The Wellness Scoop - Why We Sleep with Matthew Walker

Episode Date: June 18, 2019

Why do we sleep, how much does it matter, how much sleep do we really need, to what extent do lifestyle factors like coffee, alcohol and technology affect our ability to sleep? Today we’re talking to Matthew Walker, the award winning author of bestseller ‘Why We Sleep’ about sleep, getting to grips with our sleep cycles, the connection between sleep and our mental and physical health, how to sleep better and why we need to make it a priority. See acast.com/privacy for privacy and opt-out information. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Visit BetterHelp.com today to get 10% off your first month. That's BetterHelp, H-E-L-P.com. Hi, and welcome back to the Deliciously Ella podcast with me, Ella Mills, and my husband and business partner, Matthew Mills. Hi, everyone. So today we're talking about sleep, how, and my husband and business partner, Matthew Mills. Hi, everyone. So today we're talking about sleep, how it impacts our mental and physical health, why we need it and what it actually does. I'm sure most of you have seen the book, Why We Sleep Somewhere. It's been the number one bestseller across the world. And we're honored to have the author Matthew Walker as our guest today.

So Matthew is kind of the ultimate leader, I think, in this space. I don't know about that, but it's a delight and a privilege to be here firstly, by the way. Thank you so much for having me on. My pleasure. So I got your book last year and it fascinated me. I mean, I'm fascinated by anything in the health and wellbeing space, but sleep is obviously something that's so relevant to every single person, no matter what stage of life you're at. And I was a really interesting stat that I wanted to start with that you said two thirds of adults in developed nations failed to obtain the recommended eight hours of sleep. So if you're listening to this and thinking I

struggle with sleep, or I'm not getting enough sleep, you are not alone by any means. And I wondered if we could start kind of right at the beginning go really really back to basics and just understand effectively what is sleep so you know we used to ask the question you know why do we sleep or what is sleep good for and the crass answer used to be that we sleep to cure sleepiness which is just an idiotic answer it's like saying I eat to cure hunger it tells you nothing about the nutritional benefits of food now based on the weight of the evidence, we've actually had to upend the question and ask, is there any process in your body or 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 no.

And so I think in response to your question, you know, what is sleep or why do we need it? Sleep is essentially your life support system. It is Mother Nature's best effort yet at immortality. And I think sleep is essentially the Swiss army knife of health. You know, no matter what your ailment, sleep has a tool in the box that it probably can help out with. And so you hear a lot about sleep cycles and REM and, you know, there's a lot of apps and things out there trying to help us track. Can you tell us about what's happening while we sleep, those different cycles and what happens during that and what we need to be thinking about? Yeah, so human beings actually have two types of sleep. One is called rapid eye movement sleep or REM sleep.

The other is called non-rapid eye movement sleep or non-REM sleep for short. And non-REM sleep has been further subdivided into four separate stages, unimaginatively called stages one through four, increasing in their depth of sleep. So stages three and four are those really deep restorative stages of sleep. And then on the other hand, we have, as I mentioned, rapid eye movement sleep. That's the stage in which you dream. So let's think about what happens when you put your head on the pillow and you start to fall asleep. You start to enter into light, non-rapid eye movement sleep, like sort of stages one and two non-REM sleep. And then you'll go down and you'll go into deeper

non-REM sleep. And then after about 60 or and you'll go into deeper non-REM sleep. And then after about 60 or 70 minutes, you'll start to rise back up and you'll pop up and you'll have a short REM sleep period. And then back down, you go again, down into non-REM, up into REM. And you do that throughout the entire night. And it's a 90 minute cycle. So down into non-REM, up into REM every 90 minutes, at least in humans, it's different for different. And how long is the REM period where you can dream? Great question. So it turns out that those two types of sleep will play out in a battle for brain domination throughout the night. And that sort of cerebral war is going to be won and lost every 90 minutes. But what changes 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 composed of lots of deep, dreamless sleep. But as you push through to the second half of the night, that balance shifts and now you have much more rapid eye movement sleep. So in other words, you're far more likely to have your dream sleep in the second half of the night. You won't have very much in the first half. That's when you get most of your deep sleep. And is one more restorative than the other? No, it turns out that every single stage of sleep seems to provide some type of beneficial function. Okay. And in some ways it sort of makes sense that you would think, well, sleep on the one hand

is the most idiotic invention. You're not eating, you're not finding food, you're not protecting your young, you're not finding a mate, you're not reproducing. Worse still, you're vulnerable to predation. On any one of those grounds, sleep should have been strongly selected against in the course of evolution. But sleep has persisted, heroically so. And if you were to think that Mother Nature could have said, well, one of these stages isn't really important, she would have done away with it hundreds of thousands of years ago. So everything that we've got now is absolutely essential. And are sleeping patterns in human beings similar? Have they remained similar over time? Or do we sleep more now or less now than we used to?

Overall, our total amount of sleep has decreased dramatically over the last 100 years. So back in the 1940s, there was a survey done that demonstrated the average adult was sleeping 7.9 hours a night. Now, in the United Kingdom, that number is down on average to 6,049 minutes. In America, it's 6,032 minutes. In America, it's 6,032 minutes. In Japan, it's 6,022 minutes. So in other words, in the blink of an evolutionary eye within the space of 100 years, we've lopped off 15 to 20% of this essential biological need that we call sleep. What are the known impacts of that? Every major disease that is killing us in the developed

world has significant and many of them causal links to a lack of sleep. So I'll just give you two examples. The two most feared diseases throughout developed worlds, Alzheimer's disease and cancer, both have causal links. And for Alzheimer's disease, when you go into sleep at night, particularly deep sleep, the brain has a sewage system and it's a cleansing process. And that sewage system kicks into high gear during deep sleep and it washes away all of the toxic metabolic byproducts that have been building up throughout the day. So it's essentially good night, sleep clean in that way. And one of the toxic proteins that it removes is something called beta amyloid,

which is this protein that is linked to Alzheimer's disease. So every night that you're not getting enough sleep, you're increasing your risk for the development of that protein buildup and therefore increasing your risk for Alzheimer's disease. And what is a good amount of sleep? So the range right now is seven to nine hours with a sweet spot of about eight for most people. There is a range. Some people can sleep even more than that. They may have, you know, a 10 hour, 11 hour need, maybe even 12 hour need. And how do you know what your need is? It's a very good question. So firstly, one of the things you can do is say, if I set an alarm and the alarm didn't go off, would I sleep past that time?

Yeah. And if the answer is yes, you're not getting enough sleep. Because one thing I think you come across quite often is this idea that we should keep a pretty consistent sleep pattern where we're waking up around the same time every day. Is that something that also benefits us a lot? It benefits us hugely. And I think if there was one tip I would give everyone for sleep, it is regularity. So go to bed at the same time, wake up at the same time, no matter whether it's the weekday, the weekend, even if you've had a bad night of sleep,

still wake up at the same time, go throughout the day, it's going to be a tough day, but get back into set in the evening. Because our bodies are designed to revolve around regularity that's how we evolved regularity sort of will anchor your sleep and it will improve the quantity and the quality of that sleep so you're absolutely right regularity is king when it comes to sleep and what about napping i was just about to ask that exact question because i loves to nap more than anyone i've ever met i love my sat Saturday afternoon is I just love getting curled up on the sofa usually with football on or golf on and having a good two-hour nap so is that is that good or is that bad well naps can be a double-edged sword and the advice is this if you are struggling with sleep at night or you can't nap regularly

then you should avoid naps okay but if you don't struggle with sleep at night or you can't nap regularly, then you should avoid naps. But if you don't struggle with sleep and you can nap somewhat regularly, then naps are just fine. But let me come back to the first point to explain that. As you're awake throughout the day, there's a chemical that builds up called adenosine. The more of it that builds up, the sleepier you feel. And after about 16 hours of being awake, you should have a good healthy weight of sleepiness in the brain so that you fall asleep and you stay asleep. And when we sleep, we remove all of that sleepiness from the brain. But if you take a nap, especially in the afternoon, it's like the pressure cooker analogy. So you release the valve and some of that sleepiness goes away during the nap. And therefore, when it comes time to fall asleep at night, you're not as sleepy anymore. And

therefore you struggle to fall asleep or you wake up and you can't get back to sleep. That's not the case with everyone. But if you do struggle with sleep and you have sort of issues with insomnia, you should not nap during the day. So I wanted to, if it's okay, kind of go back to the health implications of sleep deprivation. I guess the first question is what constitutes sleep deprivation? So there are all different flavors of insufficient sleep. What we know is that once you get below seven hours of sleep a night, we can measure objective impairments in your brain and your body. So at seven hours or below, that's termed either partial sleep reduction, and then the less and less you go, you move towards total sleep deprivation. And one of the problems with a lack of sleep,

and it is a real problem, is that you don't know how badly you're suffering when you're sleep deprived. So the analogy would be a drunk driver at a bar, you know, they've had a couple of pints and they pick up their keys and they say, look, I'm fine to drive home. And your response is no, I know subjectively you think you're fine to drive, but objectively you're not. And it's the same way with a lack of sleep. Your confidence in how well you think you're doing far exceeds actually your performance in terms of impairment, as well as your body's sort of decimation of physiological function as well. And is that something that, say you have a big night out on Saturday and you don't sleep very much, if you do it once it's kind of okay, but

if you build it up over time, it has a bigger impact or does it have a big impact on us each time that we miss sleep? Unfortunately, it has a big impact even after one night. So I'll tell you about one fascinating study. There's a group of cells in your body, immune cells called natural killer cells. And you can think of them almost like the secret service agents of your immune system. They're very good at identifying dangerous, unwanted elements and eliminating them. And one of the things that they will destroy are cancer cells. And every day, all of us, we have cells that are cancerous in our bodies. But what stops those cancerous cells from becoming the disease that we call cancer is these natural killer cells. So they're a critical part of your immune system. If you take a group of individuals and you limit them to just four hours of sleep for one night, you see a 70% drop in natural killer cell activity. That is an alarming state of immune deficiency. And it happens after just one bad night of sleep, essentially one short night of sleep. Are there things that you should avoid during the day so that you can make sure that you can sleep well at night?

There are, and these are probably going to make me a little bit unpopular. I mean, I'm generally an unpopular person to begin with, I should say, but these make me even more unpopular. Caffeine and alcohol, they're probably the two most misunderstood chemicals when it comes to sleep. Firstly, everyone knows that caffeine will keep you awake. It makes you more alert. But the problem with caffeine is that it has a long duration of action midnight. So a cup of coffee with lunch is essentially like getting into bed at night at midnight. And just before you turn off the light, you swig a quarter of a cup of coffee and you hope for a good night of sleep. It's not going to happen. And so you have to be careful with caffeine. Try to cut it off 12 to 14 hours before you expect to go to sleep. That's a good rule of thumb. So it's a breakfast thing. If you like it

in the morning to help wake you up, firstly, just ask, do you really need it? And if you do, that's another one of those signs that you're not getting enough sleep. Because if you're having caffeine, first thing when you wake up, you're probably self-medicating your state of sleep deprivation. So in general, would you just say don't drink caffeine? Well, I think people can certainly have a couple of cups of tea or coffee in the morning. But again, try to start to cut off the caffeine intake by about 10 o'clock in the morning. Let's say if you've woken up at 7, because that will give you enough time to sort of get fully caffeine free and ensure the best night of sleep. The other danger with caffeine, some people say, well, I can have a cup of coffee with dinner and I fall asleep and I stay asleep. So there's no problem. That's not true because if you give someone a single dose of coffee in the evening,

let's say 180 milligrams of caffeine, you decrease the amount of deep sleep that they have at night by about 20%. For you to sort of put that in context, for you to have a reduction of 20% of your deep sleep, I would have to age you by about 20 to 25 years. Or you could do it every night with a cup of coffee after dinner. So I think caffeine is one of the things that you can avoid during the day to ensure good sleep. Still take it in the morning, but just be mindful in the afternoon and especially in the evening.

And what's fascinating about the studies, people will say, well, I perform better when I have caffeine. That also is a myth. It turns out that the more and more you have caffeine, your performance essentially when you don't have caffeine, when you're addicted is just going down and down. And people medicate that performance decrement with caffeine to get them back to where they would be naturally. So essentially what you're feeling when you're having caffeine is you getting over your addiction and your dependency on caffeine. You're not actually getting any better. You're just getting back to where you were. wired and tired that I felt like I needed sleep. I felt like I could sleep, but for some reason, sort of, I was just too wired and it was the caffeine. So if it's three o'clock in the afternoon and you're just feeling really tired, it's that

classic time where you're like, oh, I'll just have a cup of coffee and it'll just give me that little boost to get me through the afternoon, which I'm definitely guilty of. What's the best thing to do at that point instead? So there are several things you can do. Firstly, move, get physically active. If it's just stand up and walk around the office building for two minutes at a fast pace, do that. Get some daylight and fresh air. That's a great help for waking you up. You can still have a hot drink because as your body temperature increases, you become more awake. As your body temperature drops, you go more towards sleep. And so as you're starting to get drowsy in the afternoon,

it's probably because your body temperature is starting to drop a little bit. So have a hot drink, just make it decaffeinated, have a herbal tea, something along those lines. So I think the key with caffeine is don't completely stop.

Substitute rather than exclude so start drinking something else that's non-caffeinated rather than just not drinking anything at all yeah obviously there's caffeine and things other than coffee i'm sure coffee will be what most people have got in their mind right now but you obviously have like elements of caffeine and chocolate for example is it that if you have a little bit of chocolate in the afternoon is there enough caffeine and something like that to have an impact or is that more okay it depends on the chocolate and you have a little bit of chocolate in the afternoon, is there enough caffeine in something like that to have an impact? Or is that more okay? It depends on the chocolate.

And you have to sort of be a little bit careful of that. But for the most part, you know, if you have a segment of chocolate and it's a type of chocolate, usually milk chocolate tends to have less caffeine than dark chocolate, then it's probably not going to hit you with that same wired nature that a medium cup of coffee would have. But just test it out yourself. Track it.

Say, you know, on every afternoon when I had a piece of dark chocolate, did I struggle with sleep at night? And can I see that pattern? And if that pattern is there, then maybe I should abstain. So will you tell us about alcohol as kind of point two? So alcohol is probably the most misunderstood sleep aid in inverted commas, and it's not an aid at all. Alcohol is a class of drugs that we call the sedatives and sedation is not sleep. But when people have a nightcap in the evening, they mistake the former for the latter. And you think that it helps you fall asleep faster, but you're just knocking out your cortex with the alcohol. And that's very different. The second problem with alcohol is that it fragments your sleep. So you wake up many more

times throughout the night. And then in the morning, you don't feel restored by your sleep. You don't feel refreshed. The final problem with alcohol is that it's very good at blocking your dream sleep, your rapid eye movement sleep, which is essential for a collection of functions, including sort of mental health and mood. That's where dream sleep is especially important. And if you're not getting that because you've got alcohol in the system, then you're going to be struggling with your sort of emotional. REM sleep is emotional first aid, and you need it every night, but you will block it by way of alcohol. Is alcohol or coffee, is one worse than the other? They both have their harmful impacts.

So alcohol will target rapid eye movement sleep. Caffeine will actually target deep sleep. Is a glass of wine at lunch then better than a glass of wine at dinner? It is. So, you know, the politically incorrect advice I would give that I would never speak on a public podcast would be that you should go to the pub in the morning and that way the alcohol is out your system by the evening and there's no harm,

no foul, but I would never suggest that. Yeah, so really it's vodka at breakfast. Espresso martini for breakfast. So there's a few other lifestyle factors that our listeners had questions on. Stress, exercise, technology and that kind of conversation around blue lights and diet. And I'd love to understand how those four factors also contribute or potentially harm sleep. Yeah, great question. So let's just start with stress. I think the leading cause of insomnia for most people right now is stress and anxiety. And the reason that it causes problems with sleep is that when you're stressed or you're anxious, there's a branch of your nervous system called

the fight or flight branch of the nervous system that gets pushed into overdrive. And when it's switched on, you can't fall asleep because for you to effectively fall asleep, you have to turn off that part of the nervous system. And it ultimately leads to the release of chemicals like cortisol, which is sort of a very activating hormone. It results in things like noradrenaline being released in the brain, which is a chemical that's very similar to adrenaline in the body. It has the same impact on the brain to make you alert. So there are really two recommendations when it comes to stress and sleep. Firstly, try to just sit down and identify what is it that's stressing me out? Is it work? Is it relationships? Is it family? Is it finance?

And try to think through that and then address the stress in your life. Because otherwise you're just going to, if you're sort of using sleeping pills or alcohol to get to sleep at night, that's simply just sticking a Band-Aid over the wound. It's not really going to address the real problem. The other great tool that people have used is meditation. And we've looked at some of these studies,

we've done some ourselves. Meditation is another great thing that will actually help shift you from that active branch of your nervous system over to sort of the quiet, restful branch of the nervous system, which is necessary for sleep. So people who are stressed, try playing around with meditation. There are some great apps out there like Headspace or Calm, and it helps shift you from this state where when your head hits the pillow all of a sudden you're filled with this rolodex of anxiety all of the stress and the worries what didn't i do what should i have done what do i need to do next what's coming up tomorrow

that's the last thing that you should be thinking about when your head hits the pillow it's the enemy of sleep and meditation helps you stop focusing on all the things that you're going to ruminate over or catastrophize. And it just helps you focus on your body, on your breath, and it quietens the nervous system down. That's another great tool for managing stress. Yeah, I find it so helpful. We've been, I'm pregnant, and we've been doing hypnobirthing in preparation for it. So I've been doing a lot of the kind of visualizations and meditations before bed. And it's unbelievable how well they help you sleep

because your mind goes off into the most incredible place and you drift off into the sleep and it's so much deeper. And it's a quiet sleep. It's sort of almost like a thick sleep. And one of the other tools that people have found that's quite efficacious with stress is one hour before bed or even a little before that, just get a pad of paper and a pen and just write down all of the things that are on your mind. It's catharsis. It's sort of essentially like almost vomiting out your anxiety onto the page. And when it's down there, it's out

and it's not going to stress you out as much. And studies have found that that actually decreases the amount of time that it takes you to fall asleep by about 50% 5-0. So you fall asleep in half the time when you're journaling out all of those worries. And how about food in the evening? What foods are good to eat in the evening, which aren't so good? And how long before you go to sleep should you try and finish your dinner? time-restricted eating or time-restricted feeding. And the reason is because if your intestinal systems in your digestive tract are working very hard with a big meal, and then you try to fall asleep, that sleep is not going to be as deep. It's going to be more fragmented and it's going to be more restless sleep. I should say though, however, you shouldn't go to bed hungry, but you shouldn't

go to bed packed full. So somewhere in between those two, if you need a light snack before bed, that's okay too. Try to stay away from heavy hitting carbohydrates and also sugary meals or sugary beverages. The sugar is a problem because it will actually warm your body up. So as the sugar is being metabolized, it releases energy. That energy is converted into heat. Why is that a problem? It's a problem because we need to drop our core body temperature by about one degree Celsius to initiate sleep and to stay asleep. And it's the reason you will always find it easier to fall asleep in a room that's too cold than too hot.

I don't drink a huge amount. I'd like to have a glass of wine in the evening every now and again, like maybe two evenings a week I'll have a glass of wine. And I'd probably drink coffee in the afternoon. Like, I'm genuinely, I'm going to stop. This is, it's really, when you hear it so powerfully, it properly provokes a change within you. Now I'm like, I'm not doing it. I'm just not going to do it. It really is incredibly powerful. So thank you. You're very welcome. I think, you know, sleep is the very best life insurance policy that you could ever wish for.

And when some people ask me, well, how much do I sleep? And I'll say, I'll give myself a non-negotiable sort of eight hour opportunity. And it's not because I want to be some poster child for my mission, even though I am on a mission to try to reunite humanity with the sleep that it's so desperately bereft of. It's simply because I know how critical sleep is for increasing my lifespan and increasing my health span. And so for me, it's a purely selfish act.

You know, I don't want to die any younger than I have to. My family, for example, has a history of cardiovascular disease. And deep sleep is the very best form of blood pressure medication that you could ever wish for. So I get plentiful sleep, not, as I said, sort of, you know, to champion my cause, but purely from a selfish perspective for health. And if you fly across the Atlantic and naturally there's a shorter window to sleep, how do you spend that next day and how do you adjust quickly so it's only one night that you're losing, even though we know that night is damaging in its own right? I will usually try to not sleep too much on the plane. So I just did this trip. I live just outside of San Francisco in America and I just flew over a couple of days ago into London.

And I try not to sleep too much on the plane, maybe just three or so hours. And the reason is because I want to then wake up at roughly the same time that everyone in London is starting to wake up. And then I want to have a whole day of good, healthy wakefulness to build up all of that good, healthy sleepiness. So that then that first night, which is usually the hardest night with jet lag, I'm so tight and I try to last out as long as I can. You know, I probably could fall asleep at seven o'clock in the evening, but I push through until about nine o'clock in the evening. Then I fall asleep. I have a good, long sleep. And if you get a good sleep the first night after traveling, that really helps reset your body clock. Whereas if you take too much

sleep on the plane or you arrive and then you have a nap, just as we spoke about, that's going to take away from some of that healthy sleepiness. And then you're going to really struggle with sleep at night. So that's one of the key things. The next is get lots of daylight. So as soon as I land, I usually sort of get myself settled and then I'll get outside. I'll have a run. I'll go for a walk. But I make sure that I get daylight. And when I go outside, I don't wear sunglasses because you want that light to get into the brain as much as possible because that will help retrain your body clock.

It's sort of light is like the fingers on a wristwatch dial. It just sort of helps pop out the dial and it will start resetting your sort of internal 24-hour clock. And then the final thing is start to try to eat at the same time when everyone else is eating in the new time zone. Because food is just as powerful a resetting trigger as daylight is. You can help treat some of the aspects of jet lag, but you can't cure it because we were never designed to be fast forwarded in time with this thing called a jet engine. And our biology just doesn't do well with it. So how about exercise? I know you just mentioned when you're kind of jet lagged or struggling with adjusting your sleep patterns, a run or a walk will be something

that you do. Is that solely for the benefit of getting the daylight or is that also because exercise has an impact on our sleep? Yeah, it's both of those things actually. So firstly, it's a great way to sort of just get outdoors and it gives me a purpose to be outdoors. But the second is that we know regular exercise or just physical activity, even, you know, brisk walks for 30 minutes a day, that can actually help deepen the deep quality of sleep that you get at night. What we've also found, however, is that yes, exercise helps sleep. But when we actually looked at these analyses and the data and we reversed the analysis, we found an even more powerful link, which was that if you get good sleep at night, you're firstly far more likely to be motivated to exercise. When you do exercise, you exercise more

intensely. And third, your risk for injury when you're exercising is dramatically lower when you're getting a good night of sleep so it's a two-way street exercise helps sleep but sleep is fantastic for helping exercise and in fact that's why i work with a lot of professional sports teams and individual athletes sleep is probably the greatest legal performance enhancing drug that few athletes are abusing enough of. Is there a time of day that you think is better to exercise? It really depends on what type you are. And when I say that, what I'm speaking about is something called your chronotype. Are you a morning type or are you an evening type? We call them owls and larks. Now, you don't get to decide that. It's genetically hardwired from the moment you are born.

How do you know which one you are? So a good example would be to say, you know, if you were on an island, desert island with no commitments, nothing to wake up for, what time would you probably drift towards going to bed and waking up? There's lots of other questions that we can ask in terms of when you think that you're at your peak alertness, but that's probably a good sort of rule of thumb. Evening types tend to like to go to bed, you know, midnight one or two. Morning types like to probably go to bed at nine. That's me.

And then wake up at, let's say, sort of five o'clock or six o'clock in the morning. Yeah, that's what we do. And that is, as I said... And it's so fortunate actually that we both like doing the same things. It must be a nightmare. It's a real problem with couples. You know, a lot of people I've seen recently have been telling me, you know, on dating sites, they would actually say, look, I'm a morning person. And if you're an evening type, then we're just not going to get along. So don't message me. But to come back to the point,

I think when is the optimal time to exercise? If you're a morning type, probably about two hours after you've woken up, two or three hours. Why wait that long? just simply know that if your goal is performance metrics and you want to maximize and sort of get your best times you're not going to do it within the first one to two hours because your body temperature has to rise and it will peak after about three or four hours and then it will drop down again what's fascinating by the way is that for that circadian rhythm of your core body temperature if you look at all o all Olympic world records and then you plot them as a function of time of day, you see that the vast majority of world records were always set at around midday or 1pm because that seems to be the optimal sweet spot when most people's body

temperature is at its highest and therefore statistically you're far more likely to perform at your maximum and therefore break a world record. Interesting. So if you have a normal nine to five or nine to six job where working out in the middle of the day is more difficult, I take it it's better if you're a morning person to sacrifice performance slightly and go to the gym before work. Where if you're a nighttime person, it's better to go after work would that be correct i think that is correct firstly no one should be sacrificing their sleep by the way to exercise yeah that was one of the big questions we got from listeners lots and lots of listeners asking that should i set my alarm an hour earlier to get in an hour's exercise or should i get the sleep you should get the sleep should we ideally just not set alarms and we should just go to bed at the time that we feel comfortable going to bed at and then just actually wake up? Yeah. I mean, so we've studied hunter-gatherer tribes whose way of life hasn't changed for

thousands of years and they just wake up naturally. And when you try to communicate to them this idea of artificially terminating sleep, they are so puzzled. Why would you stop something when it hasn't finished? And so one of the fears that people have when you say, well, don't use an alarm clock is, oh my goodness, I'm going to sleep in. And yes, you will for the first week or 10 days, because what you're doing is you're trying to sleep off the debt that you've accumulated across months, if not a lifespan. But gradually what will happen is that you will sort of sleep away that debt and then you'll gradually start to sort of come back and you'll find your nice sweet spot of awakening. And then it's like clockwork. It really is. As

long as you're not disrupting sleep with alcohol or caffeine or going to bed too late, you will just naturally start waking up at a very similar time. But I think your point coming back to exercise is a good one. Firstly, we shouldn't, you can't out-exercise your lack of sleep. You can't substitute one for the other. Exercise isn't like that. Exercise doesn't do the same biological, physiological functions that sleep does. They're complementary rather than sort of one being a substitute for the other. I would say just get to the gym whenever you can. It's going to feel better a little bit later in the morning or in the early afternoon than it is first thing in the morning. But if your opportunity window is simply at the end of the day to exercise, still do that.

Just know that you may not be at your peak performance. And if you get the chance at the end of the day to exercise, still do that. Just know that you may not be at your peak performance. And if you get the chance at the weekend, then go in the middle of the day. And then the last life factor I wanted to ask about was technology. You read at the moment about trying to switch off phones or even see people wearing blue light glasses and understanding how that impacts on our brains before we go to sleep. So I think the invasion of technology into the bedroom has been a real enemy of sleep. But I think ultimately, we have to work with technology. That genie is out the bottle, and it's not going back in anytime soon. But there are some things that you can really do. But again, let's speak

about the reasons rather than the rules. Why are phones and sort of iPads bad in the evening? Well, they did a great study where they took a group of people, had them read an iPad for one hour before bed versus just reading a book. The one hour of iPad reading before bed decreased a critical hormone called melatonin, which needs to rise to help time the healthy onset of your sleep. And that hour of iPad reading blocked melatonin by 50%. It removed 50% of all of that melatonin. Secondly, it delayed the peak of that melatonin by three hours. So if you read an iPad for one hour before bed in London, you're sort of much closer to Russian time than you are London, UK time. So that's the first problem with technology, that that blue light will actually harm your melatonin and the melatonin release. So how long before you go to bed should you really not be looking at a phone or an iPad or then a TV as well?

I typically like to fall asleep watching the news. Yeah, so televisions, the data in terms of what comes off those screens isn't really there yet. But for iPads and phones, try to stay away for at least an hour before bed. If you can't do that, if you can't resist that, then blue light blocking glasses can actually help. There are apps on your phone where you can actually just turn your phone to black and white, but that's not the only issue. If that was the only issue, then those things could work. The second problem with technology in the bedroom is something that we call sleep procrastination, which is a real thing, which is that you get into bed and you're perfectly tired. You could fall asleep right there and then, but then you think, oh,

let me grab my phone a second. I'll just check Facebook one last time and I need to send that tweet out. I'll just check email. I need to order those things from Amazon. And then you look up and it's 40 the night and check their phones. We know this is happening with teenagers. It is a real problem, that sleep fragmentation. Once you get into the habit, it's a very difficult habit to break. The principal reason seems to be FOMO, that there's just fear of missing out, that there's too much going online socially, that you don't want to miss out, so you'll check it. Did people respond back to me when I just, you know, I sent out a text message just before I slept? And if you can't resist that temptation, then the phone probably shouldn't be in your bedroom. The final thing is, let's say you're very good about your phone use that you put it into airplane mode throughout the night, but you still leave it next to your bed. Most people in this modern era, the first thing that they do when they wake up

is that they swipe right. And this tsunami of the world of sort of anxiety just comes invading into your mind. It is no way to wake up. That's not how we were designed to wake up. How long would you recommend waiting till you look at your phone after you wake up? Try the experiment where it's like breaking a habit. Start small. So begin by saying, I'm not going to check my phone until after I've brushed my teeth. Really simple. Just leave it alone, wake up, brush your teeth, and then check the phone. If you do that successfully, push the boat out a little bit further. Say, I'm not going to check my phone until after I've had my breakfast.

There is something so sublime in this modern era to just sit there and have breakfast with yourself, but with no technology and no phone. And when you try it, it's blissful. And at that point, then you can sort of swipe right and unlock it. And the reason that this is critical is because you've probably had this experience where you had to wake up for an early morning flight and it was really important. And you know that the night before your sleep is going to be shallow, it's going to be light, and you may even wake up two minutes before the 5am alarm. That's what we call anticipatory anxiety. You know something is coming, you have anxiety beforehand, and it prevents you from getting deep sleep. Well, having a phone next to you in the morning is like a diet version of that.

And so your brain is trained to anticipate that little jag of anxiety every morning. And so your sleep as a consequence is not going to be as restful and deep the night before. So it's not just that it's wonderful to wake up in the morning and not have to face that right from the off, but it's also going to protect your sleep the night before. So I want to go back a little bit. And we spoke earlier about how sleep deprivation impacts cardiovascular disease, cancer, our immune system. How does it impact on our mental health and our brains in that capacity? So it impacts mental health hugely. And in fact, in the past 20 years of studying sleep, we have not been able to find a single psychiatric

condition in which sleep is normal. And I think that by itself tells us everything that we need to know about the intimate relationship between sleep and mental health. What we found is that sleep, particularly dream sleep, essentially provides a form of emotional first aid, that it takes all of these stressful experiences that you've been having during the day, and it's almost like a nocturnal soothing balm, that it just shaves off the sharp emotional edges so that when you wake up the next day,

you feel better about those things, you don't feel as anxious or as, you feel better about those things. You don't feel as anxious or as depressed or as sad about those things. So sleep really is a form of overnight emotional therapy, as it were. And if you're not getting it, it can predispose you to having more anxiety. We're just about to publish a study that demonstrates this, that the less and less sleep that you have, the more anxious you then feel the following day. The more anxious you are, the worse you'll sleep the following night. It's a vicious cycle, self-fulfilling prophecy. So sleep is what can separate you between good sanity and mental ill health. You know, sleep is the best bridge between despair and hope.

That's a good night of sleep. Wow. So we had a lot of readers' questions, and I think we've answered almost all of them. But there were a couple I wanted to ask as we reach the end of this episode. Thoughts on sleeping pills and melatonin? So sleeping pills are different to melatonin. Sleeping pills are a class of drugs that we call the sedative hypnotics. And again, sedation isn't sleep. So the sleep that you have when you take sleeping pills is not natural sleep. If I were to sort of show you the electrical signature of your sleep,

your brainwaves, when you're on those sleeping pills versus when you're not, they are very different. Secondly, we know that sleeping pills have been associated with a significantly higher risk of death as well as cancer and so the advice at this stage is you should try to stay away from sleeping pills why because there is a safe alternative it's a psychological treatment called cognitive behavioral therapy for insomnia or cbti and if you want to learn more about this, just go onto the NHS, type in insomnia or type in CBT-I, and there's some great information there for you. You work with a therapist. It's just as efficacious as sleeping pills in the short term. But what's great is that when you stop working with a therapist, your sleep continues to remain wonderfully good for years later.

Whereas with sleeping pills, when you stop using them, not only do you go back to the bad sleep that you're having, you actually have something called rebound insomnia, which is where your sleep is even worse than when you started before taking those sleeping pills. So they really are to be avoided if you can. And how about taking melatonin? So melatonin seems to help under conditions of jet lag. That's where it can be very helpful. Melatonin, as we mentioned, is this hormone that it's called the hormone of darkness or the vampire hormone, not because it makes you look longingly at people's necklines and want to bite in. It's just because it comes out at night. And melatonin helps time the healthy onset of your sleep. And when you are mismatched in terms of your internal clock versus the external real world clock, which is what happens when we undergo jet lag and we travel through time zones, melatonin and taking it 45 minutes before bed, somewhere between 0.5 milligrams to 3 milligrams is optimal. That can help you with that jet lag. But once you're stable in a new time zone, melatonin in healthy young individuals doesn't seem to really help sleep. But what I would say is this, if you're taking

melatonin and you feel that it helps your sleep, then the placebo effect is the most reliable effect in all of pharmacology. So keep taking it. Okay, that's really interesting. And then what are your thoughts on sleep tracking devices and apps? Because there were a lot of questions about that. I sometimes wonder if they make it more stressful because you almost know you're being watched. There is that. And there's a new condition called orthosomnia,

which is where people essentially get too anxious about perfecting their sleep. And these sleep trackers give them information that may suggest they're not getting the sleep that they want and they become stressed and it becomes worse for them. It becomes harder for them. But for the majority of people, I actually think they're a good thing. What we typically say in medicine is what gets measured gets managed. And so having an awareness of what's going on in your sleep and how much you're getting and seeing patterns and trends, I think that's a good thing. You should note, however, that most sleep trackers are not accurate at separating out light non-REM sleep from deep

non-REM sleep from rapid eye movement sleep, REM sleep. They're probably pretty good at tracking your overall sleep time, but in terms of separating all of those different stages of sleep, as I could do at my sleep center, they're just not as accurate. They're probably about 60 to 70% accurate right now. Will they get there in, you know, two to five years time? I think they will. But right now we're just not quite there yet. So I would say track it, use it for what it is. Understand that some of those detailed sleep stages are not really accurate and you don't have to worry about them too much but making it a tool that helps you regularize your sleep and prioritize your sleep i think that's wonderful amazing

so matthew we like to close each episode with five take-homes for our listeners so five kind of key points from the discussion that if people were going to remember anything, this is what they're going to remember. And we would love to hear yours. So yeah, maybe I could give five tips for better sleep tonight. The first we've spoken about, which is regularity. As I mentioned, go to bed at the same time and wake up at the same time.

The second is darkness. You know, we are a dark deprived society in this modern era. And so not just avoiding the sort of screens and the computer screens and iPads an hour before bed, but try dimming down the lights in your home. Try switching off half of the lights in your house in the last hour before bed. You will be surprised at how sleepy you get when light becomes dim in the evening. The third tip is keep it cool. As we mentioned, you need to drop your core body temperature by about 1 degree Celsius to fall asleep and stay asleep. So a bedroom temperature of around 18 to 18.5 degrees is optimal for the sleep of most people.

That will sound cold, but cold it must be for you to fall asleep and stay asleep. If you get cold feet, it's fine to have a hot water bottle or put some socks on, but keep the bedroom cold. The fourth thing is walk it out. And what I mean by that is, if you are trying to fall asleep and you haven't fallen asleep after about 15 or 20 minutes, or you've woken up and you haven't got back to sleep within that same amount of time, do not stay in bed awake. Because what happens is that your brain

quickly learns the association that this thing called your bed is the place of being awake and not sleep. And you need to break that association. So the advice would be, get up, go to a different room, in dim light, just read a book or do some meditation and only when you are sleepy should you return to bed and there's no time limit and that way your brain will relearn the association that your bed is this place of consistently being

asleep and falling asleep so i think there the analogy would be you would never sit at the dinner table waiting to get hungry. So why would you lie in bed waiting to get sleepy? And the answer is you shouldn't do that. The final tip is we've already spoken about before, which is alcohol and caffeine. Try to be mindful of those things. You know, life is to be lived to a degree, and I don't mean to sound puritanical, but I also don't mean to be disingenuous regarding the science. My role is not to tell you how to live your life.

I just simply want to empower you with the knowledge and the science of sleep. And then armed with that knowledge, you can make an informed choice about what you would want to do with your life and your sleep. Matthew, this has been absolutely fascinating. And we feel, you know, when we started the delicious yellow podcast

everything we do in delicious yellow is to help people live better to be useful and to try and make vegetables cool and in starting our podcast we just really really wanted it to be incredibly useful so that we could help people live better and this has been just fascinating and we cannot thank you enough for coming on and sharing all of this with us. You're so very welcome. Thank you. And the thanks is actually going to be given to you because, you know, I am on a mission to try and help people sleep better and be more aware of their sleep. And I can't do it alone. You know, I need fantastic partners, people like yourselves, who give sleep some kind of priority so that you can dispense that information.

So I am grateful. And from this point forward, I'm going to anoint the two of you can dispense that information. So I am grateful. And from this point forward, I'm going to anoint the two of you as sleep ambassadors. Absolutely. So thank you so much for everything that you've done. Of course. And if anyone does want to learn more, Why We Sleep is in every bookshop, every online store. It is an easy, easy book to find. And it is so worthwhile buying and having a read of because, you know, we have barely scratched the surface in this episode. I mean, it is such a rich topic. So if you are able to get a copy, then I massively recommend it.

And have a lovely day, everyone. We will be back again next Tuesday. Thanks, guys. Sleep well. You're a podcast listener, and this is a podcast ad heard only in Canada. Thank you. thousands of shows to reach your target audience with Libsyn ads. Email bob at libsyn.com to learn more. That's b-o-b at l-i-b-s-y-n dot com.