Instant Genius - Synchronizing your body clock, with Prof Russell Foster

Episode Date: April 9, 2023

Your body clock, or circadian rhythm, doesn’t just influence your energy levels throughout the day. Recent studies have revealed that your internal timekeeper also has a significant impact on your bodyweight, immune system, mental health, sleep quality and more. How can this be possible? And what are the simple things you can do to live more in sync with your biological timepiece? To answer these questions and more, we’re joined by Russell Foster, professor of circadian neuroscience at the University of Oxford and author of Life Time: The New Science Of The Body Clock, And How It Can Revolutionize Your Sleep And Health. Learn more about your ad choices. Visit podcastchoices.com/adchoices

When you need to build up your team to handle the growing chaos at work, use Indeed sponsored jobs. It gives your job post the boost it needs to be seen and helps reach people with the right skills, certifications, and more. Spend less time searching and more time actually interviewing candidates who check all your boxes. Listeners of this shell will get a $75-sponsored job credit at Indeed.com slash podcast. That's Indeed.com slash podcast. Terms and conditions apply. Need a hiring hero? This is a job for Indeed sponsored jobs. This episode is brought to you by Subaru. Go further in a long-range Subaru hybrid with up to 581 miles per tank in the Forrester Hybrid,

longer range, better fuel efficiency, and legendary symmetrical all-wheel drive standard. The Subaru Forrester Hybrid. Visit Subaru.com slash hybrid to learn more. Maximum range based on EPA estimated combined fuel economy and a full tank of fuel. Actual mileage and range may vary. Introducing the new best skin ever, ultra-slim, Precision Concealer from Sephora Collection. It's full coverage with a matte finish and perfect for any look,

whether you're building it up for a full glam moment or targeting correction for a more natural vibe. At only $12, it's great for affordable touch-ups on the go. Get this new must-have concealer at Sephora or at Sephora.com today. This podcast is sponsored by name, audio, and focal. Streaming has made music more accessible than ever, but true listening is about more than ease. It's about quality.

British audio experts name audio, alongside French acoustic specialist focal, combine handcrafted tradition with cutting edge innovation and high-end materials, delivering digital precision with analogue warmth. So you can experience exceptional sound at home. Music just as the artist intended. Visit name audio.com to learn more. Oh, and welcome to Instant Genius,

the bite-sized master class in podcast form. I'm Thomas Lynn, digital editor at BBC Science Focus magazine. You probably know that your body clock has a large influence on your energy levels throughout the day. However, recent scientific studies have revealed how your body clock also has a significant bearing on your body weight, immune system, mental health, sleep quality and more. How can this be possible? And what are the simple things that you can do to live more in tune with your biological timepiece? To answer these questions and more, I'm joined by Russell Boster, Professor of circadian neuroscience at the University of Oxford,

and author of Lifetime, The New Science of the Body Clock and How It Can Revolutionise Your Sleep and Health. Hello, Russell. Welcome to the show. Great to meet you, Thomas. I'm really delighted to join you today. Fantastic. So I'm going to start with the big question. And I know, that the term body clock is thrown about quite a lot in the science world. But what does it mean? What actually is somebody's body clock? Okay. If we think about what our biology needs to do, it needs to deliver the right stuff, at the right concentration, to the right tissues and organs,

at the right time of day. And if we don't do that, our systems fail. And you can think of the body clock or the circadian system as being key at sort of organizing all of that biology in both time and in space. Now, if we look into the brain, there is a master clock within the brain called the supra-chaismatic nuclei. And what done is the work I did when I was first in the States was trying to identify this brain structure as this master clock. And it comprises in humans about 50,000 cells. And what's so cool is you can take one of those cells. And what's so cool is you can take one of those cells out, and you can look at it in a dish, and it will show a 24-hour oscillation. It's a cellular clock. And I have to say, when we first started, we thought that the clock was the product of

cell-cell-cell interaction. It was an output of neural circuitry. But now we know it's a subcellular, molecular feedback loop. And that, you know, the Nobel Prize in 2017 was given to the people who first showed how the clock ticked in the fruit fly. And what's remarkable, is what you find in the fruit fly is pretty similar in us. The same basic building blocks exist across all of the animal world. So we have this representation of an internal day within the brain. It's no use having a clock unless it's set to the external world. A classic mismatch between internal and external time is jet lag.

And the way we get over jet lag and the way we adjust our clock on a daily basis is exposure to the light-dark cycle. And in fact, much of what I've been doing over the past few decades has been understanding how the eye detects light to regulate internal time. So you've got this sort of eye master clock within the brain axis. And we thought that's what would happen for years and that the signals from the master clock would then just drive rhythmic physiology, whether it's hormone outputs, whether it's behavior, whether it's appetite, whether it's digestive systems, whether it's immune function. And then we discovered, and in fact not me, but Uli Shibler, and this I can remember when I sort of saw these data emerge at this fantastic scientific meeting, showing that basically every cell in the body has a capacity to generate a 24-hour rhythm. So it's not, and with the shorthand is, oh, the clock, but actually it's not the clock. It's an entire circadian system where a master clock in the brain is coordinating billions and billions of individual.

cellular oscillators, organized throughout the systems of the body. And so it's an entire temporal structure that is coordinating our response to a rhythmic world, you know, the rotation of the earth on its axis. So just to clarify, it's not sort of one physical, almost body clock inside someone's head. It's more of a system of systems, so to speak. Yes. Although what's fascinating is that the clock in the brain in the supra-chiosmatic nuclei seems to be fundamentally built in the same way as the clock you'll find in a liver cell or a gut cell or whatever or a muscle cell. And so the basic system has been preserved, which is also, I think, fascinating. So what makes the clock in the brain so important then if all cells have the same characteristics?

That's a really good point. And of course, I think the analogy would be an orchestra. You've got the conductor in the brain producing a regular temporal beat from which all the component parts of the orchestra take a reference cue. And if you shoot the conductor, then all the musicians of the cells of the body start playing at a slightly different time. And instead of having a glorious biological symphony, you have a sort of a biological cacophony, where you can't do the right thing at the right time. And biology begins to fall apart. And in fact, in many diseases, that's what you see, that the various organ systems and the cells within those organs, are starting to drift apart and not produce a coordinated response,

but essentially it becomes a sort of a time smear, temporal smear. So I think I might know the answer to this, considering you are saying that the biological clock impacts almost all cells in our body, how important is the body clock to our health? It's about as important as it can get. I mean, you name a system, and it's being up and down-regulated,

by a circadian system. And one thing that's emerged fairly recently is the immune response. So what we now know is that as we approach sleep at the end of the day, the immune response it sort of starts to get sort of turned down. It's less, as it were, aggressive. And it's sort of turned down overnight. But when morning comes and we're out there running around interacting with others, it's turned up.

So for example, if you're going to be vaccinated against the flu virus, then the data show that morning vaccination is much more effective than afternoon vaccination. Same, same vaccination, you know, against the same antigen, is going to be much more effective in the morning compared to the afternoon. So you could ask the question, well, why? Why? Why not have the immune system on full throttle? And we don't know the answer to that, but the suspicion is that if you had the immune system on full throttle all the time, then you'd be much more vulnerable to autoimmune responses. So it's turned down when we're less likely to encounter new pathogens when we're asleep and then turned up when we're moving around our environment, meeting other individuals and

other bugs within the environment. So it's one example of sort of this adaptive response. It's all about doing the right thing at the right time. Same for digestion, same for thought and our ability to come up with solutions to complex problems. It's incredible for adults. problem-solving abilities peak at around about 11 o'clock, 12 o'clock in the morning, late morning, early afternoon. That's for adults. For teenagers, it's delayed by two hours, and we might want to discuss why that is. But by 5 o'clock, 5 a.m. in the early hours of the morning, our ability to process information is as impaired as if we'd consume sufficient alcohol to make us legally drunk. That's the level of impairment that you have. And so everything's being up and down

regulated in response to this dynamic world, this sort of earth that revolves once every 24 hours. It'd be great to get into the best time to do certain activities, but should probably ask first, will these times be the same for every person? So does everyone have the same body clock? That's really fascinating. No, we don't. Each of us has a chronotype. We, we have. Each of us has a chronotype. which is sort of a body clock type, and it's been very easily described as morning people, so larks, intermediates, doves, and then owls, which are the evening people.

And that arises because of three important interactions. One is your genetics, so by their contribution to our genes, our parents are still telling us what time to get up and go to bed. But there's a very, you know, there's some really nice data has emerged that, you know, it's even subtle changes in some of those key clock genes. can predispose you to morningness or eveningness. The second factor is your age.

So from about the age of 10, there's a tendency to want to go to bed later and later and later. And it peaks late teens, early 20s, when we are at our most late. And interestingly, males tend to peak later than females, and they tend to be later than females. And then there's a slow move to the time you get to your late 50s, early 60s. we're getting up and going to bed at about the time you got up and went to bed when you were 10.

And that line of sharp increase over the years of puberty and the slow move to a more morning chronotype is associated with hormonal changes, specifically the sex steroids, estrogen, progesterone and testosterone. Point being is the when time you're in your late 50s, early 60s, you're getting up and going to bed about two hours earlier than you would when you were in your late 10. early 20s. So there's genetics, there's age and hormonal profiles. The third is the one that's often overlooked, and it's the one we have control over, to some extent, which is when we see light. We talked about light being so important to set the internal clock to the external world,

but in fact, morning light and evening light do opposite things. So morning light makes us get up earlier and go to bed earlier, whereas evening light makes us go to bed later and get up later. So when we're all agricultural workers, you know, and out getting the sort of dawn, dusk signal, it was perfectly symmetrical. And we sort of be nudged backwards and forwards. Now, because we live in dimmed dark caves in our buildings, we don't necessarily get symmetrical light exposure. And we did a study a few years ago. It was on university students around the world. and we showed that the later the chronotype, the less morning light they got, which would make them get up earlier, and lots of afternoon evening light which would make them get up later. So if you happen to be a really terrible owl, to some extent you can advance your clock by setting the alarm.

It's brutal, because I am an owl. It's brutal. You get up and you expose yourself to bright morning light either naturally, ideally or from a light box, and that will move the clock forward early in time. So there's these three factors, genetics, how old we are, and when we see light. How can you actually tell what chronotype you are? Is it just simply how are you feeling, or is there a way to get assessed? Yeah, there are standard questionnaires. And in fact, in the back of Lifetime, the book I wrote fairly recently, there is a questionnaire

because so many people are interested, you know, am I a lark or an owl? Most of us, 65% of us are somewhere in the middle. But there are extreme larks and extreme owls. and there are questionnaires. There's a number of them which have been very well validated, and they basically ask you, given your preferred bedtimes and wake times, when would they be? And they give you a range. Or, you know, when you are forced to get out of bed in the morning, do you wake up fully refreshed or does it take you a long time to wake up? Those are the sorts of questions that you will be asked.

What are your favourite chronotype quizzes available online? Have you seen any that you think are quite good? Yes, the best, I think, is the Munich Sleep Questioner, which is an online questionnaire, which I think is extremely good. It's a slightly different one because what it sort of does is ask you what you'd like to do on work days versus free days. And, of course, that can have a big impact upon the sorts of decisions you make. So I think the Munich Sleep questionnaire is probably my favourite. The most sort of used over the past 20, 30, 30 years has been the Horn Osberg, which is the one I put in the back of the book. You're great of protecting your data, but lots of places could still expose you to identity theft. I thought it was safe.

If that happens, LifeLock gives you a US-based restoration agent who will stick by your side from start to finish. Phone calls, filing documentation, preparing insurance claims, your agent handles it all. In fact, we're so confident Restoration is guaranteed pour your money back. Isn't it nice to have someone like that on your side? Save up to 40% your first year at LifeLock.com slash Spotify.

Terms apply. You said this place was steps from the water. We just haven't found the steps yet. How much did we save? Enough. Enough to get lost. Or you could book a stay with Hilton. Welcome to your ocean front room.

Just steps from the water. The Hilton sale on now. Book on Hilton.com or the Hilton app and save up to 20% to get the stay you expected. When you want savings, not surprises. It matters where you stay. Hilton, for the stay. This podcast is sponsored by Name, Audio and Focal. With over 100 years of combined expertise, Name and Focal have been bringing music to listeners just as the artist intended. Since day one, This mantra has shaped every innovation in hi-fi design, technology and acoustic engineering, balancing craftsmanship and tradition with pioneering thinking.

Name Audio pushes cutting-edge technology to ensure digital precision whilst sustaining Pratt, pace, rhythm and timing, the elusive quality that makes music feel alive and gives it emotional texture. Today, in partnership with French acoustic specialist's focal, name audio creates systems that deliver exceptional sound and unforgettable listening experiences at home. Try it for yourself at a focal powered by name boutique. Visit focal powered by name.com for more information. So once you identified your crinotype,

can you change it? So can you change from being a night owl to a morning lark? Can you reset your body clock, so to speak? Not really, no. I mean, you can, of course, you can, you know, the genetics is fairly fixed. The hormonal profile, you know, is fairly fixed. But what you can do, as I say, is, is nudge it in the right direction by using more or less morning or evening light. And that, that actually does work and has been shown to be effective.

So how practically could somebody do that, say, particularly if they're trying to get up earlier and there's simply no daylight available at the time? Or if someone is trying to avoid some lights, should they be wearing sunglasses all the time in the morning? Yeah. So trying to make yourself more of a morning type. And of course, that's tricky during winter. And certainly the further north you go, the more difficult it becomes.

I mean, if you're living in Tromso in northern Norway, there's two months of darkness. And, you know, the family often troop into a room in the morning with light boxes on full blast, you know, where they have their breakfast. So they get their, you know, their photon shower first thing in the morning, which helps set the clock. And that can be the same for us living at lower latitudes. I mean, we can sit in front of a lightbox where we have our breakfast. But that's really just in the extreme winter.

Most of the time, it means that we get out and get morning light exposure. Interestingly enough, there was a study which was suggested that dog owners have a better and more robust sleep wake cycle. And I don't think that's because they're companion animals. I just think it's because you have to get out and take the dog for a walk first thing in the morning. And that gives you your, and the dog, of course, your morning synchronization. So I think it's that morning light that is so very important. So if you want to be more of a morning person, get a dog. Well, yeah, well, I mean, I think it's probably cheaper to get a light box, but that could be one solution.

Just don't get a cat. No, don't get a cat or hamster, for example. What is the best time of the day to exercise? Well, that'll depend to some extent on your chronotype. And there are two strategies here. Because the nighttime physiology, sleep physiology, and the daytime physiology are very different. So, for example, during the day, we're taking calories

and our activity is either burning those calories up or we're laying them down to fat. But at nighttime, of course, we're not taking calories in. We're mobilizing the calories, the stored calories. So one strategy is you get up and you do your exercise before breakfast, which means you're burning up your stored calories. The problem is that our ability to exercise in terms of the length of exercise and how vigorous we can be increases throughout the day. And it peaks in the late afternoon early evening.

So what you could do is either exercise first in the morning, get those burnt calories, burn up those stored calories, or you exercise later in the day, and you can exercise for longer and more vigorously, and that ensures that you burn up the calories that you've taken in, so they're not lying around, and that when you go to sleep, they're not sort of, or as you go to sleep, they're not converted to,

into fat. So there's two strategies, first thing in the morning or later in the day. And actually, again, going back to chronotype, it's been showing that athletes, really fascinating, that the owls are far more effective at a vigorous exercise in the late afternoon, early evening, compared to earlier in the day. And it's interesting that most Olympic finals and things tend to be late afternoon, early evening, because that's when people, on average, are able to sort of exercise most vigorously. So, yeah, it depends upon what you want to do. You sort of mentioned it before, but what's the best time of the day to make a big decision or to be on points in terms of your mental processes?

So if, say, someone was a journalist who had to write a piece about how the body clocks impacting someone's health, when would be the best time for said journalists to, get that sorted? Well, there's two components to that answer. One would be on average adults, their cognitive abilities, their ability sort of, you know, make sums or sort of answer questions or reaction times, that sort of late morning, early afternoon. As I say, teenagers tend to be delayed about two hours. So earlier in the day, however, there's some very nice data showing that a night of sleep can enormously enhance your ability to come up with novel solutions to complex problems. There was a fantastic study by Jan Bourne and his group a few years ago.

Jan developed this task that people had to perform. And he gave it to one group in the morning and they had to perform the task, introduced to the task in the morning, they performed it that afternoon. And about 20% of the group solved the problem. Next group introduced in the morning. morning, performed it the following afternoon, but they weren't allowed to sleep at all. And about 20% solved the problem. Of course, this is the exciting data. You know, third group introduced in the morning, performed at the following afternoon with the full night of sleep.

60 to 70% solved the problem, you know, showing that a night of sleep is not simply allowing you to retain and develop memories, which we're kind of familiar with, but it's also the processing of information, coming up with innovative solutions to complex problems. So if you are a journalist and you wanted to sort of to be at your peak, certainly introduce yourself to the topic the night before, sleep on it and perform it the next day, probably sort of around about noon or so. One of the things that's quite fascinating, we talked about teenagers being delayed somewhat by about two hours. And I think it's fascinating that our educational systems still put the so-called most demanding subjects, like maths and sciences first thing in the morning.

And it's been shown that if those lessons are pushed later in the day, then more is retained by the students. And in fact, exams later in the day, students do better. So what's the contradiction here? Why this conflict? Well, it's straightforward. The teachers tend to be adults. They're full of, you know, vim and vigor and bounce into the classroom first thing in the morning and feel capable of teaching these demanding subjects, but these students are still waking up. So there's a genuine temporal mismatch between students and their teachers. How much would someone's chronotype influence how well they might do if they were, say, sitting an exam in the afternoon? Is it only going to vary by a few hours or something more?

Because on average, teenagers tend to be later chronotypes, not all, but on average, then it has been shown that if you start the school day later, and this has been done in the United States, where the school day, of course, can start at 7.30 or even 7. So, you know, young people are getting up really early to get the school bus to get to school. And so now the Californian school district has said, but haven't enacted yet, I don't think, that the school No school should start lessons before 8.30 in the morning. And it's been shown that that has better educational outcomes, less depression, less self-harm, less truantism. Can we extrapolate to the UK? I don't know if we can, because, of course, the school day for the UK starts at 10 to 9 or 9 o'clock. So we're half an hour later than the recommended start time in places like California and other places in the States.

What we have shown is that working with teachers to give their students information about the importance of sleep in circadian rhythms, so we developed, you know, eight, 30-minute sessions delivered by the teachers. And in those students showing levels bordering on clinical insomnia, so really quite poor sleep. And that was about 20 to 25%.

The education, at least short-term, improved their overall feelings of well-being and their sleep-wake cycle. So education, I think, can be a very powerful tool in this space. And I do think while we're on the subject, it's absolutely crazy. You know, a third of our biology is sleep biology. Every aspect of our health is regulated by a circadian clock, and yet there's no formal instruction about the importance to our health and well-being within our school system.

And I just don't understand why it's not embedded in the curriculum, in the same way that sex education and personal hygiene and all of those other issues are. So if you were going to implement this in the school curriculum, what would you teach about when to eat? When's the best time to eat it in the day? When is the best time to have your sort of heaviest meal? That is again a fascinating topic. It's worth bearing in mind that the way that we as a society taking our calories has changed hugely. In 1,100 breakfast, was the main meal of the day. And you had the big breakfast

before you went out and worked. By the Tudor times, it was sort of 11 or 12 o'clock, so it had moved to more lunchtime. And so we think of those great Tudor banquets. They were not here in the evening. It was sort of tended to be during the middle of the day.

And so as modernity had advanced and industrialization, and because we now no longer work and live in the same space, we've separated that. So the longer and the longer commutes to work have meant that many people don't have time for breakfast. They skip breakfast. The demands of work mean that you may get a sandwich sitting at the computer screen or whatever.

And then finally you get home, ravenously hungry, and stick the ready meal in the microwave. And that's when you have your big, caloric intake. And the biology hasn't shifted with this later eating time. In fact, if you give the same amount of glucose to individuals in the morning at lunchtime in the evening, the clearance of that glucose, you know, the extent to which it's metabolized and packaged up, is rapid in the morning, okay at lunchtime, but poor before you go to bed. And, of course, high levels of circulating glucose later in the day predispose you to a greater risk of type 2 diabetes, metabolic abnormalities, obesity. and of course all the consequences associated with that. So really we should be eating earlier in the day and not later in the day. And we are not showing any real signs of shifting back to what was happening in the pre-industrial era

when, as I say, most of us ate earlier in the day. I mean, I can remember my grandparents, you know, having a major breakfast and a big lunch, but a much, much lighter dinner or tea time. And so we've gone very rapidly, in two or three generations, eating habits have changed dramatically. For the worse, I'm afraid to say. So could having a big dinner impact somebody's sleep? It might do in the terms, in the sense that a large meal before you go to bed can produce gastric problems, which can make it uncomfortable and therefore less likely to get off to sleep. Yes, that can be an issue.

and certainly ulcers and things like that play up worse at night. And sort of acid reflux can be a big issue. So people lay down. And of course, then there's much more a chance of acid sort of passing from the stomach into the esophagus. So, yes, that's another good reason why you would limit your food intake in the evenings. What about taking medication? When is the best time to do that? It will vary enormously depending upon the type of medication that you're taking.

So we've talked about vaccination being more effective in the morning rather than later in the afternoon. Some very interesting work, which is slightly controversial, but I think in a broad sense, it's true, is that if you're taking an anti-hypertensive because you've got high blood pressure, there's a study published a couple of years ago, suggested taking it before you go to bed, rather than first thing in the morning is much more effective. And in fact, over something like a 10-year period, it can halve your chances of having a stroke. Now, how does that make sense? Well, the first thing to be aware of is that there's a 50% greater chance of having a stroke between 6am and 12 noon. And that's the same for a heart attack. And that fits with, you know,

you're in a reduced sort of a blood pressure state, you're preparing for active. so the clock is then driving up blood pressure, you're then active. And so, you know, you get this massive rise in blood pressure. Now, if you're healthy, that's not an issue. But if you're hypertensive, then that can be a real issue. And so the time you've actually woken up and taken your medication, you're in the middle, towards the end, potentially, of that really risky phase, of that 6am to 12 new window. But many of these anti-hypertensives, these drugs, have a long half-life. So if you take them before you go to bed, they're hanging around an insufficient concentration to actually hit that surge in blood pressure that would normally occur first thing in the morning.

So you have to understand the underlying temporal circadian biology to know when best to take drugs. Where we have some very clear data is in different forms of cancer. There was a famous study on childhood leukemia, oh, quite some years ago now. I've made. maybe 20 or more years ago, showing that when the children were given their chemotherapy late afternoon, early evening, there was a much greater chance of survival versus taking the chemotherapy first thing in the morning. It was something like 75% survival versus 35% survival over, I think it was a four or five year period. So that's a big deal. Ovarian cancer, again, same drug, same concentration at different time. And it went, if I can remember,

remember the details, essentially after five years, 40% of the group were alive with one time versus 10% at another time. So it really emphasizes because our biology is so completely dynamic, it's doing different things at different times of the day. No great surprise that the medications that we take will also have a different effect across the day. And this whole area of chrono-pharmacology, people are beginning to be aware of it, but it's not routine in clinical practice. What about sleep, sort of thinking about the body clock? What are the simplest things that somebody could do to improve their quality of sleep? So of course, you know, sleep is a lot more than just the body clock. You have this internal 24-hour drive saying, now you should be asleep, now you should be awake. there's also the factor of sleep pressure.

The longer you've been awake, the greater the need for sleep. And so the clock and this sleep pressure usually interact. And of course, one of the great problems of night shift work is that night shift workers do not adapt to the night shift. And so they are working when their body clock is saying, you should be asleep. So they're overriding that deep biology saying you should be asleep. And furthermore, even though the sleep pressure is huge. hugely high when they finish the night shift and they go home. Trying to sleep is a problem because the body clock is now saying, hang on, it's daytime. You should be awake. So the quality, the daytime

sleep you get as a night shift worker can be very poor. So you get the double whammy of a misaligned clock and an abnormal sleep pressure. So sleep, though, is, it's really fascinating. We're beginning to really understand the nuts and bolts and the neuroscience of sleep. But what we're one of the, I think, really important issues is that most individuals won't have a sleep problem at all. I mean, clearly there are clinical issues about sleep, but most of us will be either anxious or stressed, and that will interact with our abilities to sleep. I mean, just a simple example. It's always assumed that, you know, the perfect night of sleep is this eight hours of uninterrupted sleep. And that's actually, that kind of nonsense was part of the reason I wrote

lifetime because it ignores the fact that people are incredibly variable. And a healthy sleep may range, you know, some people as low as six hours, some people may need 10, 10 and a half, maybe even 11 hours. And we each of us have to work out what our optimum sleep needs are and then defend those sort of sleep behaviors. So sleep duration is enormously variable. We've talked about sleep weight timing once chronotype can change. But what happens as we age and we.

we tend to wake up more. We're often told that we have to have this uninterrupted sleep, but that's also nonsense. We go through a cycle of a REM, non-REM sleep cycle, and we almost wake up every 70 to 90 minutes or so. Many of us actually wake up and then we fall back to sleep again. But some people wake up and are anxious and stressed, and that then stops them getting back to sleep. The other thing is that the default position of human sleep, is what's called biphasic or polyphasic, which is where you wake up, you may interact with others, you may go back to sleep again, you may wake up again. It's not a consolidated eight hours. And so when people don't know this, they think they wake up and think, oh my goodness,

that's it. I must have start doing my emails and start drinking coffee. And of course, if you stay calm, keep the lights low, maybe a few pages of Jane Austen or Radio 4 extra. just something relaxing, and then you will fall back to sleep again. That was Russell Foster, Professor of circadian neuroscience at the University of Oxford, and author of Lifetime, The New Science of the Body Clock, and how it can revolutionise your sleep and health.

Thank you for listening to this episode of Instant Genius, brought to you by the team behind BBC Science Focus magazine, which you can find on sale now in supermarkets and newsagery, as well as your preferred app store. You can of course also find us online at ScienceFocus.com. 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 cross-brose. So you can listen to music, just as the artist intended. Discover more at name audio.com. Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals, because we're built for what you're building. Fit for your ambition for Citizens Bank. Relax and let Ralph's delivery handle your grocery shopping this week.

We start with only the freshest items, then review your list and carefully choose each Then we pack it all up and deliver it in as little as 30 minutes so you can feel confident it's what you ordered. Fresh groceries, your way, with Ralph's delivery and pickup. And right now, you can save $20 on your first delivery or pickup order. Ralph's, fresh for everyone.