Instant Genius - Dr Michael Mosley: Why is sleep so important?

Episode Date: July 27, 2020

If, like us, you love to read a good science book, (and thanks to this podcast we’ve read a fair few over the years), you’ll probably recognise the feeling of having more questions about its subject at the end of the book than before you even turned page one. It’s because of this that we decided to launch the Science Focus Book Club, where we pick out what we think is an excellent, thought provoking science book and ask your questions to its author. You can sign up for the newsletter to find out which book is coming up next, but to give you a taster, in May, our legion of science book fans read Fast Asleep, by Science Focus columnist and BBC presenter Dr Michael Mosley. In this week’s podcast we’ve selected a few of our favourite Q&As where he explains everything you need to know about sleep; from what it is, why we need it and how to get more of it. Let us know what you think of the episode with a review or a comment wherever you listen to your podcasts. Subscribe to the Science Focus Podcast on these services: Acast, iTunes, Stitcher, RSS, Overcast Read the full transcription [this will open in a new window] This podcast was supported by brilliant.org, helping people build quantitative skills in maths, science, and computer science with fun and challenging interactive explorations. Listen to more episodes of the Science Focus Podcast: Dr Guy Leschziner: What is your brain doing while you sleep? Alice Gregory: How to get a good night's sleep Brian Sharpless: Exploding Head Syndrome Dean Burnett: The neuroscience of happiness John Lennox: Is religion compatible with science? Emma WhispersRed: Why ASMR gives you tingles Hosted on Acast. See acast.com/privacy for more information. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Visit name, Go.com to learn more. Well, sleep is critical for your mental and your physical health, and there are different stages of sleep, so there is deep sleep, which happens in the early hours of the night or the morning, and then there's REM sleep, rapid eye movement sleep. During deep sleep, we know that you release all sorts of things like gross hormone, it's an important stage of repair. It is also really important for your immune system, because all sorts of components of your immune system, such as cytokines and antibodies, are created doing deep sleep. And we know if you

don't get enough deep sleep, then you are much more vulnerable to viral infections, which makes this particularly important. You're listening to the Science Focus podcast from the BBC Science Focus magazine team, with the UK's best-selling science and technology monthly, available in print and in several digital formats throughout the world. Find out more at sciencefocus.com or look out for us in your app store. Hello, I'm Alexander McNamara. editor at BBC Science Focus. Now, if like me you'd love to read a good science book, thanks to this podcast, I've read a fair few over the ears, you'll probably recognise the feeling of having more questions about its subject at the end of the book than before you even turned page one. It's because

of this that we've decided to launch the Science Focus Book Club, where we pick out what we think is an excellent, thought-provoking science book and ask your questions to its author. You can sign up for the newsletter and see who's coming up next at sciencefocus.com forward slash science book club. But to give you a taster, in May, our legion of science book fans read fast asleep by Science Focus columnist and BBC presenter Dr Michael Mosley. In this week's podcast, we've selected a few of our favourite Q&As where he explains everything you need to know about sleep, from what it is, why we need it and how to get more of it.

He speaks to our editorial assistant, Amy Barrett. First, you've written in your book about going to bed and we shouldn't sort of stay in bed if we're struggling to sleep. What should we do if we're lying at bed, staring at the ceiling, wishing if you get to sleep, but not being able to. Yes, that's one of the problems about reading books about sleep as you start worrying about how much sleep you're getting and that keeps you awake.

So the advice from the psychologists is that what you absolutely need to do is associate sleep, sorry, bed with sleep and sex and nothing else. And the problem is that once you get into a bad pattern where you're looking at your smartphone or you're watching tele or you are simply aware, wake worrying, then you've broken that link between sleep and bed and you have to reassert it. So the advice is, broadly speaking, that if you wake up in the middle of the night, 3am, which is the classic form of insomnia, then after about 10 or 15 minutes, and you feel you're not going to drift off, then you should get out of bed.

You find a sort of nice warm space, which you've set up earlier with some really boring books or perhaps some music with the sort of rhythm of about 60 or 70 beats a minute. Jazz seems to be particularly good. And you kind of just sit there and you chill out until you feel relaxed and you feel sleepy and then you go back to bed. This seems to be a very effective way and just lying there worrying about it and worrying about how bad you're going to feel the next morning is one of the worst things you can do. It's hard to keep those boundaries, especially now, isn't it? I know it's in a flat where there's only sort of a few. rooms, one of them being the bedroom. It's hard to kind of keep that as separate just for sleeping.

It is. It's very hard indeed. I'm fortunate at the moment that I have a house where I can find the space. I sometimes, when I'm traveling and if I'm traveling with my wife and we're in a hotel room, I'll go into the bathroom and just kind of lie down on the floor in the bathroom with a pillow. Not comfortable, I have to say, but that's one. That's one. one way of coping, but I do appreciate it is tricky, but it does seem to be very effective. There is another approach to it, which some people try. I personally find it quite challenging, which is called acceptance theory. And I write a bit about that. And that's where you kind of just learn to accept the fact you're awake. You challenge the thoughts you're having. So if you're

thinking, oh, go off, I'm awake again, I'm going to feel terrible tomorrow. And those sort of thought you go, it's fine. I generally find I go back to sleep again. And there is also sort of breathing exercises you can practice. One of them that I like is called 4-2-4. And what you do there is you breathe in through your nose to count of four. Hold it for two and then out again for your mouth to count a four. In, hold it and then out. And you just do that for a minute or two. and what you'll find is your heart rate will drop and the drop in the heart rate is one that triggers for sleep. It's very kind of calming.

It's best to practice it during the day as well any time you feel stressed. But these sort of breathing exercises are unbelievably effective and they just kind of distract you as well. And another approach is to do something like mindfulness meditation and I try to do that during the day. And again, some people find that's brilliant at night time. they just kind of start listening to their breath and they, but it's tricky if you haven't already got into the habit

because taking up something in the middle of the night is never a good idea. A new skill ought to be something that you've already kind of incorporated into your life. But mindfulness is very effective as well. Okay, Michael. Tell me about your new book capacity. Sure. So the book is about sleep. It's about how we know what we know now.

the stages of sleep and then critically it's about how you actually improve the quality of your sleep. And there have been quite good books out there ready looking at the science of sleep, but very few which have addressed a question of how you can actually improve your sleep. And unfortunately, a lot of the standard advice is pretty ineffective, I have to say. It's either unbelievably obvious or it doesn't work. And that's really why I wanted to write the book, because I have been an insomnia up for some time, and I've managed to, broadly speaking, sorted out. So I kind of wanted to share what I knew with other people.

Why do we need sleep? Why is it so important? Well, sleep is critical for your mental and your physical health. And there are different stages of sleep. So there is deep sleep, which happens in the early hours of the night or the morning. And then there's REM sleep, rapid eye movement sleep. During deep sleep, we know that you release all sorts of things like gross hormone. It's an important stage of repair.

It is also really important for your immune system because all sorts of components of your immune system, such as cytokines and antibodies, are created during deep sleep. And we know if you don't get enough deep sleep, then you are much more vulnerable to viral infections, which makes this particularly important now. And in deep sleep, you also are channels in your brain which open up and live. literally wash out the brain. This is a system called the glymphatic system, which was only recently discovered. And if you don't get enough deep sleep, that puts you at greater risk of things like dementia. Plus, doing deep sleep, a lot of memories are consolidated. They're moved from sort of

short term into the long term. So that's critical. And rapid eye movement sleep, REM sleep, where you lie there and your eyes flicker crazily, that is actually linked with very much. Vivian dreams, and it seems to be particularly important for your psychological health, that it's while you're having these intense dreams, that you're processing a lot of the emotional things that go on during the day. And so if you don't get enough REM sleep, you tend to feel irritable and out of sorts. So REM sleep is also very important for shifting memories around. So those are the two main components, but there are lots of other things, obesity, diabetes.

I could go on for a long time about the list of things and the reason that. why you might want to make sure you're getting a decent night's sleep. So how long should we be sleeping for? Hugely variable, depending very much on your age. So as a baby, you'll be sleeping 14 hours a day. When you're a teenager, you probably need at least nine hours, eight to nine hours. You often don't get it. And when you're an adult, it's probably somewhere in the region of seven hours.

And there's a sort of myth that as you get older, you need less sleep. In fact, you need just as much. You just don't get it. And so that's kind of one of the things I write about as well. And there are some people who can get by on very short periods of sleep. They call them sleep mutant. There is a family they found recently, which have a particular genetic profile. And they get buying quite comfortably on four to five hours, but most people can't.

It's very much a sort of bell-shaped curve. And the evidence is pretty strong that, broadly speaking, we need around seven hours. but again, one of the things I address in the book is a concept known as sleep efficiency because people tend to think, I get to bed 11, I get up at 7, that's 8 hours sleep. In fact, you're probably awake for about an hour of that time, so you're only actually getting 6 hours. And the evidence is pretty strong that the benefits come from having a good sleep efficiency, which means somewhere around 80 to 85% of the time in bed you should be asleep. and not just kind of lying there worrying about sleep or other things or your life or whatever is keeping you awake.

I mean, I for one, know that I've been spending a lot more time in my bedroom now because of the lockdown than I ever was before. Is that going to be causing me some sleep problems then? Have you been having sleep problems? I mean, I think everybody I've spoken to you is having sleep problems. It's just a difficult time to know what causes, though, I suppose. Absolutely. And it's obviously about stress and things like that. but it is also about the breakdown of routine and, as you said, spending a lot more time in your bedroom. Now, you can try and allocate bits of your bedroom to different tasks.

So you have the bedroom where perhaps you work or you do whatever you do. And then the bed, the right side of the bed, left side of bed, whatever you do, the bit where you sleep. So you do not take your laptop to bed with you. You do not take your phone to bed with you. The only thing is maybe a boring book which you read. and that's kind of it. So one part of the bedroom is work, play, other stuff, and the other side is, this is where I sleep.

It's really about establishing habits. That is hugely important. And beyond that, another component, which is not widely recognized, is the importance of the impact of food on sleep. And I write quite a bit about that because there's been a lot of research which has recently emerged on the way

eating a mid-Tranian-style diet, the benefits that has in terms of inducing more deeply that what you eat really does have a big impact. And it's partly because of its effect on mood, but also because of its effect on the microbiome, on the microbes that live in your gut. And they, in turn, if you feed them right, seem to produce sort of sleep-inducing chemicals. So it's about what you eat. It's about routine. and it's about a number of other things as well.

So what should we be eating then to help us sleep better, especially during this time? A lot of fibre. Fiber seems to be particularly good for your microbiome. I bang on about the Mediterranean diet because it has so many benefits. There's a lot of research now showing that medtrainian diet, one of the ways it seems to be beneficial

is because it also feeds your microbiome. It's rich in fibre. So the Mediterranean diet I'm talking about, is one which is oily fish, nuts, legumes, plenty of veg and things like that, and a glass of red wine in the evening, but preferably not much more than that. And olive oil seems to be a key component as well. And if you have all these things, then that seems to be a broadly anti-inflammatory diet. And that means there's many evidence that depression,

anxiety are at least in part induced by inflammation in the brain. And so an anti-inflammatory diet seems to be good at reducing your risk of all sorts of things, heart disease, cancer, diabetes, but also sleeplessness. And that seems to be really important. So if you can kind of shift into that sort of diet, more nuts and more olive oil, more legumes, then that seems to be a really good way to go in terms of sleep, but also all the other things. Because one of the other critical things for on good night's sleep is to ensure that you are relatively slim. Because unfortunately, obesity is linked with lots of fat around the neck and around the gut.

And that leads to snoring. It leads to sleep apnea. And again, mid-trainian diet, particularly a kind of calorie-controlled one, seems to be a good way of reducing central obesity. And that's one of the other things I bang on a lot in this book and other book. because I do think it's a very important message. Jason's picked up on your routine of getting up every single day at 7am. He says, does a weekend lion help? Can he keep his weekend lions?

Unfortunately, weekend lions, although lovely, are probably not terribly good. It's almost like jet lag, because if you get up a couple of hours later, say three hours later, then that would be the equivalent, say, of travelling to Athens for the weekend. and your body really doesn't like jet lag. So it feels quite good at the time, but unfortunately when you come to Sunday evening, if you've been getting up on Saturday and Sunday morning at 10 a.m. rather than 7 a.m.,

then it means you're going to struggle to sleep that night. It's probably fine when you're young, you're much more adaptable, but unfortunately when people get older, that's when they need routine more than ever. So I'm afraid the lion is, for most of us, is not a great idea. David Hawkins has noticed that during the lockdown, most of us are having sleep issues. Can you just explain why that is?

Sorry, during the lockdown, he's... Most of us have had sleep issues. Sure. I think it's in part because we've broken with our routine. A lot of people are not going into work. And that means they're sort of lying in. They're possibly watching box sets late at night. and eating junk food.

And we know the impact of diet of what you eat on your gut, on your microbiome, on your weight, on your waist, and on your sleep is very profound. So I think it's largely a product of that, the fact that routines have been broken. And also that people are obviously much more anxious. And there's a study out from the Institute of Fiscal Studies today showing that rates of anxiety have shot up. during lockdown and that's not surprising. But it just means you're going to have to kind of prioritise routine, be very mindful of what you're eating. And this might be a good moment also to take up mindfulness. There are lots of apps out there, but that would be one way of

coping with stress because these are undoubtedly difficult times. But when you're sleepless, that unfortunately adds to all the other stuff. Lack of sleep, poor quality. sleep means you're going to feel less like exercise, more like eating junk food, and you're going to start snoring a lot. Because when you pile on the weight around your neck, that's when you start to really, really snore. So this is a moment to try and take your health into your hands. And yeah, good luck. It's difficult. It is a vicious cycle sometimes, isn't it? I mean, both Ali and Emily have commented about dreams making them more tired. But the more tired you are, the more stress you are, so perhaps that's good sleep you're getting.

Yes. And it's interesting that there have been a number of websites recently, which are dedicated, in fact, asking people to kind of describe their dreams. And some of the dreams are helpful, some are not. I came across one the other day where somebody was dreaming about a sort of a rising snake, which this rabbit then lept on and devad, and he interpreted that as being COVID-19. being eaten by a white rabbit. I'm not sure the meaning.

But I think the thing about dreams is we are certainly reporting more vivid ones, but that is at least in part because people are lying in more. Because when you're being woken, you know, abruptly by the alarm clock, you're less likely to recall your dreams. So the fact that you're recalling your dreams is probably as much a product to the fact that you're having a lie in as anything else.

I don't think the dreams themselves are likely to be making you feel and more tired. As I said, it's just a byproduct of the fact that your life is now disrupted. And is it, you were talking about deep sleep and REM sleep? Is it that we dream in REM sleep only? No, you dream in both REM sleep and in deep sleep, but in REM sleep it seems to be particularly intense. And REM sleep is weird. If you've never seen anybody, then kind of Google it or watch your partner do it or your child do it. It's very, very strange. You see these eyes sort of flickering to and fro. And the thing we know about REM sleep is that during it you are totally paralyzed,

apart from your eyes and you're breathing. And that seems to be because during REM sleep, you have these intense dreams. And if you weren't paralyzed, you'd be crashing around the place and jumping out of bed and sort of hitting your partner and things like that. So it seems to be a really important part of sleep, certainly for humans. And as I said, you do sleep as well. have dreams doing deep sleep, but not as intense. And the intensity seems to be a big part of the way in which you kind of process the emotions of the day. As we know during REM sleep, you also don't

produce anything like the same levels of adrenaline. I mean, my personal dream I have over and again is the one where I'm kind of running to catch a crane. It's a sort of frustration dream as much as anything else. I'm either being chased or I'm chasing something and I'm never quite catching it. One I had last night with a suitcase. I'm packing it to go on holiday, but every time I put something in it falls out and then I just, and I know the train's going to

go and it's fairly obviously an interpretation of it's frustrationly, it's kind of filling hemmed in. I want to go on holiday. So whether that is actually helping me process or not, I don't know, but there are like

seven classic dreams you can have and that is one of the most common ones. feeling of either chased or being chased. Katasina has asked, what's the best percentage of REM and deep sleep during the night for our health? Broadly speaking, the amount of REM sleep you get is on average something like 17 to 20%. The only way of really telling is to have a sleep activity monitor. And I recently got hold of one because they've got a lot better. If you're going to get one, get one that also measures your heart rate

because one of the things that happens when you're falling asleep is your heart rate goes right down. That's kind of the thing that puts you to sleep. It's also a reason why you really don't want to be doing exercise very close to bed because your heart rate's up. So one of the triggers for sleep is the heart rate. Dropping breathing exercise, reduce your heart rate. That's another reason why they help you fall asleep.

But the other thing about your heart rate and stuff like that is with the activity monitors is doing REM sleep, your heart rate shoots up. So although you are paralyzed, although you appear to be in deep sleep, your heart rate is actually racing. And these are things that the activity monitor measure. So based on that, and there are a number of them I use a Fitbit. Broadly speaking, REM sleep occupies something like 17% of the sleep. and deep sleep anywhere between 8 and 20%. And the rest of it is kind of light sleep. And it's kind of interesting looking at the stats.

So as you get older, the amount of deep sleep you have kind of drops off. It's broadly around an hour when you're in your teens and then it falls to much less than that as you get older. And deep sleep, as it seems to be particularly refreshing, particularly for the older brain. and changing what you eat, the fibre seems to be a good way of inducing deep sleep. There have been a number of smallest studies which have shown broadly that eating sort of sugary carbly stuff is very bad to deep sleep, whereas eating sort of fibre rich foods is good for deep sleep.

So it's the likes of legumes and stuff like that you should be eating certainly at nighttime rather than perhaps the milky drink. Don't eat cheese before bed either. There are a number of myths, and I have to say cheese, the idea that cheese gives you nightmares seems to be one of them. They actually did a study at the University of Surrey some years ago, in which they got 200 people to keep a record of their dreams, and then they had to eat cheese every night for a month.

And they found there was no correlation whatsoever between the amount of cheese they're eating when they ate it and their dreams. But no, I don't think cheese eaten just before you go to bed is a great idea, mainly because your body is switched off the night. Your gut wants to go to bed. It's kind of like a busy restaurant. You come in and you shove food down,

and then your digestive system has to crank up. That will raise your blood pressure. It will raise your heart rate kind of just at the time when you want to go to sleep. So certainly a heavy meal eaten late at night is a really bad idea. A small nibble of cheese, I suspect, isn't going to make. a lot of difference one way or the other, and particularly nice smelly cheese, but then you're going to be shoving a few probiotics down there as well. And how can you tell if you're getting good quality sleep?

I think the most reliable indicator of whether you're getting good quality sleep is do you feel terrible when you wake up or not. There isn't actually a formal test you can do, which is what you do is you go to bed in the afternoon. with a quiet sign at the door. And you set your alarm for 15 minutes, and then you close your eyes. And the question is, do you fall asleep before the alarm goes off? If you do, then this suggests you are sleep deprived.

Because falling asleep quickly is not actually a terribly good sign. It's a sign that you're actually very sleepy. And if you fall asleep within 10 minutes, that means you are seriously sleep deprived. 15 minutes, you have a problem within 20 minutes. minutes is fine. There's actually a version of this test, which was originally developed by sleep researchers at the University of Pittsburgh, which is quite entertaining where you get a metal spoon. Again, you kind of look at your watch. You put a metal tray by the bed. You hang your hand

over the side of the bed and close your eyes. The idea is when you fall asleep, the spoon falls out of your hand. It hits a metal tray. It goes clang! And you wake up and you look at your watch and see how long it's taken. I think that's, I've done it, it's quite entertaining, but I think just setting your alarm is probably simpler. And obviously, if you're falling asleep during the day, if you're falling asleep sitting on the sofa, if you're falling asleep in the cinema, well, we don't go to cinema anymore, obviously, but falling asleep during the day is an indication that you are sleep deprived. Alice has noticed that there are some dreams that are common to all of us, you know, ones you're saying about running for a train, flying, your teeth falling out.

Why is that? Why does some people have similar dreams? Not sure. There are all seven archetypal dreams, which everyone has in variance, and they are the ones you've described. One of the most common is the one that I described, which is the one where you're racing to cat something or, you know, the frustration dream. Another is falling. I've had quite a few of those. You're clinging to the cliff edge and then you fall. Being naked in a public place, that's a common one. Having your teeth fall out, which is probably said to be linked to fear of aging. And they're all variants on anxiety dreams. Why we have these particular seven, I'm not entirely sure.

I imagine it's probably a cultural thing. I don't know whether people in other parts of the world have the same one. Again, another common one is going into an exam and being completely unprepared. You haven't read, you haven't revised, you haven't done anything. I don't know if that is a very common one, but whether it is a culturally specific one or not, I don't know. And then beyond that, there are lots and lots of crazy dreams. And obviously Freud and Jung made a big thing about, well, Jung in particular, about archetypal dreams. But statistically speaking, the seven I've described are the commonest, and they're all variants on anxiety dreams.

Natasha has asked about teenagers whose sleep patternships seem to be more nocturnal. Should they be encouraged out of that? Okay, so it's a reality. The truth is that when you're a teenager, you time shift. So most of us, there's larks and owls. So I am a lark. I like to get up early and I like to go to bed late. I'm sorry, early as well, about 11 o'clock. Hours typically, they tend to go to bed late and get up late. And you are, as a teenager, you shift by about two hours. And there is a biological explanation for this, which is that. Mother Nature, if you like, wants you to separate from the rest of the clan. You're having to learn to be independent as a teenager. And one way you learn to do that is by hanging around with your peers. And one way you do that is by staying up late at night. So you're with them, you're a gang, you learn skills, you do things like that.

Plus, it is hugely useful for the tribe that some people are awake late at night in case there are predators around. So all of these are actually powerful biological reasons why teenagers time shift. So I'm a big fan of trying to shift the time at which teenagers have to go to school later because I think it would fit in with their chronobiology better. And there have been studies particularly in the States, which have shown a remarkable impact of starting the school day just 40 minutes later.

But having said that, I would try to encourage your teenagers to at least get up by 9 or 10. you know, not necessarily 7am, have some sympathy, but it would be reasonable for them to have a pattern and for that pattern to include 9am. Emily has said that her dad always falls asleep to Radio 4. But does the continued noise once you've fallen asleep actually affect the sleep quality? Yeah, I suspect he is probably sleep deprived.

Obviously, my dad used to do that. And until I lost some weight, I did it as well. My dad used to fall asleep, you know, in cinema, the theatre, at the dining, you know, during dinner sometimes pretty much. And if he ever sat down, you know, he'd sit down on the sofa, he would fall bang like that. So I suspect it's less to do with Radio 4 and more to do with the fact he's probably quite sleep deprived. I don't know anything about her dad, but I would wonder if perhaps he's got a little bit of a little bit of a bigger waste going on. Sleep apnea is one of the communist cause, particularly in. men for disrupted sleep, it's like snoring, but even worse.

You kind of go, and then you stop breathing for periods of time. And very, very common, massively underdiagnosed. They know particularly with fire officers, police officers, around a third of them suffer from sleep apnea. And indeed, it is the leading cause of death in people who do particularly shift work because they're eating unhealthily, they put on the weight. and then they have this thing sleep apnea where they stop breathing. It is immensely curable.

You just need to lose weight. If you can lose around five to six kilos, then that will have a major, major impact on the quality of your sleep and on your breathing. Beyond that, there are things like CPAC machines. But going back to the original question, I think once you are asleep and the soothing sound of Radio 4 has put you in sleep,

then to be honest, matter what's going on as long as they, you know, nobody's kind of shouting or doing something disruptive. There's quite a lot of research into different types of noise, pink noise, white noise, black noise. I go into that as well. And these are different types of noise. So for some people, it's the sound of sort of tinkling waters, others. There's a more sort of coming and going noise, which is known as pink noise, which seems to be quite effective, which is more. a sort of natural noise. And others, it's just kind of blocking out, almost a...

So it's worth kind of exploring different types of noise, but I'm not sure Radio 4 is any worse or really better than anything else. I mean, for a while I was sort of setting up my phones that it would play some music or sort of I liked ocean sounds to get to sleep. But I was using my phone then while I was in bed. And is that a problem with regards... I've read about blue light, Is it a problem for me to be looking at my phone while I'm in bed?

Well, I think the blue light thing, certainly as far as phones is concerned, is a myth. Your phone is not going to be emitting anything like enough blue light to wake you up. I will keep you awake unless you're really, you know, set it on intent. I think it's mainly a marketing device so people could sell devices to, you know, filter out the blue light. So I think that is a top myth. The thing that mainly is a problem with phones and laptops and stuff like that,

is not the light, it's the distraction. It's the fact the whole point of social media is to grab your attention. And my daughter, for example, who's 20, once she's on social media, you know, she's doomed. So she has to leave her phone outside the room. Otherwise, she will start, you know, once she's watching something, it doesn't stop. Or once she started following something, it just doesn't stop. And that's exactly how these things are designed to hook you up, keep you addicted. keep you going. So it's nothing really to do with the light. Much more to do with the addictive

nature of the material. So if you've got it there and if you can ignore your emails and stuff like that and you're just listening to sound, then that is not a problem. The risk is that if it is within hand reach, you'll think, oh, I must just check up the latest on COVID-19 or whatever it might be. And before you know it, the hours have drifted you to buy. You'll be delighted to know, of course, the fast asleep is available as an audiobook. And I'm sure that will you to sleep. Is it narrated by you? It is narrated by me.

My dulcet tones will be very soothing and calming and sleep, sleep, sleep. Yeah. That was Dr Michael Mosley talking all about sleep. His book, Fast to Sleep, is out now. If you want to watch the full interview, head over to our Facebook page, and to find out what our next book is and to join the Q&A session with its author,

head over to sciencefocus.com forward slash science book club. The new issue of BBC Science Focus magazine is out now, where we look at the missions planning on building a permanent base on the moon by 2030, and as ever, there are loads more of features inside. So head over to ScienceFocus.com to find out how to subscribe. And please let us know what you thought of the episode with a rating or review wherever you listen to your podcasts. Thank you. Thank you for listening to the Science Focus podcast from the BBC Science Focus magazine team. With the UK's best-selling science and technology monthly, available in print and in several

digital formats throughout the world. Find out more at ScienceFocus.com or look out for us in your app store. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music can be lost through digital sources or poor signal. Name Audio believes you can have digital precision with analog warmth. Alongside French acoustic specialist Focal, Name creates high-end audio systems combining innovation with craftsmanship, so you can listen to music, just as the artist intended.

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