarkable for people, l- like you were saying, who are facing, let's say, if I've got a sprint at work or I'm a medical doctor, I know I'm about to go on call for the next 40 hours, you're a military, aviation, all of the... new parents, all of these circumstances are places where now we know, athletes is a great example, when we work with ath- athletes, people like Michael Grandner have demonstrated that athletes sleep terribly typically the night before a huge performance. No ma... you know, of course, the nerves.
15. Mm-hmm.
16. But what you can do is you can have them bank sleep in the days before when they're not as nervous, and therefore their performance doesn't suffer as much, even though they know they're going to be deprived.
17. Sleep is so important, isn't it? And I think everybody now knows that because of people like yourself, well really,
19:01 – 20:29
3 Ways to Instantly Improve Sleep Quality
1. MWMatthew Walker
  you know, you were the real pioneer in pushing this subject into the world. I remember when you first went on Joe Rogan's show, the amount of my friends that sent me that episode-
2. (laughs)
3. ... and then sent me your book was just staggering. It was like that was the catalyst moment, I think, in society for the mainstream to really start talking and caring about sleep. However, there's still so many people struggling, um, because of all the factors that you talked about when we're talking about group two, who have those lifestyle factors, the stress, the psychological factors, the trauma, et cetera, et cetera. What can we give them, those people, the people that really, really struggle? Maybe they haven't got a disorder, we'll come to the people with sort of sleep disorders later and we'll talk about optimizers, but what, what is the new information or advice that we can give them that will help them once and for all sleep eight hours a night and get their life back?
4. If you were to push me to say what are the three most impactful things that you can start doing tonight to start sleeping better, it would be the following. Digital detox.
5. Okay, let me write this down. Digital detox, okay, and what does that mean?
6. One hour before bed, try to limit activating social media engagement, email, and text messages that are going to trigger you.
7. Only-
8. It's fine to listen to a podcast, you know-
9. Thank God for that. (laughs)
10. (laughs) You heard it here, folks.
11. Yeah. (laughs)
12. Right
20:29 – 21:48
It's Not Blue Light That's Keeping You Awake
1. MWMatthew Walker
  from my book. Um-
2. But it's also good to like and subscribe, would you say?
3. I would say that, you know, like and subscribe and then just click here so that you can get the gr- latest notification-
4. Yeah.
5. You get that bell, just click on the bell icon so that you've-
6. Okay.
7. (laughs)
8. (laughs)
9. So, it's not a problem of blue light. A quick aside, we've been taught this myth of the blue light effect-
10. Yeah.
11. ... from devices and it really is a myth because an incredible Australian researcher, a guy called Michael Gradizar has almost single-handedly changed the, the, what I think of as being the zeitgeist for a while, after a very influential paper, which is a great paper, and what they showed was that one hour of iPad reading before bed ended up impairing your melatonin. It disrupted sleep, it reduced the amount of dream sleep, and even after they stopped reading the iPad, the blast radius impact on your dream sleep lasted a week. It's almost like the drug needed to get washed out the system, that even when you, you'd stopped using technology for an hour before bed, the impact of that technology, even though you'd stopped using it, could still be seen in the echo of sleep disruption for a week later. It was a very influential study in a very prestigious journal.
12. When was that? A while ago.
13. That was probably about 10 years ago.
14. Okay.
15. But then Michael Gradizar, this incredible Australian researcher started to say, "Well, I can't replicate these findings."
21:48 – 24:15
Melatonin Doesn’t Make You Sleep – Here's What It Does
1. MWMatthew Walker
  And what he was discovering is that it's not the blue light that's the problem. Now, the blue light will change aspects of your melatonin, and melatonin's a hormone, it simply tells your brain and your body when it's nighttime, when it's time to fall asleep. It doesn't participate in the generation of sleep. Melatonin is like the starting official at the 100 meter race. It brings all of the racers to the line and it begins the timing of the race, but it doesn't participate in the creation of the race itself. That's a different set of chemicals.
2. It doesn't make you go to sleep.
3. It doesn't make you... And if you look at what we call meta-analyses where we gather together all of the individual studies on a topic and we put them in a big statistical bucket, what they found is that melatonin will only improve the speed with which you fall asleep by about, um, 3.4 minutes, and it will only increase the efficiency of your sleep by about 2.2%, so not much more than placebo. Um, so melatonin is, i- it's... Now, the placebo effect is the most reliable effect in all of pharmacology, so, you know, m- maybe no harm, no foul. I would say, and don't forget, I will come back to the three, but when it comes to melatonin, be careful. More isn't always better, and you run the risk of confusing your morning brain into a dense nighttime fog. And what I mean by that is 10 milligrams or 20 milligrams of melatonin is what we call a supraphysiological dose, which again is just a fancy medical term to say it's a size of magnitude of melatonin that your body would never naturally release. It's far greater. So melatonin is the signal of darkness, and normally by the morning hours, our natural release of melatonin has stopped and you're down to zero levels again.
4. In the morning-
5. So you wake up and your body no longer has the signal of melatonin saying, "It's night, it's night, it's night." But if you've dosed yourself with 10 milligrams or 20 milligrams of melatonin, you run the risk of saying, "Well, yes, I know it, u- k- uh, quote unquote knocks me out," but the problem is in the first, you know, f- three or four hours of the waking morning, you're struggling because you're in this fog of a hormonal melatonin, a hormonal signal saying it's still pitch black. Now, it's not. It's bright light outside, but your body is fooled into thinking it's pitch black because you've dosed yourself too high and no wonder you're reaching for two or three cups of coffee in the morning-
6. Yeah.So
24:15 – 25:41
How Much Melatonin Is Right?
1. MWMatthew Walker
  what, what dose of melatonin should I be taking?
2. Somewhere between probably about .1 to three milligrams.
3. And do you advise melatonin for people?
4. Yes, in two conditions. The first, or circumstances, I should say. The first is when you're going through jet lag. Wonderfully helpful, but timing is critical. You need to create that, sort of, that artificial signal of night, because let's say that you and I, here in Los Angeles, we're both going to fly back to London tomorrow. And London is eight hours ahead. So we fly overnight, we arrive in London, and then that first night, let's say we decide to go to bed, uh, I decide to go to bed in the hotel at midnight. The problem is, here in Los Angeles, on my body clock, it's still 4:00 PM, 'cause London's eight hours ahead. So my melatonin is not going to rise for probably another six or seven hours. So I need to artificially hijack my melatonin system and tell my brain, "Oh no, it's not 4:00 PM. It's instead, it's midnight." And so there, under conditions of jet lag, very helpful. The second is if you have a circadian rhythm disorder. Let's say that you're someone who has a, uh, an advanced circadian phase. What that means is, you're someone who really can't get sleepy until 3:00 or 4:00 in the morning, and you would prefer to be sleeping throughout most of the day, so you, you're almost
25:41 – 27:12
The 1% With a Nocturnal Clock Who Can't Sleep Until 3 AM
1. MWMatthew Walker
  nocturnal.
2. Is that a genetic disorder?
3. And yes, it's a genetic disorder in part.
4. How many people have that?
5. Probably 1 to 2% of the population have a very severe ad- what we call an advanced circadian phase disorder. But their melatonin can also be helpful, because once again, their melatonin, part of their problem is that their melatonin is very delayed. So they don't get the signal of, "Oh, it's night," until maybe 4:00 in the morning. You and I, we start to get our signal of melatonin, depending on our chronotype, by somewhere up between about 9:00, 10:00 or 11:00 PM. They may be delayed by five hours. So if we can give them melatonin, we can artificially try to fool their brain into thinking it's actually earlier in their biological rhythm, so they sleep earlier and they're more in sync with the rest of society.
6. How does someone know if they're that type of person, if they have that disorder? Is there, there's no way to test, is there?
7. Well, what we typically do is we will bring you into a laboratory and we will measure your innate level. So we will shut out, sort of all windows, all clock faces are gone, and we just let you run your natural rhythm.
8. Mm-hmm.
9. And they have the same rise and fall in melatonin, just like you and I do, except where it's doing that rise and fall of melatonin on the 24-hour clock face is radically different.
10. Oh, okay.
11. For you and I, it's you know, 9:00, 10:00 PM, 11:00 PM at night when we're starting that melatonin crescendo.
12. Mm-hmm.
13. For them, it's 4:00 in the morning. So we can measure it. It's not in their minds, it's not their choice. It's a biological
27:12 – 30:19
Is Melatonin Really the Magic Sleep Pill?
1. MWMatthew Walker
  edict.
2. Are you concerned that melatonin is becoming more and more popular as a way to solve lifestyle issues that have caused sleep impairment? Because I'm seeing loads of s-, you know, I'm an investor, so I see lots of companies now pitching me different products that have melatonin in them as a sort of day-to-day sleeping supplement.
3. I think I'm really torn. I've been on both sides of this argument, and I'm cautious a- about it for two reasons. The first is in pediatric populations. Here in the United States-
4. Pediatric?
5. Yeah.
6. What does that mean?
7. So the people's use of melatonin in kids is increasing. So in pediatric populations, it's increasing exponentially. And in fact, if you go down the, sort of the supermarket aisles here in America, often if you go into sort of the, the health sort of food section, there's this big purple section. That's the melatonin section, and a large proportion of that is there dedicated to gummies for your children with melatonin. And there was a study that was published about three years ago that showed here in America, over the past 10 years, there has been a 503% increase in poisonous overdose admissions to hospitals of melatonin in the past 10 years. 503% increase. So firstly, we've got to be a bit careful. The second reason is that melatonin is a bioactive hormone, and it's also involved in reproductive development. And there were studies done back in the 1970s, I think, where they were looking at juvenile male rats, which is to say male rats who were going through adolescence, and they were dosing them with high amounts of melatonin. And what they found is that that stunted the development of the testes, of the testicles, and it caused testicular atrophy. Now, these were very high doses, but we've got to be a little bit careful. We think, we say, "Well, melatonin's a natural hormone, so anything natural is safe." Melatonin overall in terms of its safety profile is very safe. It's actually a very good antioxidant. But you've got to be careful because things like, for example, testosterone supplementation in males. What we know is that if you're injecting testosterone, after a while, after maybe 18 months or so, the testicles themselves will stop producing their own testosterone. And even if you stop the administration of the exogenous testosterone, the injection, the testes never return their function of producing testosterone. Now, we don't have a- any evidence yet that that's the case, that if you keep taking melatonin at high dose, your body, the fear would be, shuts down its own natural production of melatonin. I've seen no evidence of that. In fact, I've seen evidence to the contrary, that even after about six months or even 12 months in certain small cities, when you stop melatonin, the production starts again naturally. It, it seems to be fine. Problem is, people haven't been taking melatonin for just 12 months. They've been taking it for years.... we've got no idea what happens after
30:19 – 34:51
The Trade-Offs of Sleep Medication
1. MWMatthew Walker
  years.
2. That was my hesitation when the first time someone offered me melatonin, is from doing this podcast and speaking to smart people like yourself, I've come to learn this sort of principle that if you start making something for your body in terms of a hormone, if you start sort of e- um, consuming something externally, like testosterone, your body will say, "Fine, I don't need to do this." It will try and return to that level of balance where the quantities in your system are maintained, which means it kind of learns to shut down. And I always think about the case of testosterone 'cause men know that if we start injecting testosterone, then we're gonna have to pretty much do it forever-
3. Yeah.
4. ... um, if we want the le- those levels to be the same.
5. But yeah, that's the worry is that there are no free lunches in biology, and usually if you fight biology, you typically lose (laughs) .
6. There's no free lunches. There's always a trade-off.
7. Yeah.
8. And some of my friends often, like, s- talk to me about, like, these miracle things or this thing, or, "Take modafinil and everything will be fine," and da, da, da, da. I go, "Yeah, but what's the trade-off?" And I get most concerned when they say, "There isn't one."
9. Yeah.
10. 'Cause then I go, "Shit, we don't know it?" (laughs)
11. Yeah. You've got to be careful because absence of evidence is not evidence of absence.
12. Hmm.
13. Be very careful when you're doing that deal with, with your physiology. So to come back to the, sort of the three things, the first thing we were mentioning is digital detox. And don't worry about the blue light. Worry about light in general, I'll come on to that 'cause that's the second, but Michael Gradazar is saying, what he found is that the blue light doesn't really disrupt your sleep. It's a combination of first, these devices that we use are attention capture devices, and they are designed to fleece you of your attention economy, and they do it ruthlessly well. They've spent tens of millions of dollars designing these products to do that. So what happens is that these devices become hugely activating, and as a result, they essentially will be a mute button on your sleepiness. So you could be there, you get into bed, it's 11:00 PM. You think, "I am so tired, I was falling asleep on the, the, the couch watching television." And then you get into bed, you start going onto social media, and then you start doom-scrolling, and then you j- get into this what we call bed rotting, where you just sit there, and now you look at the clock, and it's no longer 11:00 PM, it's 1:00 AM, and you've just done sleep procrastination. Now, it turns out that it's, yes, that, that these are attention-grabbing devices that will mute your sleepiness, but you have to be of a certain personality type, he found. Not all of us are vulnerable to this sleep disruption of devices. You have to be someone who is perhaps neurotic, someone who has high impulsivity, or someone who is perhaps high anxious. If you are of any of those kinds, you should be really careful about your use of technology in the bedroom. Now, for me to, you know, sit here and say, "Look, t- s- put your phone in the car, in the garage," and that way, you know, that's what I would love because w- what we've learned to do in this modern era is the first thing when you wake up, what is it that you do?
14. No, no comment (laughs) .
15. (laughs) .
16. Not till we're new.
17. You (laughs) .
18. (laughs) .
19. It's just you and I.
20. Okay.
21. Um-
22. I grab my phone before my eyes are even open.
23. And what happens is this sort of small tsunami of anxiety washes over you because as soon as you unlock the phone, it's everyone else's agenda for your day, but your own. And it's a terrible way to wake up. Have you ever had the experience where you've got to wake up for an early morning flight, and it's a critical flight? You know that that night is not going to be a good night of sleep. It's going to be a shallow kind of sleep. It's what we call anticipatory anxiety. You are anticipating an anxious event in the morning. And studies have shown that when we create this anticipatory anxiety, the amount of deep sleep that you have drops significantly. You don't sleep as well. And therefore, if we just do this little sort of version, this L-I-T-E version of the morning flight, which is we know that when we go to bed and we put our phone down, we know that when we wake up every morning, we're just going to open it up to that hit of anxiety every morning. No wonder our sleep can start to get shallow. Now, I'm not going to sit here and say, "Well, don't take your phone into the bedroom," because the genie is out the bottle. And no matter what I say, it's not going back in anytime soon. And a friend of mine, Michael Grandner, uh, has got this beautiful, uh, framework where he says, "You can take your phone into your bedroom. It's fine. But you can only use your phone standing
34:51 – 35:32
The Key to a Digital Detox
1. MWMatthew Walker
  up."
2. Oh.
3. (laughs) .
4. What's his name?
5. Michael Grandner. He's br- brilliant-
6. Tell him to mind his own business.
7. (laughs) .
8. (laughs) .
9. And, and what happens is that y- you're there and you think after about seven or eight minutes, "Oh, I'm just, I'm just gonna have a bit of a sit down here," as soon as that, phone goes away. So I would say that digital detox is the first friend that will really help your sleep. The, the second is regularity. And we'll come on to regularity when we speak about, you know, what really makes for good sleep. If you were to only do one thing, not three things, but just one thing, go to bed and wake up at the same time, no matter whether it's the weekday or the weekend, regularity is king.
35:32 – 36:49
The 4 Macros of Good Sleep: QQRT
1. MWMatthew Walker
2. Okay, so that's the third pillar.
3. That's correct. Regularity.
4. Regularity. Okay. And then I have the T for timing.
5. Correct.
6. Which we'll go through these. Um, quantity, which we've talked a little bit about already, and quality.
7. Correct. So when I looked at the science, for me, I created this framework of the four macros of good sleep. You've heard of the three macros of food-
8. Yeah.
9. ... macronutrients, fat, protein, carbohydrate. To me, there are four macros of good sleep, and it's QQRT, QQRT. And it stands for quantity, quality, regularity...... and timing. And think of it less like pillars, but the four legs of a chair. And if any one of these becomes unstable, the chair will topple over. So I'll probably start with the one that people have heard me bang on about, which is quantity. Seven to nine hours, th- this myth of eight hours is nonsense. It's a wonderful range, seven to nine hours, and what we know is that using that sweet spot of seven to nine hours, when you get less than that, the shorter your sleep, the shorter your life.
36:49 – 42:35
The Minimum Sleep Needed to Stay Alive
1. MWMatthew Walker
2. Fuck.
3. Short sleep predicts all-caused mortality. Now we say that there's the minimum of seven hours of sleep, and some people have argued, perhaps correctly, that, "Look, if you look at these mortality curves, there's not much of a percentage difference between sleeping six hours versus the seven that you're telling me is minimum. So six hours is just fine. So all of this nonsense and rhetoric is, is, is silly from you." And I think they've made a conflation because seven hours is the minimum amount of sleep that you need to survive. Because the way that we quantify what minimum is, is based on whether you die or you don't prematurely. The amount of n- sleep that you need to survive is different than the amount of sleep that you need to thrive. And people will conflate the former with the latter. So you've got to be careful when people are sort of touting on social media saying, "Well, no, but look, you, there's not much difference between my sort of survival rate on six hours versus seven hours." Y- you may have a, just as much of a long life, but the quality of your life will be very different. So that's quantity, seven to nine hours.
4. And is that... Does it change for parents, by the way? Because I- I've met so many parents that seem to be functioning better than me, and they've got four... They're having like four or five hours sleep. Did evolution not give parents any leeway or anything when they have kids that suddenly their brain changes and now they can survive with less sleep?
5. The evidence doesn't suggest that-
6. Hm.
7. ... once you go through parenthood, you get some magic sort of, you know, immunity shot that makes you, you know, resilient and n- not vulnerable to a lack of sleep. And in some ways you could argue because we used to, you know, live as a collective tribe and we would share duties, at that point, you know, mother nature doesn't really worry too much about you now because you've already procreated and you've passed on your genetic code. So you are now the, the sort of the... you know-
8. Oh, yeah.
9. ... the not particularly well, you know, cared for individual through evolution, it's your offspring-
10. Damn.
11. ... that gets...
12. So it sacrifices you in a way. I mean that's what we see in the animal kingdom. I, uh... W- did you see that documentary about the octopus?
13. Yeah. It, it was just... I mean, m- m- I thought it was a beautiful documentary but, um...
14. The TLDR for anyone that hasn't seen it is once the octopi- and I'm gonna completely butcher this so please ignore. Um, once the octopus has given birth, it dies? Basically it doesn't move out of that hole and it dies? Is that rough?
15. Well, I don't know if, if it dies but its level of, of active life.
16. I searched, "Does the octopus die after reproduction?" And it says, "Yes. Female octopuses die after their eggs hatch. After laying eggs, a female stops eating and devotes all of her he- her energy to protecting and oxygenating them until they hatch. Once they do, she dies shortly after, a process called semelparity, meaning they re- re- reproduce only once. This death is triggered by hormone changes from the optic gland similar to mammalian pituitary glands. And males die shortly after mating as well, usually within a few months." Th- that is wild.
17. In some ways it's, (laughs) you know, it's, it's tragic and it reminds me I'm so glad that I'm n- not an octopus. But... (laughs)
18. (laughs)
19. But, but coming back to it, so for... th- there doesn't seem to be some, you know, magic cloak of invincibility that you put on when you go through parenthood. Certainly what we know is that the number of individuals who can survive on six hours of sleep or less and show no impairment in either their brain or their body rounded to a whole number and expressed as a percent of the population is zero. So quantity matters but it turns out that we got it wrong in thinking that was the only thing because then came quality, so QQRT. Quality is defined in sleep science as two things. The first is something that your sleep tracker will measure, which is the continuity of your sleep. Meaning do you sleep in one or two nice long bouts throughout the night? That's good quality of sleep, nice continuous bouts. Versus your sort of sleep is very fragmented by all of these awakenings, that's very poor quality of sleep and the way that you can measure it in your sleep tracker is just by looking at the app and there'll be something called sleep efficiency. Sleep efficiency is defined as the following; of the time that you're in bed what percent of that time is spent asleep? And what we like to see is you north of 85% or above. So this is kind of like the user's guide to sleep trackers.
20. Okay. Okay.
21. What I want to see is 85% or more. If you're less than that, we need to have a conversation. That's number one good quality of sleep. The second which is what... sort of what y- these trackers can't really do but I can do in the sleep laboratory when you look like a spaghetti monster 'cause I've put electrodes all over your head, I can measure the quality of your big deep slow brainwaves of deep non-REM sleep and that is a second measure, the power of those big slow brainwaves, that's a second measure. And quality seems to be as predictive as quantity in making a difference not just to your all-cause mortality but quality even more than quantity when it comes to mental health has been showing the biggest signal.So again, it's not that quantity doesn't matter. You do have to get sufficient amounts of sleep. But quality as much as quantity should be paid attention to. And I haven't said that enough.
22. Mm-hmm.
23. The next is
42:35 – 46:37
How Sleep Regularity Predicts Life Expectancy
1. MWMatthew Walker
  where we came to in our sort of three things that I was saying. The first is digital detox. Then the next thing I said is regularity. This is somewhere where I've also changed my mind on. I've doubled down on regularity. There's a study that also came out of that same data set that I described. It's called the UK Biobank Data. And now they didn't look at 90,000 individuals but they looked at 60,000 individuals and they decided that they were going to compare and split them into quartiles. So the most regular to the second most regular to then sort of the third most regular, and then the final quartile was those who were the least regular.
2. And what does regular mean in this context?
3. Good question. Highly regular individuals plus or minus 15 minutes in terms of going to bed and waking up at the same time.
4. Oh.
5. In other words, a total wiggle room of 30 minutes.
6. Oh, okay. So if I'm always going to bed at 9:00 PM and I do that five days in a row-
7. Yeah.
8. ... I'm regular timing really.
9. So, so it's, it's regularity in terms of when you're going to bed and waking up.
10. Okay.
11. So it's, you're right, it's timing in a way.
12. Okay.
13. But I'll come on to why there is a separate T for timing in just a second. But regularity here was, okay, plus or mi- So let's say you go to bed at 8:45 PM one night, and then 9:00, and then 9:10 PM and then you're back to 8:00. That's beautiful tight timing. I like that. Whereas the, those people who were least regular, they were 90 to 120 minutes disparate. They were going to bed, let's say at 11:00 one night, then 1:00 AM the next night. Then they were going to bed at 10:30 PM and then they were going to bed at 12:30. They were all over the map. So what they found was that those people who were most regular versus least regular, so they compared the extremes of these two. Those people who were most regular had a 49% relative decrease in all-cause mortality. So they were 49% less likely to prematurely die than those people who were least likely to die. They had a 39% cancer mortality risk reduction. Great. They had a 57% cardio metabolic disease risk reduction. So that was stunning. That regularity was incredibly powerful as a predictive signal of your different forms of mortality. That wasn't the best part of the paper though. They had also measured quantity as well as regularity in these same individuals. So then they decided to say, "Well, I'm going to take our measure of quantity and regularity and we're going to put them both in the same statistical bucket and do a Coke Pepsi challenge to see which one wins out in terms of predicting all-cause mortality." We all bet in the sleep field, or at least I did, it was going to be quantity. I was wrong. Regularity beat out quantity in predicting all-cause mortality and by quite some margin. Now that doesn't mean that you can now go away and say, "I'm gonna start sleeping four hours," but incredibly consistent four hours. You need both quantity and quality. But goodness, does regularity seem to carry a massive signal? So coming back to those three things, I would say digital detox, just go to bed and wake up at the same time. And the final thing is light. In this modern world, we are a dark deprived society. We get what I call junk light at night. So you've heard of junk DNA? Well, we get junk light at night. We don't need all of this light and it fools our brain into thinking it's still daytime outside. So no wonder as a society we have some struggles with sleep at night. Now that's due to many reasons. Stress, too much caffeine, alcohol, THC. But excessive light is one of the easiest things that you can do. So for the next seven days, just do me this experiment if you can. Set an alarm one hour before your normal bedtime. When that alarm goes off, turn off, and I, I do this myself, turn off almost all of the lights in your house.
46:37 – 53:11
Try This 7-Day Sleep Enhancer Challenge
1. MWMatthew Walker
2. When you say all of the lights, do you mean the little red light on my smoke alarm or-
3. No. That's fine. But you know, so my wife and I, one hour before bed, almost all the lights, we've got sort of this little set of this, this sort of light that goes around the television, the back of the television so it kind of looks like the television's cool and illuminated. I will set that down to about 5% of brightness and all of the rest of the lights out. So you can kind of just still see some illumination. So I'm not sort of, you know, looking desperately uncool and, uh, in, in front of it when I'm tripping over things 'cause it's complete black. You know? Then start cooling the house or the room as best you can to around about 67, 68 degrees Fahrenheit or about 18 degrees Celsius. We can speak about temperature, but just do this experiment for the next seven days. One hour before bed, the alarm goes off. You switch off all of the lights and ask the following question. Do you feel sleepier? Is it soporific? Does it make you feel more sleepy as a result? But don't stop there. What you've gone and done is the first positive experiment, which is you've gone from the no intervention, lights are on, to then the Matt intervention, which is now the lights are off for one hour before bed. Don't just ask, "Is my sleep better when the lights were out for one hour before bed?" Once that seven day period has finished, go back to doing what you were doing before, which is keep all of the lights on and ask yourself, "Did my sleep get better when I did the intervention? And did my sleep go back to being worse when I stopped?" Because I'm trying to teach you bidirectionality in the experiment. Does that make some sense?
4. Yeah. So you get to s- you get to basically do an AB test.
5. Correct.
6. Yeah.
7. You get to see both sides of the equation. And with that it's more proof positive than just one direction alone 'cause who knows, it could just be a placebo effect.So regularity, coming back to it, is critical. So we've ta- spoken about QQR, quantity, quality, regularity.
8. On the qu- um, the-
9. Regularity.
10. ... regularity point, why?
11. Mm-hmm.
12. What's going on in our brain that's m- making it, from a hormonal perspective or other, that's making it important for us to sleep at the same time?
13. That's a bloody great question. People don't respond to rules, they respond to reasons, not rules. So let me try and explain the reason behind the sort of the rule. When it comes to regularity, we have something called a circadian rhythm that we've spoken about, and there's a clock that sits inside of your brain, deep in the middle of the brain. So we have, it just turns out, a brain here. Lovely. Okay, so we've got one of these hemispheres here, and then I'm just going to take out what we call the subcortical sections, so these are the areas that are below the subcortex. So here is the brain. So this is the front of the brain, the back of the brain, top of the brain, and here's the brainstem. And it turns out that right in the middle of the brain, right here, there's an area called the hypothalamus. Now here, this structure here, this is the thalamus. This is the sensory gate of your brain. So all of your five senses, sound, touch, taste, smell, they all flood into this gate called the thalamus, and then the thalamus will decide whether it sends those sensory signals up to your cortex. And when it sends the sig- signals up to your cortex, you start processing them, and you become consciously aware of the external world. Now, as we're falling asleep, just as an aside, what's interesting is that this gate, the sensory gate, the thalamus, once we start to fall asleep, the gate will close shut. Now your eyes are t- technically still seeing, your ears are still hearing, your tongue is still tasting, but because the gate of the thalamus, the sensory gate closes shut, those signals that are coming into your brain are no longer sent up to your cortex so you stop perceiving the outside world, which is just simply a different way of saying you've fallen asleep. Now, the hypothalamus, you've heard of hypo, sort of hypertension or sort of, you know, hypothermia, that means lower. So here's the thalamus. This area here is called the hypothalamus, and it's a tiny structure, but within that structure contains a nucleus, and that group of cells, the nucleus, has a fancy term and it's called the suprachiasmatic nucleus. But the suprachiasmatic nucleus is your master 24-hour clock. Every cell in your body has a clock inside of it. But this is the master clock. It's like Lord of the Rings, th- there's one ring to rule them all.
14. Mm-hmm.
15. Well, there's one clock to rule them all. And here in the suprachiasmatic nucleus, you get the 24-hour rhythm of being awake and being asleep, being awake and being asleep. How does your brain keep quartz-like precision 24-hour clock time? How does it do that? The way it does that is that it uses signals such as light and dark-
16. Fr- fr- from your eyes.
17. ... from your eye. And so when light comes through the retina, it tells the hypothalamus, "It's daytime and therefore you should be awake." And its rhythm starts its awesome sort of upswing, and temperature can do this and feeding can do this, all sorts of different things, but for the most part, light is the principal governor that essentially acts like electrical, I should say photon fingers, that pops the wristwatch dial out and resets it precisely so 24 hours every single day. Because if you're left in the dark with no signals of light, your clock isn't precise. It drifts to about 24 hours and 15 minutes, so you start going forward a little bit every single day if you go into a cave and people have done this experiment. The thing that keeps it precise is light. So you need light to keep a beautiful 24-hour rhythm. C- one of those things that's under the control of your 24-hour rhythm is your sleep-wake cycle.
18. What if I'm doing exercise?
19. Exercise is a wonderful entrainer of your circadian rhythm as long as you're doing it at the right time. So if you're starting to exercise at 3:00 or 4:00 in the morning, that's not good because that's an activity signal that's going to confuse the brain into thinking it's the active period which is normally, because we're a diurnal species, the day. And it's the same thing coming back to my point of regularity using light as the best way to help with that regularity because light, if it's artificial at night, fools your brain into thinking that it's daytime still outside.
53:11 – 1:00:50
How to Tell If Your Room Is Dark Enough for Sleep
1. MWMatthew Walker
2. I mean, is there any such thing as non-artificial light? I mean, I, I mean, I guess with the sun, but, I mean, is there a type of light that I could use at night, like candles or something or...
3. Yes. Below 30 lux-
4. Right.
5. ... is not going to necessarily do you a disservice. Probably below 50 lux. Now, lux, L-U-X, is just a measure of light intensity, and you can download on the app store a free lux meter, and if you're an idiot nerd like me, you're going all over the house at night and you're sort of putting it in different loca- and you're seeing, "Oh, God, is there any kind of white spots here where, you know, the lux is too high?" But you need to drop that, that lux. By the way, it's a great way, if people want to say, "Look, my REM sleep is deficient, how can I get more REM sleep?" There's a great study where they did something similar to what I'm telling you now. 90 minutes before bed, they turned down the lights to below 30 lux and they pulled out all of the blue light, and just that trick of dropping the lights down 90 minutes before bed below 30 lux, making it warm yellow light, increased their REM sleep by 18%.
6. Wow.
7. It's a huge margin, so no need for pharmacology. But to your question, why is regularity important? Well, I told you that light is one of the signals that can create regularity. It turns out that your behavior-... is another thing that will tell your brain. So meaning, when you go to bed and wake up at the same time, it acts like an anchor. It anchors your circadian rhythm, and it tells you, almost like a scene in a movie, this scene is now complete, a new scene starts, this scene is complete, a new scene starts. So every time that you're going to bed at the same time and waking up at the same time, you are feeding the suprachiasmatic nucleus, the master 24-hour clock in your brain, you're feeding it signals of regularity. And when it feeds on signals of regularity, it improves the quantity and the quality of your sleep. Your circadian rhythm likes consistency. It likes regular signals. When you feed it signals of light, of activity, of waking up, going to bed, you improve the quantity and the quality of your sleep. That's the reason behind the underlying rule.
8. So having a TV in your bedroom is a terrible idea then, because if, on that behavioral point, if I'm getting in bed but then I'm staying up for three hours watching Netflix, my brain is gonna be quite confused about, like, the behavioral pattern of what, um, what I'm doing in my life. It's not gonna associate the bed with sleep, it's gonna associate the bed with movies.
9. That's one of the problems that we call con- it's called conditioned arousal, which sounds a lot more salacious than it actually is. It's a term that we use in sleep medicine, which may explain insomnia. So with insomnia, let's say that the first time you go to this thing called a dentist and you get in the chair and it's kind of cool, you recline back and, you know, you think, "This is fine." But then after about 14 or 15 visits, when you get into that chair, you are no longer looking forward to getting into that chair, are you? Why? Because you've learned the association that being in that chair typically leads to a bad outcome. (laughs) Now, the same thing is true with the bed. If you start associating the bed with anything other than sleep, and we give you a pass in terms of sex, but sleep and sex, anything other than that, you start to learn that this thing called my bed is this place where I'm awake, where I work, where I eat, where we have conversations, where I watch television. And so, you know, if I were to... And, um, again, I'm stealing Michael Grender's point, but if I were to s- say to you, bed, sleep, bed, sleep, bed, sleep, bed, sleep, bed...
10. Sleep.
11. Okay. If I were to say, bed, scroll, bed, eat, bed, work, bed, sleep, bed, TV, bed... You've-
12. S- yeah.
13. Confused.
14. Yeah.
15. Because there's no predictive signal. You've never bound an association. Now, the way this works to your disadvantage in insomnia is the following. The insomnia event that begins the insomnia is typically not the thing that maintains the insomnia. So let's say that I, um, had experienced a really difficult bereavement and that triggered a form of insomnia where I couldn't sleep because of the bereavement. Gradually, the bereavement is not the thing that's going to maintain my insomnia. It's because every time I have been going to bed over the past month, I have not been sleeping. I've been wide awake in my bed. So now, because your brain is such an incredibly associative device, it learns the association that my bed is the place where I'm always awake. And what do we then do? We need to break that association in insomnia. So what we do is we say the 20-minute rule. If you've been in bed for about 20 minutes and it's just not happening for you, don't worry. Don't listen to idiots like me, that doom and gloom and disease and sickness and... One bad night is not gonna be a problem. It's just not. So just say, "Look, tonight is not my night. I am not, however, going to s- lie in bed awake." Because very quickly, my brain starts to learn the association that my bed is the place where I'm wide awake. And you need to break that association, so go to a different room in dim light, just read a book, listen to a podcast, whatever it is. And the rule of thumb is the following, only return to bed when you are sleepy. And so there's no time limit, and that way, you gradually relearn the association that my bed is the place where I always get consistent sleep. Because otherwise, it's the dentist chair. You walk into your bedroom and you look at your bed and it's your nemesis, and you've convinced yourself even before you get into bed, "I'm not going to sleep, because that's the place where I always don't sleep." And by the way, if you suffer from the 3:00 AM awakenings, my first question is, how do you know it's 3:00 AM? (laughs) And that's your first problem. Looking at the clock does two things. It makes you more anxious.
16. Yeah.
17. And second, because your brain is such an incredibly associative device, you start to then decide that 3:00 AM is the time when I need to wake up. If you keep looking at the clock, you keep reinforcing that it's three or four, and sleep at three o'clock in the morning is like trying to remember someone's name. The harder you try, the further you push sleep away. Sleep is something that happens to you, it's not something that you make happen. And so at that moment, the best advice if you don't want to get out of bed is do any one of the following. Meditation, just do a guided meditation. You can download apps. Next, if that's not your thing, that's okay. Do box breathing. You know, you can sort of inhale for five, hold for six, exhale for seven. There's all sorts of different numbers, but you can do breathing exercises. The third, if you don't like that, is a body scan. So close your eyes, start at the top of your head, feel as, y- you know, "Do I have tension in my forehead? Do I need to relax it? What about my neck? Do I need to..." Move through your body and gradually go down. "How are my shoulder blades feeling?" And just relax down into the bed, and gradually down into the chest, into the... Move through and just relax. If none of those things feel fun, the next thing you can do is take yourself on a mental walk. There's a great study from my university, uh, the University of Berkeley, California.And we didn't do this study, Alison Harvey did it. By the way, counting sheep, bad idea. Makes your sleep worse, it turns out. Why is that? Because
1:00:50 – 1:02:44
Why Counting Sheep Doesn’t Work
1. MWMatthew Walker
  well, with every kind of little bleating cotton wool ball with a strange look on its face that leaps over the fence that you're counting, you're reinforcing every minute of sleep that you're not getting. And it seems to make matters worse. But what she found was that there's an alternative. If you think about a walk that you know in great vivid detail. So for me, it's going to be walking the dog. So I go over to the shelf, I open the door, is it the red lead or the r- I'm gonna go with the blue lead today. So I clip the dog in with my right hand, open the door with my left hand and take a left down the stairs, I look a- It's that level of I want you 4K detail in terms of granularity. And what's common about every method I've just described, meditation, box breathing, m- sort of, uh, body scan, going on a mental walk, all of these things have in common that you get your mind off itself.
2. In that s- particular example where she asks you to vividly think about a journey that you know, what did she find in the study?
3. What she found is that that increases the speed with which you fall back asleep.
4. Ah.
5. Significantly. Because as I said, it- it's so, you know, her work, to me, demonstrated that it- it is so like that name because the moment I stop trying to remember someone's name, what happens?
6. (snaps fingers) You remember it again.
7. I remember it. And so when you do these types of exercises where you're getting the mind off itself, the next thing that you typically remember is your alarm clock going off in the morning.
8. Is this why people listen to very vivid sleep stories and why I listen to serial killer documentaries?
9. Serial killer documentaries?
10. True crime documentaries, I should say, that's a bit more, uh, nice to palate.
11. I don't know of them. My suspicion is that they may be doing your deep sleep
1:02:44 – 1:04:23
The Better Alternative to Counting Sheep
1. MWMatthew Walker
  a disservice. And I think that-
2. Stick up for me in the comments.
3. (laughs)
4. Guys, if you, if you listen to true crime to fall asleep, please write it below in the comment section.
5. If you find it subjectively wonderfully pacifying and calming-
6. (laughs)
7. ... and there is not death, maiming-
8. I know where I would go.
9. ... blood and limbs being distributed at high velocity all over the scene, I would say it's great. But if it looks like a Quentin Tarantino movie or sounds like one, maybe harm and fowl rather than no harm, no foul.
10. I mean, like, just in my ears.
11. But yes.
12. Yeah.
13. So, you know, we forget that to the best of my knowledge, the meditation company called Calm, now I have no f- affiliation with them. They were doing somewhat well. But what they realized is that they wanted people to sort of meditate in the morning and when they use- looked at their usage statistics, people were meditating in the morning, but then there was a huge swath of usage right before bed. People were self-medicating their state of insomnia. And then through a stroke of genius they realized, "When we were young, we used to love falling asleep to our parents reading us a story. Why is that any different when we become adults?" So they created Sleep Stories and they went from struggling as a company, I think, to becoming the first or one of the first billion dollar valuation health companies out there. They became a unicorn. And now they can, th- they've got, you know, people like Matthew McConaughey, they've got Harry Styles, and then occasionally they've got a- a, you know, an unfortunate British sleep scientist, um, with a bad voice. But you can listen to these Sleep Stories and they are wonderfully soporific. Why? Because they get your mind off itself.
1:04:23 – 1:11:34
Magnesium for Sleep: Does It Really Work?
1. MWMatthew Walker
2. We, we talked, um, earlier on about melatonin and, uh, th- there are other supplements which people talk a lot about. One of the ones that's become really popular is magnesium.
3. Mm-hmm.
4. I've heard, uh, ashwagandha and I've heard magnesium a lot.
5. Yeah.
6. Is there any efficacy to these? Are these- are these useful?
7. The first thing I would say is that if you're suffering from sleep problems and you're looking to supplement, you're stepping over dollars to pick up pennies.
8. Okay.
9. What you need to do is think about the fundamentals. Regularity, watch your caffeine intake, make sure you're not drinking too much alcohol, get regular, dim down half the lights, digital detox. Any one of those, but especially all of them combined are going to get you log orders of better sleep than reaching for the latest supplement bottle of whatever it is. The second thing to say is, think about it from a logical standpoint. If there were really some supplement that promises to be the Shangri-La of all resplendent sleep at night, the drug companies would've been all over it decades ago. To put it in context, it took George Lucas I think about 30 years to amass something like four billion in revenue from the Star Wars franchise. It took Ambien 22 months. That's how big a business sleep pharma is.
10. Ambien's what, a sleep pill?
11. Ambien is a sleep pill. Magnesium, if you dig into it, and I- I did a deep dive about three years ago 'cause I- I kept hearing it too, this magnesium, magnesium. The first thing to note is that most forms of magnesium, magnesium oxy, uh, uh, oxide or magnesium citrate, most of these forms of magnesium don't cross the blood-brain barrier (laughs) . And sleep is produced by your brain. So how can something that doesn't get into your brain affect brain process number one? There is one form of magnesium that seems to have some evidence in favor of it, it's called magnesium L-threonate. But if you look at the literature, where did this story come from? It turns out that about 30 years ago, they started looking at people who had disrupted sleep, and they would assess their blood work. And what they found is that some of those people were magnesium deficient. And when they supplemented them with magnesium and they became magnesium normative, their sleep got better.But that's very different than saying, "Look, you and I, we're currently magnesium normative," and then dosing myself with high volumes of magnesium. Am I imagining that that's going to make my sleep better? The, the analogy would be, let's say I develop this incredible new oxygen saturation machine, and you say to me, "Well, but Matt, my blood oxygen saturation right now, looking at my device, tells me it's 98.6%." It doesn't matter how fancy or good my machine is, I'm not going to get you past 100%. You're already at ceiling level.
12. Mm-hmm.
13. And that's the problem with magnesium supplementation. If you're magnesium normative, all you're doing is creating probably expensive urine at, at, at that (laughs) moment in time. Now, there may be an indirect benefit of magnesium in that it does seem to relax muscles, and when the body is in a state of relaxation, it sends a signal of relaxation back up a branch of nerves called the vagus nerve that goes up to the brain and signals to your brain you're starting to relax down, and you get this state of quiescence. And that's very helpful for sleep. So, magnesium may still have an indirect benefit on sleep through its relaxation kind of policy that it instantiates in the body, but overall, magnesium is not really moving the needle if you look at the studies. Ashwagandha is different. Ashwagandha and another compound called phosphatidylserine, phosphatidylserine and ashwagandha, both of these supplements seem to help do one of two things. They either ratchet down the fight or flight branch of your nervous system, and they can also reduce the amount of cortisol that the body is releasing. That's important, because I see a lot of people coming to the sleep center where I'm at, and they have what I call the tired but wired phenomenon, where they come to me and they say, "I am so tired. I am so, so tired, but I'm just so wired emotionally and from a nervous perspective that I can't fall asleep." And let's say that you've done, let's say, you know, um, an onstage event, and it's incredible. You've got that onstage buzz. You come offstage, until 11:00 PM, and normally you would be fast asleep, but you know you are so wired, it doesn't matter. You are tired, as tired as can be, but you're so wired you can't fall asleep. That's the fight or flight branch being switched on, and you just can't fall asleep. You need to push it back off. Phosphatidylserine and ashwagandha will both push you back over into the more quiescent, what we call parasympathetic nervous system branch. That's good. However, they also will reduce cortisol, and cortisol is a wake promoting hormone. Cortisol is fine. We... It gets a bad rap. You need to have your cortisol start to spike a few hours before bed, and it helps with the waking up process. It's wonderful. Every day, we have a cortisol spike that starts happening before we wake up. It's one of the things that helps us wake up, and then it builds us to this beautiful crescendo mid-morning, where you should be awake and not needing caffeine.
14. And it drops before bed.
15. And then it starts to peak in the sort of l- middle early afternoon, and in fact usually peaks at the late morning hours, I should say. And then it will start its awesome sort of downswing, and what you see is that right before you go to bed, cortisol should hit its lowest point, what we call its nadir, its lowest trough.
16. Mm-hmm.
17. What's interesting, by the way, just as an aside, is that insomnia we can classify usually as at least one of two different types. There's actually multiple, but let's just say there are, uh, of those multiple, there are two types. One is called sleep onset insomnia, "I can't fall asleep." The other is sleep maintenance insomnia, "I can't stay asleep." When they've looked at people's cortisol on a 30-minute by 30-minute basis on the 24-hour clock face, we go through just what we described. Just before we wake up, we get this rise in cortisol. It peaks late morning, and then it drops down, and right before bed, our cortisol is almost at its lowest point. With insomnia patients, they show exactly the same thing, a beautiful rise in the late morning hours. It starts to come down, but then you see two anomalies. Right before bed, it goes back up, and then in the middle of the night, even when it's starting to rise, it will have this abnormal spike right in the middle of the night, too. And what we believe is that that may in part explain sleep onset insomnia. Cortisol should be coming down, and it should stay low right before we go to bed, but then it jumps back up in insomnia patients. "I can't fall asleep." And then, it continues to stay low throughout the first half
1:11:34 – 1:13:20
Ads
1. MWMatthew Walker
  of the night, but then it also spikes in insomnia patients. "I can't stay asleep."
2. I've had so many founders speak to me and say, "Why didn't this particular ad that I ran on this platform work for me?" Maybe the copy wasn't good, the creative wasn't strong, but usually the problem is they're not having the right conversation, because that ad never reached the right person. And if you're in B2B marketing, that is much of the game, and this is where LinkedIn Ads solves that problem for you. Their targeting is ridiculously specific. You can target by job title, seniority, company size, industry, and even someone's skill set, and their network includes over a billion professionals. About 130 million of them are decision-makers. So, when you use LinkedIn Ads, you're putting your brand in front of the right people. And LinkedIn Ads also drive the highest B2B return on ad spend across all ad networks, in my experience. If you wanna give them a try, head over to linkedin.com/diary, and when you spend $250 on your first LinkedIn Ads campaign, you'll get an extra $250 credit from me for the next one. That's linkedin.com/diary. Terms and conditions apply. We were talking about regularity, timing all these things, and quality and quantity, but one of the things I learned from your work is that that last hour is...... potentially the most important hour of me being in bed. And I, I say this in part 'cause my, my girlfriend, she would wake, she would have about six, six hours, six and a half hours sleep. She sleeps very, very well, perfect sleeper, but she'd always get up really, really, really early. And in part, that was because of th- the guilt that I talked about. But I had a conversation with her a- about the guilt, and I said, "Just stay in bed as long as you need to stay in bed. Like, just have that extra eighth hour." And in part, that's because I learnt that the further we go in sleep, the more REM
1:13:20 – 1:20:17
How REM Sleep Works and How to Maximize It
1. MWMatthew Walker
  we're getting.
2. Yeah.
3. Okay, can you explain that to me with these four blocks-
4. I'd love to.
5. ... why that last hour is particularly important and why we shouldn't be jumping out of bed, or w- why we should be using certain sleep devices to wake us up when we're at the end of that last hour of REM?
6. Absolutely. So here we have the four blocks of sleep. So when we first fall asleep, we go into light non-rapid eye movement sleep, stage one. This is the stage of sleep that if I wake you up out of it, you say, "I, I wasn't sleeping."
7. Mm-hmm.
8. Now y- it's just that you're just in that transitional phase, this beautiful liminal state between the windows of wakefulness and true sleep. So this is your bridge between the waking world and the sleep world, and it doesn't last for very long, maybe just 10 or 15 minutes at tops. Then you get into the workhorse of sleep. This is stage two non-REM sleep. 50% of your night is spent in stage two non-REM sleep. I don't like the word light non-REM sleep. I've often used it, but it's not really, it's w- we do a lot of cognitive processing in stage two non-REM sleep. It's good stuff. It's not just the stage that you have to go through from sort of, you know, deep non-REM sleep to go back to stage two in order t- for you to get to REM, but I'll come to that. So we have fallen asleep, 10 minutes.
9. 10 minutes, yeah.
10. Now we're in stage two non-REM sleep. We'll stay there for about 15 or 20 minutes. Then if it's in the first couple of hours of the night, we go down into the very deepest stages of deep non-REM sleep. This is where the brain wave patterns slow down, but the brain waves become incredibly big, huge, big, powerful, slow brain waves. This is where you get an enormous amount of restoration and recovery of many of your major physiological systems. Then-
11. So physical recovery?
12. Physical recovery, but mental too.
13. Yeah.
14. It's during deep sleep that you take newly minted memories that you've learned and you hit the save button on those memories so that you don't forget.
15. Mm-hmm.
16. Deep sleep essentially is going to future proof the information that you just learned today. It transfers information from a short term storage vulnerable reservoir to a more permanent long term storage site. It's during deep non-REM sleep when we have this communication. So think of those deep, powerful, slow brain waves like long wave radio station, when you used to tune into a radio station in the car. You get huge ability for information transfer across long distances, across huge paths in the brain. It's amazing. So we've gone from light non-REM, then we go down into deep non-REM. We'll stay there for about 15 or 20 minutes. Then we'll start to rise back up again. We'll go back into stage two non-REM sleep.
17. Wait, w- we've gone from one, two, three to two?
18. Yes. So we've gone, think about it more almost like a roller coaster ride. So we go from light non-REM, and then we go down into stage two non-REM-
19. Yeah.
20. ... then we go down into deep sleep, and then we're going to rise back up into light stage two non-REM sleep. We're going to stay there, and after about 70, 80 minutes, you're going to pop up pfft and you'll have a short REM sleep period.
21. Oh, okay, like this.
22. And this is beautiful. So this is what we call a hypnogram.
23. I'll put this on the screen for anyone.
24. Lovely. So what I'm describing here is this roller coaster ride. So we've fallen asleep, light stage one non-REM, go down into stage two, then you go down and you have a heavy period of deep non-REM slow wave sleep, stage three, and then, and that's what you see on your sleep tracker as deep sleep. This is light sleep, this is deep sleep. Stage two non-REM sleep, light sleep, stage three non-REM sleep, deep sleep. But then you'll start to climb back up, and then you may pop up and you'll have a short REM sleep period here after about 70 or 80 minutes. So you'll have about 10 minutes of REM sleep, and then back down you go again. You go down into non-REM sleep, and then up into REM, down into non-REM sleep, and you'll go up into REM, down into non-REM sleep, and up into REM. So what's interesting, however, is that the ratio of non-REM to REM changes. Now there's a myth out there and it's a bit of a problem. We humans have a 90 minute average non-REM to REM cycle. So we go down into non-REM sleep and then up into REM sleep every 90 minutes, then we go back down into non-REM sleep and then up into REM sleep. So we go down into non-REM sleep and then up into REM in this 90 minute cycle. The problem is that it's on average 90 minutes. It ranges from 70 minutes to, to 120 minutes from one individual to the next. So you know these devices that you may have seen tried to sort of, you know, entrepreneurship, they say, "I'm going to wake you up at the ideal moment in your 90 minute cycle so that this thing that sits on my bedside, I tap it when I'm, the lights go out, and then it's going to go on its 90 minute cycle and it's going to figure out the perfect moment to wake you up." It's nonsense because my sleep cycle may be 75 minutes, yours may be 105 minutes. It's got no idea 'cause it's using a hard-coded 90 minute cycle. It's- it's in some ways nonsense. But we go down into non-REM sleep and up into REM sleep every 90 minutes. What changes however is the ratio of non-REM to REM within those 90 minute cycles as you move across the night such that in the first half of the night, the majority of those 90 minute cycles are comprised of lots of deep non-REM sleep and very little REM sleep.But as you push through to the second half of the night, now that seesaw balance shifts over and you spend much more of your time in REM sleep in the second half of the night, and particularly, just as you said, in the last two hours of the night. Why is this consequential? Well, just as you said and you spoke about for your girlfriend, let's say that, you know, I normally go to bed, for argument's sake, and I'm not saying this is the ideal time, but I go to bed at midnight to make the math easy, and I wake up at 8:00. But tomorrow, I've got to catch my flight back home, so I'm going to wake up two hours early, so I'm going to wake up at 6:00 rather than 8:00. I've lost two hours of sleep. So how much total sleep have I lost? Well, I've lost 25% of my total sleep, two hours of my eight hours, 25%. Well, yes and no. I've lost 25% of my total sleep, but I may have lost 50, 60, 70% of all of my REM sleep. Why? Because REM sleep comes in the second half, and particularly those last couple of hours of sleep. So that's why it's not just academic that you understand the sleep cycle relationship, but it's also pragmatic because it can impact the amount... In fact, the easiest way if people said, "How can I get more REM sleep?" I would say, "Just sleep 15 minutes later into the day than you normally would do and you will disproportionately bias yourself towards getting significantly more REM sleep."
1:20:17 – 1:21:54
Why REM Sleep Is Important
1. MWMatthew Walker
2. SBSteven Bartlett
  And why does REM sleep matter?
3. MWMatthew Walker
  REM sleep is a brain state, firstly, that is incredibly active. In some... in fact, some parts of the brain, particularly if I were to show you these deep emotional centers of the brain, as I pull this brain apart, so we've got these sort of deep emotional centers in the brain that sit, and in fact, they're sort of, they're more just underneath in here, tucked in-inside, just next to your brain stem at the top of it. And these emotional centers are called the amygdala and you have one on the left and one on the right side of your brain. That part of the brain, together with the memory structure that runs alongside it called the hippocampus, those two parts of the brain form what we call the limbic system, and you may have heard of the limbic system. It's, uh, the emotional centers of the brain. Those can be up to 40% more active when you're in dream sleep than when you're awake.
4. SBSteven Bartlett
  Dream sleep?
5. MWMatthew Walker
  Dream sleep is rapid eye movement sleep.
6. SBSteven Bartlett
  REM sleep.
7. MWMatthew Walker
  So REM sleep is the stage... Now, it depends on how you define dreaming. If you define dreaming as any mental activity reported upon awakening, then you dream in all stages of sleep, light non-REM sleep, deep REM sleep. So what would, what would that sound like? Well, if I woke you up and said, "Steven, just tell me what was going through your head," and you said, "Well, I was just thinking about the next time you're going to come in and wake me up," that's just a dream thought. Wha- most people think of dreams as the dreams that we have from REM sleep, from rapid eye movement sleep. That's why we call it dream sleep. Dreams from rapid eye movement sleep are florid, they're narrative. In fact, last night when you fell asleep and you went into dream sleep, you became incredibly psychotic.
1:21:54 – 1:24:51
Entering a 'Psychosis' State During Dreams
1. MWMatthew Walker
2. SBSteven Bartlett
  Excuse me?
3. MWMatthew Walker
  Now, before you reject my diagnosis of your nighttime psychosis, let me give you five good reasons. When you went into dream sleep last night, you started to see things which were not there, so you were hallucinating. Second, you believed things that couldn't possibly be true, so you were delusional. Third, you became confused about time, place, and person. So in psychiatry, we call that being disorientated. Fourth, you had wildly fluctuating emotions, something that we call being emotionally labile, you're all over the place. And then, how wonderful, you and I, 'cause I include myself now as being psychotic, you and I, we both woke up this morning and we forgot most, if not all, of that dream experience, so we're suffering from amnesia. If you were to experience any one of those five symptoms whilst you're awake, you'll be seeking some degree of psychological help. But for reasons that we're only now understanding, it seems to be a normal biological and psychological process. So what are the reasons? Why do we dream? We dream for at least two different reasons. The first reason is emotional first aid. REM sleep is what I've defined as overnight therapy, and it's during dream sleep where your brain takes difficult, painful emotional experiences and it acts like a nocturnal soothing balm and it just takes the sharp edges off those difficult, painful experiences so that you come back the next day and you have a memory of an emotional event, but it's no longer emotional, y- you don't have that same visceral regurgitation of, of that same emotional charge. Why is REM sleep able to do this overnight therapy, this depotentiation? Why is REM sleep able to sort of strip the bitter emotional rind from the informational orange, as it were? The reason is the following. Dream sleep, REM sleep, is the only time during the 24-hour period where the brain shuts off a stress-related neurochemical called noradrenaline. Now, you've heard of the sister chemical downstairs in your body called adrenaline. Well, upstairs in the brain, we don't have adrenaline, we have noradrenaline. REM sleep is the only time where it's completely shut off. And what we put forward is a theory called overnight therapy, where your brain has, as I told you, these emotional centers and these memory centers, the emotional centers, the amygdala, the memory centers, the hippocampus, you reactivate those structures when you go into dream sleep. So your brain gets the chance to reactivate and replay and reprocess emotional experiences. However, it's doing it in a, quote-unquote, "safe neurochemical environment" because that stress chemical of noradrenaline is completely shut off. So it's the ideal neurochemical therapy for stripping the emotion from the memory. And we put forward a theory that perhaps the quintessential disorder where this fails
1:24:51 – 1:30:58
Rewriting Trauma Through Dream Healing
1. MWMatthew Walker
  is PTSD, because when you speak to those patients, not only do we see that their REM sleep is disrupted-... when you speak to those patients, they will say, "Look, I just can't 'get over the event.'" What they mean by that is the war veteran who is now going to the supermarket and they come outside, and they're in the car park, and the car backfires, and they instantly have the flashback to the, the sort of detonation on the military field. And what's happening there is that the brain has not stripped the emotion from the memory, so every time they relive the memory, they regurgitate that same emotional reaction.

Episode duration: 2:17:26

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Intro

Sleep Changes Your DNA

The Stigma Around Sleep and Laziness

What's Stopping People From Sleeping?

The Shocking Link Between Weekend Sleep-Ins and Heart Disease

New Research: Sleep Banking for Low-Sleep Periods

Boost Cognitive Performance With This Sleep Hack

3 Ways to Instantly Improve Sleep Quality

It's Not Blue Light That's Keeping You Awake

Melatonin Doesn’t Make You Sleep – Here's What It Does

How Much Melatonin Is Right?

The 1% With a Nocturnal Clock Who Can't Sleep Until 3 AM

Is Melatonin Really the Magic Sleep Pill?

The Trade-Offs of Sleep Medication

The Key to a Digital Detox

The 4 Macros of Good Sleep: QQRT

The Minimum Sleep Needed to Stay Alive

How Sleep Regularity Predicts Life Expectancy

Try This 7-Day Sleep Enhancer Challenge

How to Tell If Your Room Is Dark Enough for Sleep

Why Counting Sheep Doesn’t Work

The Better Alternative to Counting Sheep

Magnesium for Sleep: Does It Really Work?

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How REM Sleep Works and How to Maximize It

Why REM Sleep Is Important

Entering a 'Psychosis' State During Dreams

Rewriting Trauma Through Dream Healing

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