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Great to be here with everyone. And a really important conversation today, I think, because I don't know about you, Whitney, but there have been nights in the last couple of weeks where I just haven't slept that well. There's just a lot of stress, there's a lot of worry, there's a lot of uncertainty and so forth. And has that been true for you?

ABVGT-SMITH Absolutely. I feel like my sleep has been a little less than ideal lately, for sure. Probably for a lot of you out there, too, I'd imagine.

CAO HINTONS Yeah, no, indeed so. So we're very lucky to have with us today the perfect speaker for this. He's a professor of neuroscience and psychology at Berkeley in California and director of the Center for Human Sleep Science, author of a book 3 years ago, why we sleep, and last year gave a TED talk and it's been seen nearly 10 million times now. So it's a treat to invite here Matt Walker. Thanks, Whitney.

You'll be back, right? Whitney will be back with questions from you all in a bit. Hi there, Matt. How are you? MAGNUS O'BRIEN

I'm good, Chris. And how are you doing? And thank you so much for having me on.

CAOEUR-JOSEPH MACKAY Well, thank you. It's very good to have you here. I mean, I guess that's going to be the first question on top of people's minds is, you know, is there a case that sleep matters now more than ever?

I think, firstly, it's important for me to not necessarily feed into people's anxiety regarding sleep. I know, as you mentioned, that sleep is difficult for some people when anxiety is high and of course that's never more so at present. So what I would say is that if anything that we're talking about feels as though it's a trigger, feel free just to come back at a time that feels better in terms of that anxiety level. In terms of sleep and COVID-19, right now, we don't necessarily have any evidence to suggest that there is some kind of a link between those 2. But certainly, what we know is that there is a very intimate relationship between your sleep health and your immune health.

And I'll give you just a couple of examples. There was a study some years ago that demonstrated that individuals who reported getting less than 7 hours of sleep had almost a threefold increased likelihood of becoming infected by the rhinovirus, which is what we all think of as the common cold, relative to those who were getting 8 hours of sleep or more. There was another study in over 50, 000 women, And what they found was that individuals who were getting 5 hours of sleep or less had a

70%

increased risk for developing pneumonia, which is a respiratory lung infection, relative to those who are getting 8 hours of sleep or more. But I think perhaps 1 of the most striking results in this relationship between sleep and immune health was a study where they demonstrated if you're not getting sufficient sleep in the week before you get your flu shot, you produce less than 50 percent of the normal antibody response, therefore rendering that vaccination significantly less effective. So I think, particularly actually on that last point, at some point, we will develop a vaccine for COVID-19. And then the question becomes, is the same thing true? If you're not getting the sleep that you need in the week before you get your COVID shot, will that immunization become significantly less effective?

I actually think that's an important question that we will need to answer in the future. CAO HINTONSOKAYAMPONGA

Okay, so no specific evidence. How could there be? This is a fairly new threat to humanity. But given that, In a way, if someone gets infected, there follows this sort of epic battle between a virus and their immune system. It's obvious common sense to give your immune system every shot it can, every chance it can.

And in many other cases, Sleep is known to do that. So, I mean, it really matters now. It's up there.

CAO HINTONS I think certainly, from an immune health perspective, we know that sleep essentially sharpens every tool in that box. Sleep essentially restocks the weaponry in your immune arsenal, giving you the greatest chance to fight off infection. And I think, as of at least April 2020, we don't have that evidence yet. I know that there are a number of studies, however, that are looking at that. Even some of the sleep-tracking companies are trying to rally efforts around that and examine this right now.

So we will have the data, I'm sure.

CA Well, a little later in this interview, we're going to dig into how to sleep better. I know you've got a lot of interesting advice in that regard. But before we go there, let's spend a bit more time thinking about the different ways that sleep can be really helpful now, because paradoxically, we actually, many of us, have, in theory at any rate, more time to sleep than we've ever had. And so, boy, if we could put that to use. How else could it help us, just during our waking day and the things that we're having to focus on now?

Sleep seems to provide a benefit to almost every major organ system in the body and many of the operations of the mind. And perhaps I'll just give 2 examples within the mind. 1 of the things that we know sleep is essentially incredibly beneficial for is learning memory and even creativity. And when it comes to memory, sleep is important in perhaps at least 3 ways. Firstly, we know that you need sleep before learning to actually prepare your brain, a little bit like a dry sponge ready to initially absorb new memories and lay down those new memory traces.

But that's not enough. You not only need sleep before learning to imprint those memories into the brain, you also need sleep after learning to essentially cement those new memories into the neural architecture of the brain so that you don't forget. And certainly there's very good evidence for that. In fact, sleep almost performs a file transfer mechanism where it takes memories and shifts them from a sort of a short-term vulnerable reservoir to a more permanent long-term storage site within the brain. And that's what we used to think that sleep was beneficial for, taking individual memories and holding onto them, as it were, future-proofing that information.

But we've since discovered that sleep is actually much more intelligent than that. Sleep will actually take new memories and start to integrate and associate them with pre-existing stores of information. So it's almost a little bit like memory alchemy at night, so that you wake up the next day with a revised mind-wide web of associations. And that leads to remarkable states of creativity. There's lots of good examples for this.

Studies in the laboratory showing that sleep can inspire almost a threefold increase in creative insights. And it's probably the reason that, you know, you've never been told to stay awake on a problem, but instead, you're told to sleep on a problem. And I think that phrase seems to exist in almost every language that I've inquired about to date, which means that this creative benefit of sleep transcends cultural boundaries. It's common across the globe.

CAO): That is 1 of the most mind-boggling things to me, about how you can be worried or puzzled about something, and you wake up in the middle of the night, and suddenly, you know, possibilities pop into place. The answer is there. And the fact that you're --" In 1 way, it's kind of annoying, because it means your unconscious mind has been there somehow, with the benefit of sleep, I guess, pre-associating and doing things that you were supposed to do all by yourself, and it's not fair. But in other ways, it's super cool. And so you're saying that there's, like, the 3 times the creative output, I'm very curious as to how that's measured, but I mean, that's an amazing claim, if you have enough sleep.

CA2C3D4L4E4L Yeah, so there's a lovely study done by some German researchers a couple of years ago, and the way that they did this, they gave people a series of problems that had a hidden embedded rule into it, and they never told them about that rule. But through exposure, perhaps gradually you can divine that hidden insight that is sort of locked into that problem. And then they bring them back, and then they test them at some point later to see if the light bulb moment has gone on for those individuals, and they've defined that sort of creative solution, that hidden rule. And you can do that after being awake, or you can do that after being asleep. And that's how they can start to tease apart, is it just time that the brain needs for creativity?

Is it time awake? Or instead, is it time asleep? And it was time asleep that seemed to gift the brain this sort of creative genius ability. And I think something else you mentioned there that's interesting, too. It's not just creativity, but sleep can also, I think, change our emotional and mood state, sort of feeling better the next day.

And that's what we're now starting to learn is another function of sleep for the mind. That sleep provides almost a form of overnight therapy, that sleep will take those difficult, stressful situations or problems. And sleep almost acts like a nocturnal soothing balm, just sort of taking the sharp edges off our emotional experiences, so that we come back the next day and we don't feel as challenged or as triggered by those events anymore. So it's not necessarily, I think, time that heals all wounds. It's time with a night of sleep that provides that form of emotional convalescence.

And that's perhaps particularly important in this modern era. I think there's a lovely quote by the American entrepreneur Joseph E. Kosman, and he said, the best bridge between despair and hope is a good night of sleep. And I think that's particularly prescient right now.

CA You can certainly imagine that a lot of people right now are wrestling with various mental health issues that are possibly exacerbated by the state that we're in. And I guess what I'm hearing you saying is, don't forget the simplest therapy of all, which is to sleep enough that that in itself may help. CAO Hunt,

Ph.D., Psychologist, University of Oxford Sleep, I think, we're learning, performs a form of emotional first aid, as it were. And it reminds me actually of another lovely phrase by Charlotte Bronte, who said that a ruffled mind makes for a restless pillow. And I think we've all had that experience of feeling sort of triggered that day and we just know that sleep isn't necessarily going to come at night. It's probably also the reason... Sorry, yes, go on.

No, you go on.

Yeah, I was just going to say, I think it's part of the reason that we're finding that sleep is so tied into psychiatric disorders and mental health conditions. In the past 20 years, for example, we've not been able to discover a single psychiatric condition in which sleep is normal. So I think sleep has a very powerful story to tell in our understanding and probably treatment of serious mental illness. CA

There's another issue that I suspect a lot of people are wrestling with right now, is that a lot of people's response to being isolated and feeling a bit stressed is to imagine more and more delicious things to eat and cook as we go to comfort food. And so some people, if they may wrestle with weight issues even more now than normal. I think you've argued that sleep has a role to play in the battle against gaining weight.

CA It does. And I think, very understandably right now, that may also be relevant. We know how this mechanism plays out, where if we're not sleeping well, we can start to gain weight. The first piece of evidence concerns hormones, and 2 specific hormones that control our hunger levels. Those 2 hormones are called leptin and ghrelin.

And I often say that they almost sound like hobbits, but I promise you they're not. They're actually sort of real hormones. Now, leptin, when it's released, is the signal to your brain to say you're full, you're satiated, you don't want to eat anymore. Whereas ghrelin does the opposite. It says you're not full, you're not satisfied with your food, you should eat more.

And when we start to under sleep, those 2 hormones go in opposite directions. We lose the signal that says you're full and you're satisfied with your meal, which is leptin, but we increase the hormone that says, no, you're actually hungry. Even though you've just eaten, you should eat more. And so as a consequence, people who are underslept can start to eat somewhere between 2 to 400 extra calories per day when you look at some of these studies. It's not, by the way, just that you start to eat more.

It's also that when you are underslept, your preference for different food groups actually shift. And so you start to desire more heavy-hitting carbohydrates and more simple, processed, sugary foods, rather than those more healthy macro ingredients, which also sort of sets you on a path towards a more, what we call, obesogenic profile. But it also actually changes how your brain operates in response to food. And we did a study a couple of years ago where we gave people a good night of sleep, or we kept them awake for a night, and then we placed them inside an MRI scanner, and we showed them different types of food groups, things that were very desirable, ice cream, chocolate, etc., or sort of healthy, leafy greens. And what we found is that when people were not getting the sleep that they needed, the sort of deep, hedonic centers of the brain were actually ramped up in response to desirable foods, and they started to want those more unhealthy foods.

And this in part was because the frontal lobe in their brain, which almost acts like this sort of CEO of the brain, regulating and controlling our impulses and our emotions, that was actually switched off by a lack of sleep. And so now you start to reach for those unhealthy food choices. But I think we can think of that more positively and say, perhaps sleep can actually be a tool in your box that can enable you to manage your weight more efficiently and correctly. And so getting that extra sleep should lead to, and that's what we see in the data, a healthier profile of body weight.

CA. Yeah, I suspect, speaking personally, there's no amount of sleep I could have that could make me lust after broccoli. But let's bring you into the sleep laboratory, and I'll order some broccoli and some oregano. Actually, char-grilled with a bit of olive oil and salt, it's not so bad. So someone listening to this, if you were trying to take a positive stance of this isolation time or whatever, thought, you know, I'm going to make this a time of learning and of creativity and so forth.

I mean, that's a possibility for someone. What you're saying is, don't forget if you're going to do that, don't forget to make sleep a key part of that program. That's going to help on every account. CAO HINTONSENSEN

That's right, and it is a time like no other where I think we have, in some ways, more sleep opportunity time. And in fact, there was a recent report out. And it's not a scientific report, so we have to be careful not to over-interpret it. And they looked at 68, 000 Americans and using sleep tracker data, sort of wearable tracker data. And they looked at the change in sleep since March 13th, which was when the president mandated a national state of emergency.

And what they demonstrated or suggested was that since then, there's actually been almost a 20% increase in sleep time on average as a nation here in the United States. Now, again, I think we have to be very careful. It could be that people are just sort of sitting in bed and you know working or watching television in the evening. But even if it's half that amount, I think what it may tell us is that this time, this very strange era that we're living in right now, has unmasked what is otherwise a chronic persistent debt in our sleep. And finally, you know, when you remove the brakes on sleep you can see that sleep flourishes in return.

Now I'm not suggesting that that's true of everyone. I think when we look at that data more closely, we'll probably see 2 clouds of data. 1 cloud of data where people are perhaps sleeping more, but then there will be this opposite cloud where people actually are sleeping significantly less because of the things that we've spoken about. Anxiety about the virus itself, concerns for example about whether they all hold their jobs, and people, of course, magically have lost their job. And so I think we'll see shifts, but that seems to be an interesting trend.

CAO):

It's interesting. I was having a conversation with friends last night about how surprising the final health statistics coming out of this whole thing may look. Because if people, A, have more sleep, B, are being isolated, so they're not catching all the other diseases they might be getting. I think flu stats are way down compared to a typical year at this point, partly because of the isolation. Less road deaths, less who knows what else.

I mean, just possibly there'll be some compensation for the horrifying death rates that we're going to see from COVID. But it's so interesting trying to put those pieces together. And here's what is also interesting to me. Like, 1 of the key symptoms of this virus is to make people incredibly tired, like a fever and incredibly tired. And it's striking to me that, in principle, we see those things as these awful things that happen, that those are the virus's weapons.

Actually, in a way, they're not right. There are bodies' weapons to try to beat the virus. We have a fever to try and burn it off. I think that's medically correct. That's the body's natural response with a lot of pathogens.

And with sleep, should we just view, like, if you're having symptoms and you're feeling really tired, does it help at all to say, this isn't the bug, this is me, and to listen to your body and to get all the sleep you damn well can?

CA I think it's a beautiful example, and it's another demonstration of that relationship that we spoke about. I think everyone knows that when you get sick or you get a common cold, what you really want to do is just curl up in bed and sort of sleep it off, as it were. And in fact, we understand that relationship that when you become infected there are a set of changes in immune factors that only go to work to try and fight these infections But they actually will signal to sleep that sleep in terms of its duration is needed in greater amounts. And in fact, there are immune factors that are sleep stimulating factors because the body knows that the best effort, sort of the most powerful healthcare system that it can call up in its weaponry defense against infection is this thing called sleep. And that's why we actually feel as though we want to sleep more.

It's not just because we're at home and we're not at work and we have the chance to sleep more, it's that your immune system is actually co-opting and bringing sleep into the equation to help fight that infection, because sleep is so powerful in that regard.

CA So given all these reasons why we need more sleep now than ever, perhaps. Talk to us about how to get it. What are your top tips on how someone can get a really great night's sleep? CAO HINGORANI

Yeah, I think beyond the typical, what we call, sleep hygiene factors, such as controlling your light in the evening, making your room a cool place, also being mindful of caffeine and alcohol. I could give 3 tips for what to do if you've had a bad night of sleep, and then if you're still struggling with sleep, 3 tips for perhaps how to better manage that. So firstly, if you're coming off a bad night of sleep, The first thing, and this may sound counterintuitive, particularly coming from someone like me, is not to sleep in the next day. Resist the urge to sleep in. Wake up at your normal time.

And there are 2 specific reasons for that. Firstly, your body has a 24-hour clock, and it expects regularity, and it thrives best on regularity. And if you start to change your wake-up time, you will confuse that 24-hour clock. So try not to confuse it. Wake up at the same time, even after a bad night of sleep.

The other reason is that if you sleep in late, you're probably not going to feel sleepy until later that following evening. So once again, you start to drift forward in time. The second piece of advice there relates to that. Don't necessarily go to bed any earlier than you would otherwise, because sometimes if you do that, even if you're feeling quite sleepy, you can then lie in bed and you can start to toss and turn. So try to push through until your standard bedtime that following evening.

The final piece of advice after a bad night of sleep is resist the urge to nap during the day. Now if you are a healthy good sleeper and you can nap regularly, then naps are just fine. But if you are struggling with sleep and have had a bad night of sleep, try not to nap, especially late in the afternoon. Because you can think of naps in that situation almost like snacking before a main meal. If you have a snack, you're not going to have the same appetite to try and sort of consume that main meal.

And the same is true if you start to snack with a nap just before your main sleep. So try to resist that. What to do if you are still struggling with sleep? I think the first thing is, if you're in bed and you've been awake for, let's say, 20 or 30 minutes, perhaps, the advice is take a break. Stop trying to fight sleep, because typically the harder that we try to force ourselves to sleep, the more stressed and anxious that we become, and the further that we push sleep away from us.

And, you know, it's a little bit like trying to remember a name where you're sort of the harder you think, the less likely it is that you are to recall that name. So try to step away from that. Again, I think the advice here 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 that you shouldn't. Just get out of bed, go and do something different in dim light, read a book, listen to a podcast, only return to bed when you're sleepy, and that way you'll relearn the association that your bed is the place of sleep.

I've got a final thing to say. Yeah, listen to a few TED Talks. I will put you to sleep. Yeah. Oh, sorry.

Go ahead.

Yeah, My voice, I think, and my inane words are usually the best sort of soporific known to women and men. I think the last 2 pieces of advice beyond, and that really is a powerful 1, is just please stop, give yourself a break and stop trying. That can be really helpful because otherwise if you're in bed, you're stressed and ruminated, you're teaching your brain that this thing called the bed is the place where you wake up. Instead, you retrain it to, when you return, understand that the bed is the place where you always sleep and you have confidence in sleeping. The last 2 pieces of advice have a wind down routine.

I think many of us have this idea that sleep perhaps should be like a light switch that we get into bed and we can just go from a 1 to a 0, that it's a binary, that we can just switch off and instantly fall asleep. Sleep typically is not like that. Sleep is much more like trying to land a plane, that you've got to gradually give it time to descend down onto that terra firma of good sleep. And the faster that you're going in terms of the mind, the longer that you need to give the mind to sort of gradually come back down into sleep. Do the 1 Meditation is useful.

Also taking a hot bath or a shower, having some kind of ritual. And that's useful, by the way, not just because a hot bath will relax you, but we also have this science in sleep called the warm bath effect, where as you come out of the bath, all of the blood has come to the surface of your skin, and when you get out, you radiate all of the heat out of your body, so your core body temperature actually drops, and that's actually good for sleep. It helps you fall asleep faster and stay asleep and more deeply. The last quick point I would make if you are struggling with sleep, and it's a simple tip but can be effective, remove all clock faces from the bedroom. It's fine to have an alarm clock, but try to take away any information about time.

Because if you're struggling with sleep, knowing that it's 2.15 a.m. Or 4 a.m., it's not going to help you. So remove those from the bedroom. The last thing I would note, by the way, is that if these things are not working well for you, and this is a tip from a wonderful sleep clinician called Michael Grandner, if I'm an athletic coach trying to give you tips for improvement, but you have a sprained ankle, then nothing I can tell you is going to be useful until you fix that, that sprained ankle. And what I mean here is that if these things aren't working for you, it could be that you have an underlying sleep disorder.

And if that's the case, These tips really aren't going to be effective until you go and connect with a doctor and see if you have an underlying sleep disorder that has been undiagnosed.

Whitney? So there are a lot of people chiming in with questions all over the world. And it's like there are a number of our viewers who are really appreciating what you're saying and are struggling with sleep themselves. And 1 of the questions we've seen is around stress as it relates to our sleep cycles and our dreams also. Just what impact can stress have on the kinds of dreams we have and our sleep cycles in general?

So stress within the body causes a number of different changes. 1 of the things that stress will do is elevate a hormone called cortisol, which is often thought of as not just an activating hormone but also a stress-related hormone. And typically, as we try to fall asleep, cortisol should actually be decreasing beautifully, and it should fall to almost its lowest point right around the time when we're trying to fall asleep. And so if we're stressed and if you in fact look at the disorder of insomnia, people start to decline in their cortisol like a healthy sleeper would do, but just around the bedroom period where you're starting to think about going to sleep, cortisol actually starts to spike back up again, and that can prevent people from falling asleep. It's what we call sleep onset insomnia.

So cortisol is 1 of the ingredients that can impact our sleep and our sleep cycles. The other factor is the nervous system in the body. And in fact, we have 2 branches of your automatic nervous system. We have the fight or flight branch, and then we have the more calming, what we call the rest or digest branch of the nervous system. And when we become stressed and anxious, we shift over more into that sort of fight or flight situation of the nervous system.

And we also know that that needs to dampen down in order to stay asleep. I think some people have had that experience where sort of mentally or even in your eyes you feel tired and you know that you're tired but there's just something about you know your heart rate and just the bodily stress despite the mind being tired that is preventing your body from falling asleep. How do we think about changing those? Well, as I mentioned, you know, the hot bath effect can help. Meditation, though, has also been proven to be very useful.

Meditation actually tries to shift you over into that more quiescent state of the nervous system. And in people with insomnia, mindfulness meditation techniques have proven useful. It reduces the time it takes them to actually fall asleep. So those are some of the ways that we can think about both how stress impacts our sleep and perhaps how we can try to combat it.

And to the point about dreams, do you find that stress also has an impact on the types of dreams that we have?

It does seem to have a relationship, and perhaps the best demonstration of this is an extreme form of that, which is a condition called PTSD, or post-traumatic stress disorder, where people have incredibly difficult traumatic experiences and stress. And what we commonly see there is a consequence of repetitive nightmares. In fact, it forms part of the diagnostic criteria for you to receive a diagnosis of PTSD. So there is certainly something about our emotional waking life that sort of bleeds over. It's almost a red thread narrative that transitions into our sleeping life and specifically our dreaming life.

We do know, however, a study published some years ago now demonstrating that if people are dreaming, and particularly dreaming about some of those difficult traumatic experiences, it can actually be beneficial, that it leads to clinical resolution of things such as depression and trauma and bereavement. So there is a relationship between our waking life and our dreaming life when it comes to emotional health. And we do think that sleep, and particularly dream sleep, plays a form of sort of mental health in that regard, and sort of dissipating and removing some of that emotional stress.

That definitely explains some of the unusual dreams I've been having, and I imagine it will be helpful for some of our viewers who have also been having odd dreams. So I'll be back later with other questions.

Sounds good. Talk a bit, Matt, about just the role of greens on sleep. And like so many people, the news is so interesting right now, your instinct is to take your phone or whatever to your bedside, you know, check out the news last thing at night, whatever. Is there evidence about this, about whether that's advisable or not?

CA So I think there is a feeling in the sleep science community, of course, that the invasion of technology into the bedroom hasn't necessarily been a good thing. Now, technology has done wonderful things for us. Is the enhancement and improvement of our sleep 1 of them? I think at this stage, it's probably not. I think in the future it actually will be.

But you mentioned the sort of the use of screens and phones in perhaps the hour before bed or even once we get into bed. I don't think that's advisable. Firstly, there is a concern about the blue light that comes from some of these devices. And that blue light will typically stamp the brakes on the release of a hormone that we call melatonin. And melatonin is a hormone that signals to your brain and your body that it's nighttime, that it's darkness, and we need that signal of darkness to enable the healthy timing of our sleep.

And in some ways, we are a dark, deprived society in this modern era. But if you look at the evidence, there is some evidence that those screens can actually change our sleep patterns. But more recently, I think that's being debated. What I do think, perhaps, is the greater impact of technology is less so the blue light coming from these devices, but more so the the the activation, the physiological activation that these devices trigger. And we know firstly that if you're using your phone it can cause something called sleep procrastination.

It's actually a thing where you get into bed, you are tired, you're sleepy, you could easily fall asleep, but you think well I'll just I'll just check Facebook 1 last time or I'll just send that quick tweet, and I'll just sort of go online and order a few of those things that I need. And then you look up and it's 30 minutes later and now you're deficient by half an hour in terms of your sleep. The other thing that these devices can do, though, is on the back end of sleep. If we bring those devices into the bedroom, a lot of us, I think the first thing that we do when we wake up in the morning is we swipe right, and then all of a sudden this sort of tsunami of anxiety comes flooding in. And that trains our brain to essentially expect that sort of stress every single morning.

It's what we call anticipatory anxiety. And I think A good example of this would be if you have to wake up for an early morning flight and you know that it's critical, let's say you have a job interview, there's just something about your sleep not as, it's not as responsive. And having your phone next to your bed is a sort of a diet version of that, a sort of a LIT version of that, but it's still present and it still affects sleep. So if you can, a good piece of advice is try not to check your phone for, let's say, just the first 5 minutes of the day. See if you can just sort of hold off and you can push that distance of anxiety a little bit further so you don't train your brain to think, OK, every night when I go to bed, the first thing I'm going to be doing is receiving anxiety in the morning.

CA

You mentioned melatonin. Some people swear by it as a natural sleep remedy. Do you recommend its use for some people or for anyone? IP Well,

Melatonin isn't actually a sleep-inducing chemical, at least so far looking at the data. It's a sleep-timing hormone, so it helps us regulate when the brain is told to go to sleep. So think of melatonin. If you were to consider, let's say, the 100 meter race at the Olympics, melatonin is the starting official that sort of begins the gun that starts the great sleep race. But that starting official with the sort of the starting pistol, they don't participate in the sleep race itself.

That's a different set of chemicals. So if you're transitioning between different time zones, that's certainly when melatonin can be useful to help sort of give your signal, sorry, give the brain the signal back of when it should be night and day. For most people though, melatonin isn't necessarily efficacious for improving their sleep. As we get older, the amount of melatonin that we start to release does actually decrease in total across the night, and that's where I think some of the evidence is actually interesting. It does seem to provide a benefit.

The 1 thing I would note is, at least here in America, 1 has to be a little bit careful because melatonin is not regulated by the FDA. And because it's over the counter, there was a study that looked at different brands and sort of vendors of melatonin. Is that relative to what it said on the bottle there was somewhere between 80% less or almost 460% more melatonin relative to what was suggested. So I think 1 needs to be a little bit careful for that. What would be the dose?

Well, it's usually a lot less than most people think. Some people will take 5 milligrams or 10 milligrams, thinking that more is better, which is a very natural thing to do with supplements. That's not really the case with melatonin. Studies have shown that really the effect, if there is 1, is best at something like 0.5 milligrams or even less than that. So that's the real problem.

CAOENNEY. OK. And Matt, Is that just for when you're changing time zones, or

do you think that's possibly effective for someone to take regularly? CAWTHONER-LONG, MD Well, I think if you are perhaps someone who is a night owl, so what we have are what we call chronotypes. So are you an evening type? Are you a morning type? Are you somewhere in between?

And in some ways, that's actually quite genetically determined. So you don't really get a choice so much as to whether you're a morning type or an evening type. Now, in evening types who like to go to bed late and wake up late, their melatonin rise doesn't normally start to begin until let's say 10, 11, even midnight. So for those individuals who are trying to drag themselves back if they have to go to work early in the morning and that they need to get to bed earlier than they would otherwise, 1 can try to see if melatonin is beneficial. But if you're young and you're healthy, melatonin doesn't necessarily seem to be very effective in terms of helping your sleep.

CA What about any other sort of, quote, natural sleep aids, from, I don't know, chamomile tea to alcohol? Any other suggestions?

IP So for chamomile tea, we don't have any good evidence. People have looked at this, and it doesn't seem to necessarily benefit. There may be some ingredients in chamomile that could have a benefit. But right now, no really good, strong evidence that at least I've seen. You mentioned alcohol, and I'm glad you did, because alcohol is perhaps the most used sleep aid, relative to at least prescription sleep aids.

And it's very natural that people have a nightcap, and they'll say, it really helps me fall asleep faster. Unfortunately, alcohol is the enemy of sleep. And Alcohol will hurt your sleep in at least 3 different ways. Firstly, alcohol is a class of drugs that we call the sedatives. And sedation is not sleep.

But when we have a drink in the evening, or a couple of drinks, we mistake the former for the latter. And alcohol will actually simply just numb the cortex, so you're just sedating yourself. And if I were to look at the electrical signature of your sleep when you've had a normal healthy night of sleep and compare it to when you've had alcohol, it's not the same. It's a different electrical profile. The other 2 dangers regarding alcohol and sleep is that firstly, even if you think you fall asleep faster, you typically will wake up many more times throughout the night.

What we call sleep fragmentation. So you wake up the next day and you don't feel as restored by your sleep because your duration of sleep, the quantity of sleep that you've had may be quite similar, but the quality of that sleep in terms of its continuity is actually significantly worse. The final thing about alcohol is that it's actually very good at blocking your dream sleep, what we call your rapid eye movement sleep. And we know that REM sleep is important for a number of different functions, including mental health and your emotional stability. So that's really why people, if they are struggling with sleep, they should really err away from trying to use alcohol.

It's not a sleep aid at all. It's actually going to harm your sleep.

CAO): And would you make the same comments about sleeping pills? Is that sedation not real sleep-inducing?

IP): It is. That is the case. The sleeping pills, typically, that are prescribed right now are a class of drugs that in fact we call the sedative hypnotics. Once again their action is they act on the same receptor in the brain that alcohol does. Now the way that they sort of stimulate and tickle that receptor as it were is a little bit different but in general that's what they're doing too.

They're trying to sort of downscale the activity in your cortex, sort of knock out your cortex, as it were. And once again, you look at the electrical profile, is not the same as normal, naturalistic sleep. CAOEUR-JACOBSON

That's the same. Sorry.

No, no, sorry, please go on.

CAOEUR-JACOBSON I was just going to say, you mentioned prescription drugs, and that's the same for over-the-counter sleep aids, that even if they do get you to sleep, they're just not --" I mean, is there any value to them at all, or should you just shun them, that they're just an illusion that they're giving you sleep? They're not actually giving you the true benefits of sleep? CAO HINTONSENGERAIN

Yeah, I think that that seems to be the case and it's the reason that back in

2015

or 16 the American College of Physicians made really quite a landmark recommendation. They suggested that based on the evidence looking at the magnitude of the benefit that these sleeping pills have relative to placebo and some of the concerns, the health and safety concerns regarding these sleeping pills, that they must no longer be the first-line treatment recommendation to people with insomnia. Instead, the suggestion was a treatment called Cognitive Behavioral Therapy for Insomnia, or CBTI. And it is this remarkable behavioral therapy and cognitive therapy that's been developed over the past 10 or 15 years. And it seems to be, if you put it sort of head to head with sleeping pills, almost like a Coke Pepsi challenge, it is just as effective as sleeping pills in the short term.

But what's beneficial is that when you start working with that therapist, and it can take somewhere between 6 to 8 weeks to course correct and retrain the brain to good sleep, it's very effective, you continue on with those benefits up to a year, recent studies up to 5 years. Whereas when you are taking sleeping pills and you stop, not only do you typically go back to the bad sleep that you were having, sometimes for some patients, you can have what's called rebound insomnia, which is where your sleep can be even worse. So right now, if people are struggling with sleep, they should really seek out this treatment called cognitive behavioral therapy for insomnia. That's the first-line recommended treatment that we have for sleep difficulties related to insomnia.

CAOENNEYSWORTHY, MD, MPH, WITNESS CONFERENCE WITNESS CONFERENCE I feel like there are still just occasional circumstances where those over-the-counter pills may be useful. I mean, when I'm hosting a TED conference, my mind, when I go to bed, is so buzzy. It's like there's no chance I will sleep at all for hours. And anecdotally, I found it essential for a couple of those nights to take an over-the-counter drug and at least get some sleep. You wake up, at least on the day, feeling refreshed, whereas when I haven't done that, I've woken up feeling like I just cannot cope.

Are there any circumstances where one-off use is appropriate? CAO

HINTONS Suddenly right now, people, in terms of prescription sleep medications, there is still a time and a place for those. But even there, it's really recommended for a short-term period, nothing more than a handful of weeks at best, and then we should look to alternative treatments. But certainly I do sort of sympathize and have empathy with that, you know, I've experienced that myself and particularly with things like jet lag I certainly will use melatonin to see if it can help. And you know if things like chamomile or melatonin do make you feel better then what I would say is that perhaps the placebo effect is 1 of the most reliable effects in all of pharmacology. So if you do feel as though it's working, then perhaps keep on with that, at least with the caveats that we've spoken about regarding non-regulated over-the-counter supplements.

No more than half a milligram, sounds like. Whitney? That's right.

There's some questions online about technology and the impact that can have on your sleep, specifically seeing a couple of questions about artificial light and how that might disrupt our sleep cycles, and then how we can use technology to benefit our sleep, like apps and that sort of thing.

Yeah, so we discussed a little bit about this sort of effect of blue light, and there was a study done at Harvard Medical School a couple of years ago, and what they found was that people who were using an iPad for 1 hour before bed, relative to someone who was just reading a book in standard light, firstly, the use of that iPad delayed the release of melatonin, that darkness-signaling hormone, by 2 to 3 hours. It also decreased the amount of melatonin by about 50% to 5-0. It also seemed to disrupt the amount of rapid eye movement sleep that those people were getting. And what was also interesting in that study is that when they stopped using the iPad before bed, there was almost a blast radius effect where their sleep was still disrupted for a couple of nights after. It took sort of a while to almost wash out the effects of that iPad use.

But as I said, there's been some more recent reports that seem to suggest that perhaps those devices in terms of the blue light may not necessarily be as powerful or impacting. I think it's more about the psychological, the cognitive activating impact that those devices have, and perhaps less so the amount of blue light. And by the way, I should note that it is particularly light in the blue part of the visible spectrum. So if you are going to have light in the evening, and the advice is, by the way, in the last hour before bed, not just about technology and screens, try to dim down half the lights in your house, and you'll be surprised at how sleepy that can make you feel. So I think that's 1 of, certainly, the pieces of advice.

It's not just technology in terms of light, it's also just the light that we have, the pollution that we have in the home itself.

CAOENNEY. I'll come back later with last questions from the audience.

Matt, how much sleep should people actually have? Is there a prescribed hour number?

So currently the recommendation is for people to get somewhere between 7 to 9 hours of sleep. And there certainly is a range. It's not necessarily a one-size-fits-all. It's very similar to perhaps the standard recommendations for calories. I could say that for the average adult, it's 2, 000 or

2, 500

calories a day. But depending on who you are, your physiology, what you've been doing that day, that will vary. But Right now, for the average adult, the suggestion is somewhere between 7 to 9 hours. I think the CDC suggests that there is a minimum of 7 hours in terms of a requirement. But again, it's going to be different for different people.

There will always be those edge cases, the tail ends of the bell curve distribution, as it were. But that's a good, I think, range to shoot for.

CAO): Do you think there are outliers, you know, the Margaret Thatchers and my wives of this world, who only need 5 hours' sleep?

IP): There are outliers. And in fact, there's been some recent work looking at what we call these short sleepers. And there are specific genes. There are a couple of genes, in fact, that have now been discovered that seem to be related to just innate short sleep as people who sleep somewhere between 5 to 6 hours a night. And that really does seem to be all they need.

You can sort of play around with the circumstances, you can bring them into the laboratory, you can take away technology, you can take away light, you can take away all cues that could otherwise influence their sleep and really sort of strip away everything but their natural sleep expression. And still, even when you give them, you know, a 10 or 12 hour period of time in bed as an extreme example, they still only sleep consistently, somewhere between 5 to 6 hours a night. So we definitely know that there is a very small, select proportion of the population that is a short sleeper. Of course, when I say that, many people say, well, I think I'm probably 1 of those, but statistically, the likelihood is perhaps quite low, if that's helpful.

CAO): Well, I'm certainly relieved a bit to hear at least that that's a possibility, because I'm married to someone who seems to never sleep anything like 7 or 8 hours and seems to be full of energy on many days. But

And I've been worried about

her ever since I heard your TED talk. Thank you. CA. Thank you. You're welcome.

CA. I've tried to encourage you to sleep. But this is actually a paradox, Matt, in that some of your findings are so powerful on the potential risks to us of not enough sleep. We haven't had time to talk about this yet, but you talk about risk of Alzheimer's, risk of many other things can go up, risk of heart disease and so forth. So that people could literally lie awake, worrying about what they just heard from Matt Walker.

And you yourself have sometimes done that, right? You've had these new discoveries and have woken up in the night and been worried about the fact that not only what you discovered, but, I am awake now, and this may be affecting me. Does that happen?

CAO): Yeah, it does. And firstly, I'm no sort of cardboard cutout of sleep perfection. I have struggled with bouts of insomnia during my life. And I'm probably the worst of all individuals knowing what I know. You know, I'm sitting there, as you mentioned, and I'm wide awake and I'm thinking, well, you know, my dorsal lateral prefrontal cortex is not shutting down.

I'm not releasing, you know, this specific sleep chemical. I know that, you know, Alzheimer's proteins in my brain may be building it. And at that point, I almost become like the Woody Allen neurotic of the sleep world, and I'm dead in the water for the next 2 hours in terms of sleep. So, You know, I joke about that, but I've definitely had my bouts and relationships with insomnia before. So I am very thoughtful about that and how you give a message of the importance of sleep, understanding that it could be triggering.

And I think, you know, some of the information that can be given in the talk or in the book could almost be taken as a sort of a sleep-or-else scenario. And that was never my intent. You know, I think when I was writing the book several years ago now, I think if you looked at the public, there was still this sense of sleep, you know, so what? The evidence was just so important that, you know, I felt as though we were at a stage where we thought of sleep as an inconvenience. And all I really wanted to do was try to perhaps change some of that belief to say, sleep is not an inconvenience.

Sleep is actually an investment. Sleep is an investment in your physical health as well as your mental health. And so that was really sort of the goal I was trying to offer. But I understand that it can be triggering. I think, you know, I struggle to wrestle with those tensions.

I feel as though it's important that people like the World Health Organization or the CDC not be gun-shy in terms of giving us the information regarding risks in terms of our physical and mental health. And so I do feel it's important that the science of sleep is given to the public, but I also understand that it can be complicated and triggering for some people.

CA So someone who hears this right now and wakes up tomorrow at 2.30 a.m., fretting about the fact that they're not getting enough sleep and what that may be doing to them. Give them some practical advice. What should you do if you wake up consumed with anxiety in the middle of the night?

CA So there again, I think it's really this case of, firstly, trying not to worry about it too much, being kind and giving yourself the break from sleep, not sitting there tossing or lying there and tossing and turning, just understand that tonight is not my night, Perhaps I can just step away from sleep. Let me get up. Let me not continue to reinforce to my brain that almost like a dentist's chair, when I go to a dentist's chair, I've typically learned that things don't usually go well there and because it's a reinforcing sort of self-fulfilling prophecy. Don't let the same thing happen to your bed. And the way that you can prevent that is, if you are struggling, if you are tossing and turning, the best advice is get out of bed, do something different, only return when you're sleepy, and that way, gradually, you'll feel better, you'll feel confident about your bedroom and the bed being this place of restful, confident sleep, rather than this trigger for rumination, anxiety and wakefulness.

CA1. Wonderful. Thank you. Whitney? WP.

There are so many questions out there, many of which we won't get to. But we should find a way to get some of these great questions in front of you, Matt, so that you can answer them. But I think the 1 that I'd just like to ask here is about physical exercise. We're seeing a lot of people just wondering how they can use exercise to help with their sleep.

So the relationship there, I think, is quite powerful. We know that physical activity during the day does seem to have an improvement effect on your sleep at night, particularly in terms of the quality of your sleep. There is some evidence that it can improve the quantity of your sleep. But physical performance and physical activity, or even just necessarily, it doesn't have to be that you need to go out for a 10-mile run. Even lower level physical activity beyond sort of 20 or 30 minutes seems to have a beneficial impact on subsequent sleep at night.

By the way, the relationship is also present in the opposite direction. When you start to sleep well, your motivation to actually go out and exercise the next day is increased. And also your ability to physically perform exercise is also improved at a number of different levels as well. So there is that relationship, and it's actually bidirectional.

CA AMDURO-CHAVEZ Wonderful. Last question for me as well. You started your TED Talk with a spectacular claim that lack of sleep had a big impact on sexual performance, certainly for men. Does it go the other way? Is good sex also great for good sleep?

So, there is a little bit of evidence to suggest that physical intimacy with your partner in that regard can actually enhance your sleep. Some of that I think is just related to the relaxation that comes after following that physical intimacy, that it ramps down the fight or flight branch of the nervous system and you go gradually into this more sort of relaxation state of the nervous system. Some of the hormones that are released seem to be beneficial, things such as oxytocin. And we also know just that people who are having physical intimacy with themselves, should we say, has been used as a technique for dealing with insomnia. So there is a little bit of evidence in that regard, and certainly I think if it's satisfying for all, that's when we typically see a good benefit.

CA Well, never let them tell you that TED conversations aren't practical. MT Yeah. CA Matt, it's been a delight to have you here. Thank you so much for this conversation. And we may have some other questions to put to you, to post on our blog or something like that from the many other people who had questions.

But really, thank you so much.

CA You're very welcome, and I'd be delighted to try and offer any ongoing help that I can and respond to more questions. And thank you again for hosting me both here and on the TED stage last year. Thank you.

Whitney, do we have anything to say about the rest of this week, which I guess would be tomorrow at this point?

That's right. We have 1 more day of interviews. Tomorrow's interview is with Elizabeth Gilbert, the acclaimed author, and she's going to give us some tips on how we can really work through feelings of being overwhelmed during this time, which I think is something that a lot of us experience at 1 point or another, perhaps in sort of an ongoing way, depending on what your circumstance might be. And so I think that'll be really a great help for us as we round out the week.

CA You know, the very first episode of the TED interview was with Liz Gilbert. And I just found it to be astonishing, like, really astonishing. As she said in that interview, I'm not her demographic. Most of her books are targeted at women, or seem to have been. But the way she describes the emotional landscape we all are facing.

I just found it so profound. And so I actually cannot wait for the conversation with Liz tomorrow. She's holed up by herself. I spoke with her a couple of days ago, but She's ready to come and share many thoughts on how to make use of this time, how to navigate it. I think you're really in for a treat and do share notice of that conversation.

Thank you, everyone, for listening. It means a lot to us that you come and spend this time with us, build community with us, learn with us. As we've said before, we'll say again, we're all in this together. Thank you, Matt and Whitney. Thank you all.

WBK-KLMN-BFM Take care, everyone.