The Sleep Scientist (NEW RESEARCH): Sleeping Patterns Can Predict Future Diseases! Sleep Deprivation Is A Silent Killer! The Painful Trick To Fix Poor Sleep - Dr Guy Leschziner

You're listening to this podcast. So I know you've got a curious mind. Here's a helpful fact you might not know yet. Drivers who switch and save with progressive save over $900 on average. Pop over to progressive.com, answer some questions, and you'll get a quick quote with discounts that are easy to come by. In fact, 99% of their auto customers earn at least one discount. Visit progressive.com and see if you can enjoy a little cash back. Progressive casualty insurance company and affiliates. You can also use a cash back. He was a trained teacher at the university. [Music] Guy. Shall I say "Dr Guy"? What is it that. Is it the very sort of heart of your personal curiosity? Because as I look at your work and what you've committed your career to, there seems to be a bit of a through line as to sort of the subject matters that have captured you. So I've always been fascinated why we are the way that we are. And obviously from a scientific perspective, the core of that is our brain. And in the course of my clinical practice, I come across a whole host of individuals who really sit at the extremes of the human experience. People who are sometimes afflicted by very serious neurological conditions who experience the world in a very different way to how we do. So really the core of what I do, particularly in the public facing work that I do, it's looking at those people at the extremes of the human experience and trying to work out what it tells us about all of us, about how we all work. When you say the extremes of the human experience, what does that mean? So individuals who see the world in a very different way, experience the world in a very different way, understand the world in a very different way. So you know, from when it comes to individuals who have very extreme sleep disorders, to individuals in whom the perception of reality is very different from our own, or to people who behave in a very different way. So when it comes to things like aggression or the way the relationship with food or their personality traits, I think in every area of clinical neurology, you see individuals in whom something has happened to their brain that fundamentally changes the way they see the world, interpret the world, or behave within that world. And what's your sort of day to day? And if I was to take a look at your CV, what would I see on your CV? I studied medicine at Oxford and then at Imperial, and very early on in my career, I started training in the world of neurology. Did a PhD at Imperial and Cambridge? What is neurology? Neurology is the clinical study of the brain. So the brain in its disease state. So we see individuals with epilepsy, with Parkinson's disease, with nerve problems, with certain types of sleep disorders. Basically any disease or disorder that influences how the brain and the nervous system works. So I did a PhD at Imperial and Cambridge looking at the genetics of epilepsy and then started working as an NHS consultant in 2010. And you're a consultant of neurology and sleep medicine? That's right, yeah. I've never heard the phrase sleep medicine before. Well, sleep medicine has been around for a long time. I was very lucky in that early on in my training period, I rotated through a hospital where one of my now colleagues had actually come from the United States. He'd been based in LA where sleep medicine was really starting out. And he'd set up a sleep medicine unit. And that was at St. Thomas's Hospital in London opposite the House of Parliament. And certainly over the last 20 or 30 years, there's been a really exploding area of medicine. But partly mirrored by the fact that we are much more aware of the impact of sleep on a range of biological and mental health issues. But actually in the world of neurology, there are many sleep disorders that have their basis in the brain. Conditions like narcolepsy, like people who sleep walk or act out their dreams. People who have episodes at night that may or may not reflect certain types of epilepsy. So that's really the primary focus of my work now. Between 2013 and 2023, you ran Guy in St. Thomas's Hospital Sleep Disorder Centre. That's right, yeah. What is that? So the sleep disorder centre is probably one of the largest sleep disorder centres in Europe actually. So we have 10 inpatient beds. So every night, 10 people are brought into the sleep laboratory. And we study their sleep. It's got now about 15 consultants. It's got a staff of about 50 people. And we see a range of people with conditions like sleep apnea, which is where people stop breathing at night. And then some of the conditions that I've talked about, conditions like restless leg syndrome, extreme sleep walking, narcolepsy, another related issues. How many patients have you had in your sleep disorder centre that you've studied? Gosh, an awful lot. So we do about 2,500 sleep studies a year. And we've been going for, well, a long time, sort of 15, 20 years. So every year we see about 10,000 patients in total. So very, very large numbers. If you had to estimate how many you've seen? I would imagine somewhere in the region of upward of 100,000, if we're talking about 10,000 patients a year. And how many sleep studies have you conducted in that centre? So we've been at the current site with 10 beds for about 10 years. And so we're probably talking about 25,000 studies. Why sleep? Of all the things that you could commit so much of your time to? Because it appears you've been really thinking and working on the subject matter of sleep for about 20 or two decades. - Yeah. - We're actually something like that. What, why? Well, I think the first thing is that we spend a third of our lives doing it. And yet we, whatever people like me will tell you, we still understand relatively little about it. We understand relatively little about what it's for, what it does to our biology. Obviously that's changing very, very quickly now. It has a great deal of overlap with the world of clinical neurology. So I also do, I do specialist clinics in epilepsy and I do specialist clinics in general neurology. And sleep and the brain intersect to every single level. Of course, you know, it's not me saying this, but a famous statement is sleep is of the brain by the brain and for the brain. It's intimately linked to every aspect of how our brain works. So one of the really exciting things is that because it's a relatively new area or understanding of it is exploding in ways that are not paralleled across other areas of clinical medicine. Is it important? Yeah. I think it is of fundamental importance. You know, the fact is that if sleep wasn't important. it would be a very stupid thing for evolution to create in us, the fact that we are essentially switched off from our external environment for a third of our lives. And actually there's a whole host of evidence when you look at how certain animals have developed the ability to be able to sleep with only half their brain at a time, you know, animals like aquatic mammals or certain birds and dolphins. That very much suggests, well, you know, that must be of great importance if it's, if sleep is a risk for our survival, because if you're an aquatic mammal like a dolphin and you're sleeping and you're unable to surface or unable to see what predators are around you, that the evolution has designed a system where by it enables you to sleep with half of your brain at a time. So that in and of itself tells us it's important that the fact that the circadian rhythm, so that 24 hour cycle that a whole host of biological rhythms have is so intrinsically linked to life itself that actually every single life form exhibits features of this 24 hour circadian rhythm tells us that this was something that was prioritized at a very, very early stage in life. So yes, it's important and over the last few years we've understood understood precisely why it's important I say precisely, but we know that it's important for pretty much every aspect of our waking lives be it our immune system be it our cardiovascular system or blood pressure risk of diabetes mental health, so depression and anxiety, even how we perceive pain, so it really is fundamental to every system that we rely on during our waking lives. Having seen, you know, thousands and thousands and thousands of people that struggle with sleep that have been sent to your center, do you think the average person on the street over or underestimates the importance of sleep in their day to day life? Well, I think it's changing. I think it was not that long ago where you know comments like sleep is for wimps was heard fairly frequently and that there were some bragging rights associated with how little you sleep. I think that there has been a transformation over the last sort of 15 or 20 years whereby people have become much more aware of how important sleep is and have started prioritizing it a little bit. So you think, well, where do you think we stand then overestimate, underestimate? I think that there is still in the general population and underestimation of how important sleep is, but I think there are certain segments of the population that are much more aware of it and perhaps even dare I say overestimate it. Overestimate it, yes, I think so. I think that there is a danger at the current time that we tend to obsessionalize about sleep and think that it is the be all an end all is. I think that there is a lot of a part of normal life for our sleep to fluctuate depending on what's going on in our external and our internal lives. And I think the danger is that if you overemphasize the importance of getting eight or eight and a half hours sleep every night, then you actually risk problems later down the line exacerbating things like insomnia. Can you give me a view of the current state of sleep in terms of the percentages stats of people that are struggling with their sleep, the variety of ways that we struggle with our sleep, the different disorders associated with our sleep and just like a breakdown of society at largest current sleep health. So we think that about 20% of the adult population are chronically sleep deprived so that they are not sleeping enough and that's largely as a result of lifestyle factors and lack of prioritization of sleep. We think we know that about 30% of the adult population in any one year will experience a period of insomnia. So insomnia is different from chronic sleep deprivation. Insomnia is the state whereby you want to sleep where you're lying in bed and you can't sleep which is very different from burning the candle at both ends. And about 10% of the adult population will have chronic insomnia so that's an ongoing issue with not being able to sleep for more than three months at a time. So very, very high numbers. There are some other sleep disorders that are incredibly common so a condition called obstructive sleep apnea which is essentially part of the spectrum of snoring but in obstructive sleep apnea your airway narrows, you have difficulty breathing it partially obstructs and you have recurrent brief awakening sometimes that you're not aware of that disrupt your sleep. And estimates were very wildly depending on where in the world that they've been done but I think you know our best guess is something like 10 to 12% of adult males experience sleep apnea clinically significant sleep apnea and somewhere in the region of about 6% of women experience clinically significant sleep apnea. So we're talking about very, very large numbers and the majority of individuals with sleep apnea are undiagnosed so it's estimated that about 80% of people in the UK with sleep apnea don't know that they've got sleep apnea and have never seen anybody about sleep apnea. There are other conditions like restless legs syndrome which is a neurological disorder whereby people experience an urge to move a fidgetiness in their usually their legs although it can affect other body parts as well that can give rise to very huge difficulties getting off to sleep and actually staying asleep because a lot of these individuals kick at night when they are asleep and kick themselves awake. And that probably affects somewhere in the region of about 5% of the adult population even sleep walking 1 to 2% of the population so lots and lots of these conditions very, very common. How many of the people that walk in your sleep center do you think could be helped and could you help? Well, I think the majority can be helped. A cure is something different but the majority can be helped in some shape or form. And if we talk about getting someone that is walked in your clinic with some kind of sleep disorder to a state where they are a healthy sleeper, what kind of percentage do you think? Well, I think it's important to proceed what I say by the fact that actually we don't see many people with insomnia. We tend to divert people with what we turn primary insomnia or insomnia without any underlying causes to assist a service. If you look at insomnia, chronic insomnia as a whole, we know that there are some very good treatment for chronic insomnia. And actually most of those treatments are focused on non-drug based treatments, psychological based treatments. And we know that those kinds of treatments will significantly improve sleeping up to about 80% of individuals. So that's a very large number actually. And there are other treatments available. It doesn't just rely on these non-drug based treatments. There are some conditions like, for example, narcolepsy. Which is what's narcolepsy? So narcolepsy is a brain disorder that is triggered by your immune system. Is that where you fall asleep during the day? When you fall asleep very, very quickly during the day, you're excessively sleepy. You have very vivid dreams. You will often hallucinate as you drift off to sleep or as you wake up. You'll experience something called sleep paralysis where you wake up and you feel that you are completely paralyzed. You cannot move. And a lot of these individuals also experience a condition called cataplexy, which is where usually with stronger motion, like laughter, sometimes it can be the telling of a joke. And they lose muscle strength and will sometimes collapse to the ground. So it's a very pure neurological disorder because we know precisely where that area of immun attack occurs within the brain. And it knocks out a very small number of brain cells to generate this. This is a, you know, once you have it at the moment, it's a lifelong condition. But actually it can be treated. There are many treatments available. And even in the last five years also, there have been many new treatments that have become available. So actually all of these conditions are treatable. They're manageable. They're not necessary. Drivers who switch and save with progressive, save over $900 on average. National average 12 month savings of $946 by new customers surveyed who saved with progressive between June 2024 and May 2025. Potential savings will vary. Is there something at the heart of culture and how we're living? That's causing so many of us to struggle with sleep. The way that modern society is at the moment of certainty, I think is rather conducive to insomnia. in summary, or in fact, you know, when researchers have looked at pre-industrialised societies. So, you know, for example, tribes in Eastern Africa or in South America actually, insomnia is relatively rare and some of these tribes don't even have the word for insomnia. So I think that there's certainly insomnia seems to be correlated with the changes that have occurred in our society. Sleep apnea is often associated with weight gain and obviously that is very much a function of our modern societies. So yes, undoubtedly, some of these conditions can be attributed to the way that we lead our lives. Has any of it put like a sleep tracker on a tribe? Yes, that has been done. There's a chap called Jerry Siegel who is based in the East Coast in one of the Ivy League universities who has spent his life doing that. And what did he find out? So he found out that actually sleep does vary a little bit according to the seasons that they don't necessarily sleep all the way through the night, but actually their sleep is rather different to the sleep of modern society in what way? They will not necessarily, so this view that we sleep when it gets dark or used to sleep when it gets dark and wake up at dawn is incorrect. That there is some fluctuation between the seasons, but not necessarily directly related to the number of hours of daylight and that insomnia is relatively rare. So are they waking up in the middle of the night then? I think it's normal to wake up in the middle of the night. We all wake up in the middle of the night. It's very rare that you, for example, do a sleep study on somebody and you don't see periods of wake in the middle of the night. It's normal to be awake for up to about 30 minutes over the course of the night. That in itself is not a marker of pathological sleep. When I say awake, I mean, I guess I mean getting up and walking around and stuff. I think there are some individuals who do that. There's a chap called Robert E. Kirk who has spent a great deal of time looking at medieval texts and seeing how they describe sleep. He has put forward hypothesis that in medieval times people would have a first sleep and a second sleep. Now I think that theory is not universally accepted, but certainly for some individuals getting up and walking around is certainly within the realms of normality. I think there are different sleep patterns. If you look, for example, at Mediterranean Europe, the siesta culture. So people sleeping for an hour or two at lunch time, but sleeping slightly less at night. So there are a range of sleep patterns that sit within the spectrum of normality for human beings. Is there such a thing as a healthy sleep, as in, you know, see these sort of different sleep behaviors and such, but is there from a neurology standpoint or a clinical standpoint a perfect sleep or a perfect sleeping habit or, you know, so I think the first thing to tell you is that sleep is different for everyone. We know that there are genetic factors that influence, for example, your timing of sleep, your circadian rhythm, whether or not you're a morning, dark or an evening hour. There are also genetic influences over how much sleep we need. So for example, there are one or two families that I've seen in my clinical career in whom every single member of that family sleeps for four hours a night and has no ill effects and does not seem to have any long term consequences from that. They don't feel tired. There's no evidence that they're doing their physical health any harm and there have been some genes that have been identified that define that trait. Now it's a rare trait and I wouldn't suggest that most people who are sleeping four hours a night think, 'Oh, I must be genetically blessed because the reality is probably somewhat different.' So I think that in answer to your specific question, is there a perfect night sleep? No, there isn't because it depends on the nature of who you are and what your genetic inheritance is. But certainly we can say on a population basis, well, you know, sleeping somewhere between seven and eight and a half hours a night, if you look and are stressed on a population basis, we see ill effects in terms of sleeping less than seven hours or sleeping more than eight and a half hours. If you look at, for example, or cause mortality or if you look at cardiovascular disease, and now there are various potential explanations for that. Certainly if you're sleeping relatively little, we can see that there are changes in terms of how your physiological system works that might give rise to things like blood pressure issues, weight gain, cardiovascular disease, stroke, those kinds of things. What's a little bit more difficult to explain is why your mortality and other ill health goes up if you're sleeping more than about eight and a half hours. And I think that that is probably a much more complicated picture in that we know that there are certain drugs that people will be on. And when you're on drugs, that's a marker that your health is not necessarily 100% already that will make you a bit more drowsy than you normally are and will extend your sleep time. It may be that you have a sleep disorder, which is causing you to sleep more. But there's another interesting potential explanation in that we know that we are know that for example in certain diseases of the brain, there are changes to your sleep many years before, sometimes even decades before. A really good example of that is Parkinson's disease. So we know that in people with Parkinson's disease, many individuals will start acting out their dreams at night, sometimes even three decades before they then go on to develop Parkinson's disease. So is it that our sleep intrinsically changes as a precursor to certain conditions like Alzheimer's disease? And there is some emerging evidence now that actually a change in your sleeping patterns either in terms of how deep really you sleep, how long you sleep, whether or not you nap during the day, that may be a what we term a pro-dromal feature of Alzheimer's disease. Do you see anything interesting happen when someone has a baby in terms of their? I was wondering this the other day because I have a friend who's had a couple of kids and I was looking at their sleep tracker and it seems like they have this inherent ability to survive now that they've had kids on like no sleep. I was wondering if there's some sort of evolutionary mechanism that makes parents, I don't know, require less sleep. Yeah, I'm not sure I can specifically answer it. I've certainly seen a lot of people who sleep has gone to pots after they've had kids and you know a lot of people say that their sleep has never returned normal after they've survived having a couple of kids but you know what you have to remember is that the brain is a remarkable organ in that it has all of these adaptive mechanisms that enable us to cope with changes in our circumstances, changes in our environment. So if you put somebody in a sleep deprived state, sleep also changes. So what the brain does is it prioritises the very deepest stages of sleep, stage three, low-wave sleep over other stages of sleep and you know what we can see that in the sleep lab. So if somebody's very sleep deprived before they come in and we put them in the sleep lab, we see a sort of huge increase in their slow-wave sleep which is the stage of sleep that's most associated with restoration, with healing, with feeling more refreshed than other stages of sleep like for example REM sleep or dreaming sleep. So the brain is prioritising restoration faster than it would because the person sleep deprived. Absolutely, yeah. So what is the, as you were saying now, you've seen families that just require four hour of sleep and they're apparently great. Is that a lot of people? No, it's a said it's very, very rare, very rare. Because I've looked at people sleep trackers before and I've been astonished by how little sleep they seem to require but how active and great they seem to feel. And I've had this the other day because one of my fellow dragons, I said this to her, she requires very little sleep but then she gets up at 5am and goes for like a 10 mile run. And I was like, I was looking at her sleep track, I think, and you've been in bed for like five hours and you are extremely more awake and energetic than I am and you just did a 10 mile run and I'll go in bed for seven hours and it says that my stage three, stage four sleep is higher than hers but for some reason she's bouncing into the room. Well, I think there's two explanations for that. The first is maybe she is one of these genetically short sleepers, as I said, that seems rather unlikely. I think the other explanation is we know that, I talked a little bit about how genes influence our sleep. We know that there are genes that influence how resistant you are to the effects of sleep deprivation. And what I mean by that is that there are, there seem to be some individuals who don't feel or who feel less sleepy than other people when they are sleep deprived but that may be separate from the cognitive effects of sleep deprivation. So she might just not feel it. She might not just feel it but she may exhibit those cognitive effects of sleep deprivation in the same way as you or I, for example. She's 10 years older than me as well. Does that have? Well, I think that certainly we do see some reduction in sleep requirement as we get older. We're also a little bit less about, less good about maintaining sleep as we get older and that's because the brain mechanisms that stabilize sleep are becoming a little bit weaker. So this view that we need much less sleep as we get older is probably incorrect, although there is a slight reduction in sleep requirement. You mentioned earlier that when people don't get enough sleep, the chance of obesity and weight gain increases. How does that happen? What's the mechanism? So there are probably many mechanisms, but one of the ones that is best understood is that we know that when your sleep deprived, or indeed when your sleep is disrupted by anything else like, for example, sleep apnea, there are changes that occur in terms of hormone levels, of hormones that regulate our appetite and our satiety. And so even a single night of sleep deprivation can result in a dramatic increase in your calorie intake overnight. There have been some studies done, for example, in nurses. So there was a study done that followed up nurses for 18 years, and they looked at their weight and how much they slept on a regular basis. And what they found is that those nurses that were sleeping less than about six hours a night on a regular basis, first of all, started off at the beginning of that 18-year period at a slightly higher weight, but over the course of those 18 years, they put on much more weight than other groups. So there is a very clear correlation between sleep duration, sleep quality, and weight gain. We see that, for example, in individuals who we treat with sleep apnea. So one of the treatments for sleep apnea is a mask-like device that you were that stops your airway from closing now and at night. And for some very overweight individuals, actually, when you treat their sleep apnea, they do manage to successfully lose weight where in the past. They found it absolutely impossible to do so. Okay, so if I'm under-slapped, I'm more likely to eat more calories the next day. Yes. Am I also more likely to reach for foods that are high in sugar and bad for me? Certainly, some studies do suggest that. I think it's also important to say that sleep disruption or sleep deprivation has some fundamental effects, for example, on your glucose tolerance, so your insulin resistance, which of course is a particular issue for people with diabetes, but it affects us all. So if you're very sleep deprived, there are changes to the way that not only your appetite or what you're reaching for, but also how your body processes the breakdown of those foodstuffs. Interesting. Because anecdotally, I think I can clearly say that if I'm under-slapped, I'm much more likely to eat something that is high in sugar or. Well, I think we can all testify to that, can't we? I think everybody has known that situation where they're very sleep deprived and they think, "Oh, well, I just need a bit of chocolate." What's going on in the brain, though? Is it something to do with the amygdala and the prefrontal cortex, the emotional centre of our brain and the. Yeah, I don't think we know. I think it's probably to do with the reward mechanisms that underlie our behaviors that there is something about sleep deprivation that alters the rewards that we're seeking, but I don't think I can give you a clear answer on that. You also talked about circadian rhythms. If I was a 10-year-old, what do I need to understand about the circadian rhythm, what it is, what it does, and why it's important? So, within pretty much every cell of our bodies, there is this 24-hour clock. And in fact, if you take a single cell and stick it in a petri dish, about 40% of the genes within that cell will exhibit this 24-hour cycle. And that 24-hour cycle really controls pretty much every biological system within our bodies, be it how our liver works, how our heart works, how our lungs work, there is one particular area of the brain called the super-chismatic nucleus that is viewed as the master clock. It's the clock that coordinates all the other clocks within our bodies. And that influences not only all of these other clocks that are occurring within the cells throughout our bodies, but influences are behaviour as well. So, influences generally speaking when we feel tired and when we want to go to bed and when we wake up. And also influences things like, you know, when we feel most mentally alert, when we want to eat, when we want to drink, when we feel most able to cope with work, for example. Now, that circadian rhythm, that circadian clock, for most people confers the sleep onset of somewhere between 10pm and midnight, if you're an adult, and waking up somewhere between 6 and 8am. Now, the timing of that body clock is governed by two things. It's governed by our genetics. So, whether or not we are genetically predetermined to be slightly later in terms of our body clock or slightly earlier, and we see that in families where lots of people with, for example, will say, well, you know, I've always gone to bed late and woken up late, but so as my father, so as my grandfather, etc, etc. But it's also influenced by what's happening in our environment. About 50% of the definers of our circadian clock are governed by what's going on around us. Be that in terms of when we're exposed to light. So, we know that light is a very important driver of our circadian rhythm when we're eating, when we're exercising, when we're doing a whole range of other activities. And also, one of the markers of our circadian rhythm is the decretion of melatonin. So, there's a very small gland in the centre of our brains, called the pineal gland, which secrete a hormone called melatonin. That hormone tends to start being secreted in most people at around 6 o'clock in the evening. It peaks at the time that we want to go to sleep, and then it's not dropping down a few hours before we wake up. It's almost a chemical marker of our circadian rhythm. But we also know that giving people melatonin in tablet form, for example, can influence our circadian rhythm. So, there's this sort of feedback loop between our own bodies, secretion of melatonin, and what our super-chismatic nucleus, our master clock, is doing. So, by giving people melatonin at particular times of the day, we can shift your circadian rhythm forward or back. So, that master clock in the brain, where is it positioned? The super-chismatic nucleus is in a small area of the brain called the hypothalamus. And is that linked to the eye? There are links from the back of the eye to the hypothalamus. So, there are some cells in the back of the eye, in the retina, that are not involved in vision, not involved in conscious vision, but what they are involved with is detecting blue light in particular, which is the part of the spectrum of light, that is most important in terms of regulating our circadian clock. And there are direct links between these cells that are called red and no ganglion cells and the super-chismatic nucleus. So, exposure to light, to blue light in particular, is really very important in reinforcing or adjusting our circadian rhythm. Now, of course, we live in a world whereby the seasons change, and the amounts of light that we're exposed to changes. So, if we were on a set rhythm all the time that was immovable and un-adjustable, then there would be times where our circadian rhythm might be odds with our environment. So, there does need to be some slight adjustment of that circadian rhythm, and light is probably the most important adjuster. Blue light, is that the light that comes from my smartphone. So, it's so blue light, obviously, the strongest source of blue light is sun. But yes, these kinds of devices, your smartphone, your iPad in front of you, a range of electronic devices also have blue light within them. So, that's why if I'm up on my phone until one a.m. in the morning, staring into the screen, I'm kind of tricking that sort of optic nerve, which is then impacting my master clock, and I'm telling it that it's a different time. Yeah, so the thinking on that has changed a little bit over the last few years. So, you know, it was said that using these devices will trigger insomnia as a result of blue light. Actually, it's likely that the amounts of blue light that these devices put out is probably insufficient to do that directly. But there are two effects of using your gadget until one a.m. The first is on a long-term basis, if you're doing that regularly, it will result in an adjustment of your circadian clock and push it back. So, you will want to go to bed a little bit later and wake up a little bit later, which is fine if you're self-employed or you don't have any restrictions on your time. But most of us need to be up at a certain time in the morning. And if your circadian rhythm is delayed significantly, the net effect of that is that you're going to end up sleep deprived. I mean, there's also the issue of being on Twitter or being in grossed in a movie on Netflix at 1 a.m. that is going to make you delay sleep anyway. So, there are those two effects. It's arousing. It's arousing. And it grips your attention. Well, what do you make of these people? I'm meeping one of them that watch serial killer movies when we fall asleep. Well, I think that that's only an issue if it's stopping you from falling asleep. Do you see it? Because I have this argument a lot with my partner. She can't understand why I need to watch this really stimulating stuff when I fall asleep. She likes quiet. And I need to, I tell myself I need to listen to something. Do you see like variants in this kind of thing, and is there a better approach? This comes down to an individualised approach to sleep, and that's why I'm always very reluctant to say this is the perfect night sleep. These are the rules for sleep. For example, there are some people who for whom caffeine doesn't really influence their sleep and can have a double espresso an hour before bed and still have no problems getting off to sleep. For most of us that's not the case. If you are somebody who can watch something very stimulating, very scary and then switch it off and roll over and go off to sleep, then I guess that's not a problem for you. For most people that's probably not the best thing to be doing at night. I think that long term, one of the issues is with all of these kinds of activities in bed at night before you go off to sleep, is that they weaken the psychological associations between bed and sleep. If you start associating bed being a place where you're mentally active, where you're engaged, then if you have an underlying predisposition to insomnia, for example, then that can sometimes set the stage for developing insomnia later on. The average person that you've treated worked with in your clinical practice that's struggling with sleep is at the heart of the issue, just pour sleep hygiene, because I've got so many friends that say to me that they struggle with their sleep, many of them have struggled with it for years. I doubt there's some genetic reason why this many people are struggling with sleep. Imagine it's just some kind of behavioral reason. I think that the genes that predispose to insomnia are pretty widespread, but obviously in pretty much all areas of medicine, there is an interaction between genetics and environment. And certainly pour sleep hygiene, and that's a horrible term. I hate that term, but it's the term that is most widely used and understood. Concertently putting place certain aspects of behavior that then can give rise to chronic insomnia in the long term. So if you've got very bad chronic insomnia, then suddenly putting good sleep hygiene in place is unlikely to fix it, but it may be that that poor sleep hygiene in the first instance gave rise or at least predisposed you to developing insomnia. And what is poor sleep hygiene? If I wanted to be the worst possible sleeper in the world, what would I have to do? So I think you would probably have to set up your home office in your bedroom. You'd have to have your TV on in your bedroom all the time, have be surrounded by electronic devices, drink a lot of coffee late in the evening, drinks a little bit of alcohol. So alcohol in the short term, of course, is quite sedating. It's a central nervous system, a depressant, but it does dramatically worsen the quality of your sleep and for various reasons, the direct chemical effect. In fact, that you've got a full bladder, the fact that you're probably snoring a little bit more. So alcohol's not a good thing. Not having a wind down period, so gambling on the stock market until 1am, switching your laptop and then trying to go to bed, those kinds of things. So that's the quintessential very, very bad sleep hygiene. What about when I eat? So eating is perhaps less important, but avoiding a very large carbohydrate meal, carbohydrate rich meal before you go to bed for two reasons. One is that we know that it can cause some fluctuation in terms of your blood sugar. And also, if you've got a bit of reflux, it can make that much worse. Okay. What about sleeping in bed with somebody else? Well, I think that for some people, they've, and again, this goes back to no one rule for everybody. You know, if you've got a sleep trait term, sleep reactivity, which is where your sleep is very liable to your environment, then obviously sleeping next to somebody who's snoring loudly or who gets up in the middle of the night two or three times to, to urinate can be, can be very disruptive to your sleep. If you've got very little sleep reactivity, you may actually find it comfortable, more comfortable to sleep with somebody in the same bed as you. I was, I was thinking the other day, because it were, I've currently moved into, there's no blinds or curtains in the bedroom. And I was wondering if that might be a good thing, because it at least means that in terms of my circadian rhythm, I'm waking up at the same time every day, because I'm waking up when the sun comes up. Yeah, but the sun comes up at different times at, at, on different days firstly. So if you were doing that routinely, you might find yourself really rather sleep deprived in the summer months. And also there is some emerging evidence that exposure to light at night in your sleep is not very good for you. So there was a very recent study that implied that light exposure at night increases your risk of diabetes. So it certainly is not good for the quality of your sleep. And the likelihood is that you won't wake up as soon as it's light, you'll wake up an hour or so after it's got light during that hour or so it may have had a negative impact on the quality of your sleep. So having a dark bedroom is really part of good sleep hygiene as it's having a quiet bedroom that is not too hot or too cold. What if you wear a sleep mask? Yes, it does. I mean, I wear a sleep mask. I think it's, you know, particularly if you don't have good blackout curtains or blinds in your bedroom using a sleep mask, particularly in the, in the summer months, is probably very helpful indeed. Does that mean that the only light receptors we have are behind our eyes? Well, I think that there was a, there were some rumors on the internet that there were light receptors elsewhere, but certainly the only ones that we know to be of significance in terms of defining, or circadian rhythm are the ones in our retinas. Because I did psychology when I was in secondary school and I remember reading one of the psychology books, maybe my psychology teacher told me this, I think it was Mrs. Lowney, that there were some studies where they shined a light like underneath someone's knees. Yes. And people would like wake up when they shined their lights there. I think that that's been, very much, discounted now. It is a bit strange though that the only light receptor would be behind the eyes. It just feels like, I don't know, feels like poor design that there's only one place where we figure out if it's night or day. So, so, you know, you see that, for example, in people who've lost their sight. Right. So, so in some individuals who have lost their sight completely, then they lose the regulation of their circadian rhythm and they develop circadian rhythm disorders, something called a non-24-hour rhythm disorder whereby their circadian rhythm is on a, for example, a 25 hour cycle. And so every night they will go to bed one hour later than they did the previous night and will go right the way around the clock, you know, every month or so. So, you know, that's a very good piece of evidence that actually it's those cells in the in the retina that are of crucial importance for maintaining the stability of our circadian rhythm. I wrote that down. I've written in one recent study, 40% of totally blind individuals had a non-24 hour circadian rhythm, which really kind of for me also highlights just how important it is to think about my circadian rhythm and how much impact it's having on my whole body. The other part you mentioned was the biological element to our circadian rhythms, which which people refer to as coronatipes. Yes. And I'll, this idea of coronatipes, which is essentially from my understanding, that genetically we all have a slight sort of disposition to sleep in at certain times. Yes. And to wake up at certain times. Yeah. So there's these names, right? There's like the owl, the lark or whatever else. I think I'm an owl, but that also could just be bad habits. Yeah. So certainly there's that sort of genetic predisposition. There's also these environmental factors, but there's also age in the circadian rhythm changes a little bit as we go through different stages of life. So it's not at all uncommon for teenagers to become more evening of coronatipes. And then as we get older, we tend to shift back to the morning. So that's part and parcel of our aging biology as well. So I think that genetics is really important, but so are other factors as well. Studies and twins suggest that up to 50% of our coronatipes under genetic control. So does that suggest that we are likely to have a similar coronatotype to our family? We are likely to, but obviously our environment is not going to be exactly the same as our parents, or what we do, our behaviours are not going to be identical to our parents or our siblings. So yes, we more frequently see that, for example, people have an evening coronatip that runs in families, but that doesn't mean that we're more than just the destiny of the genes that we hold. Obviously our genes are really important, but so are other factors as well. If someone came to you and they said, "I'm struggling with my sleep." You know, multiple nights in a room, I haven't been able to sleep, I'm getting in bed and nothing's happening and then I'm waking up and I'm just sat there thinking about, you know, sleeping and I feel horrific. Where would you start? So I would start, I think, by trying to understand what it is that is causing their sleep issues, because I. a lot of the individuals that I see who have been referred in with that sort of picture assume that they've got insomnia and they may not always have insomnia. So I think a key issue is that we are really, really poor witnesses to our own sleep. And what I mean by that is that we often are experience of sleep is very different to the reality of sleep. When we bring in people into the sleep laboratory it's not at all unusual and I will almost always ask this question when I'm going through a sleep study with one of my patients is how much sleep do you think you got over the course of that night? And it's not at all unusual for people to say to me, well I think I've got two or three hours sleep occasionally even they say well I didn't sleep at all. And then you look at their brain waves, you look at the best objective marker that you've got of their sleep and you see that they've slept seven and a half eight hours. So obviously what people are experiencing is really important because ultimately from my perspective I want to improve people's experience of their sleep and what it is that they're complaining of. But it's important to understand that what they're telling you may not necessarily be the objective truth. Now that's really important when it comes to insomnia because it's not unusual for me to see individuals who you know they give you a story of very clear insomnia and actually when you look at their sleep objectively you find that although they say they haven't slept at all they've slept seven hours but that seven hours have been completely disrupted by conditions like periodic limb movement disorder which is these leg kicks associated with the rest of the legs syndrome or sleep apnea for example. Now sometimes it's very evident from what people tell you that actually that's not the case that they've just got very clear insomnia. So that's really the starting point to try and decide whether or not you feel confident enough in your clinical evaluation of them that you know what the issue is without doing a sleep study and if you think that they do need a sleep study then that's the point of which we arrange for that. It's also trying to understand some of the factors that might be driving their sleep difficulties. So for example were their sleep difficulties triggered by a life event? Did they have sleep reactivity before this insomnia started? So were they one of those individuals who could sleep anywhere at any time whatever they wanted, whenever they wanted to put their head down or were they kind of individual who the night before an exam before a job interview before a presentation would lose sleep? Because that often is a very strong marker for developing insomnia later on in life. And then it's also about trying to understand how the rest of their health is impacted by their sleep but also how the rest of their health impacts on sleep. So it's not at all unusual for me to see individuals who have been started on medications for other reasons that have generated sleep issues for example. You talked about this sort of obsession with sleep. Hannah's wondering in the case of the patient you've just described would you encourage them to wear a sleep tracker? So first of all I have to say that I'm not ideologically opposed to sleep trackers in general. I think that they are really really good for example in research. Fantastic for research. It allows us to track sleep in very very large numbers of individuals and try and work out how that correlates with whatever we're interested in. One of the major issues with sleep trackers is that the people who often use sleep trackers or individuals who already are concerned about their sleep. So if you know that you're sleeping relatively little and you wake up feeling tired then you probably know you're not sleeping enough. You don't necessarily need a sleep tracker to tell you that. If you're one of these individuals who has insomnia who is spending plenty of time in bed but simply cannot get the amount of sleep that they need. Then what a sleep tracker will do is it will increase your concern, your anxiety around your sleep. It's a very different picture from for example using a step tracker. If you're sitting on the sofa and you look at your step tracker and you realise you've only done whatever it is, 5,000 steps. It's very easy to get up and go for a walk and do another 5,000 steps. If your sleep tracker is telling you you slept really badly and you know you slept really badly and you're already worried about how badly you sleep. It's nothing that you can do on the basis of the information that your sleep tracker is giving you to suddenly go and get a little bit more sleep. And it's complicated by the fact that you know sleep trackers are pretty good at telling you how much time you spent in bed. They're reasonably good at telling you how quickly you dropped off to sleep. The reliability, the accuracy of these devices, most of these devices drops off significantly when it comes to for example defining nighttime awakenings, defining stages of sleep, those kinds of things. So then you have that additional issue in the mix which is that sometimes the sleep tracker may be giving you information that is not factually correct and that may increase your anxiety further. So I'm really very, very keen for people who have issues with their sleep rather than just burning the candle at both ends to put away their sleep tracker and actually go and have a chat with their GP or somebody who knows a little bit about sleep rather than relying on this sleep tracking technology. Do you think sleep trackers have had a negative or positive impact on sleep culture? I think that for those individuals who can fix their sleep in a very straightforward way by spending more time in bed. So the kind of people that I talked about the 20 years ago would be saying well you know I only sleep five hours and you know because I'm busy doing X, Y and Z and I can get away with it. I think it's probably encouraged them to spend a bit more time in bed because they know they have a very clear, very clear bit of information that's telling them they're not sleeping enough. But for the people that I see, the people who are already concerned about their sleep and who have difficulties with their sleep, I think it's been a very negative impact. And I have some reservations about well people like myself sitting on these kinds of podcasts or writing in newspapers telling you well you know if you don't get enough sleep you're going to die early, you're going to have all these negative health consequences because for a subgroup of individuals who are already very concerned about their sleep that actually can cause problems. And I have seen individuals who for example have read books on sleep and how important it is on sleep who have ended up going into a spiral of insomnia and very catastrophic depression and anxiety as a result. So it's very important to be clear that all of this is a double-edged sword. It's interesting with sleep trackers. I can see I think it's worth me saying that I am both an investor in WIP and I'm also sponsored by WIP but I also agree with the things you've said. So I've seen this sort of variance in how a sleep tracker can improve some people's lives and it can make other people more anxious in a way that's not helpful. So for me my sort of testimony on it is I was one of those people you described earlier that thought sleep was take it or leave it. And when I started seeing a sleep track it's kind of like when I saw my brain for the first time I did a brain scan and I didn't even kind of like realize it was there and I could influence it and that things I was doing without really thinking much were having this big impact and for me what it did is it allowed me to finally make this link between how much sleep I've had and then how I behave. Now I thought my behavior was random but seeing that when my sleep scores were down I was way more emotional. I was way more likely to eat crap and the other thing that I saw which was really interesting was that when I had a glass of wine or two glasses of wine, three glasses of wine that it just like destroyed my sleep and I never knew that before and I was in search of reasons to quit alcohol anyway and when I saw that I quit alcohol forever so I've not drank since. So and then for me I have to also say there are moments in my life where life happens and I know I'm not going to sleep and I don't pay attention to my sleep tracker but there are other moments where I have a bit more control and that's when I kind of tune into my sleep tracker I've also had parents message me a lot and say listen I've got a one year older, two year older, three year old, whatever there's no point me wearing a sleep tracker because listen I'm not going to get any sleep and I also completely agree with them that there's really no point in that situation. I think there's a point when there's something you can do about it. Yeah that's absolutely key. So the point of doing anything like that is if there are very clear things that you can do on your own to close that leap there's no point having information without being able to act upon it. Yeah. And I guess if you are one of those individuals like yourself who very clearly can correlate certain things that they're doing in their daytime lives with their sleep and and how they feel subsequently then then great. You know I guess I have a little bit of bias in that the people that I see are already struggling with their sleep already and so it goes but I guess we're completely in agreement. Yeah we are yeah. And it's so interesting because I that's been a developing idea because obviously my bias is always like wouldn't you rather know because that's you know but then from doing this podcast I've seen the comments and I've seen the struggle in from speaking to parents that struggling with their sleep and it's kind of sometimes just makes them feel worse about it. I think nuance is necessary on this issue and I'm sure there's a lot a lot of things in my life that I wouldn't like to try to do. be able to track because either I don't have control of them right now or maybe they'd make me feel more anxious. There's this thing called the glimphatic system, which I find really, which when I discovered this, it really helped me to understand the importance of sleep. Can you explain what the glimphatic system is as if I was a ten-year-old? Yeah, so within our bodies, there is a system, a very similar system called the lymphatic system, so people will have heard of lymph nodes, for example. And this is a system whereby fluid that comes out of the blood vessels and into the tissues is then collected and transported back into the cardiovascular system. And we used to think that there was no equivalent system in the brain, but actually, over the last 20 years, we've understood that what's there are no lymph nodes or things like that, there are these very small channels between the cells that are responsible for draining fluid from the brain. And those systems are responsible for removing certain toxins or metabolites, chemicals that have built up as a result of metabolic activity within the brain and removing them from the brain substance itself. Now, it's like a carwash. Like a drainage system, like a gutter, for example, that takes the suds from the carwash away and puts them into the drain. In about 2011, if my memory serves me correct, there were some studies done that looked at that glimphatic system in different stages of sleep. And what they described was that that glimphatic system opens up significantly by about 60% in very deep sleep, in the deepest stages of sleep. And so subsequent research showed that, for example, one of the proteins that was being removed was a protein called B-tramloid, that is intimately tied to Alzheimer's disease. And so the view that deep sleep was particularly resp… Granger knows, when you're a procurement manager for an office park, you're not managing one building. You're managing all of them. And to stay ahead, you need to see through walls and around corners. Lights about to fail, filters ready to clog, H back on its last leg. If you wait until something breaks, you're already behind. Count on Granger, for quality products, easy reordering and 24/7 support. Call 1-800-GRanger, click Granger.com or just stop by. Granger, for the ones who get it done. Sponsible for housekeeping of the brain for chemical housekeeping of the brain came about. It gets a bit more complicated because only a two or three weeks ago, another study suggested that 60% increase in the glimphatic system was not the case. And so I think that this remains an area that there is some uncertainty about. But actually, there are many reasons to tie in sleep in general, separate from the glimphatic system into a general housekeeping role of the brain. And I think that certainly this is an area that is going to keep researchers very, very busy over the next 10 or 20 years. This association between sleep, cognition and cognitive decline in later life. That protein that seems to spike if we are sleep deprived. Beta amyloid? Beta amyloid, yeah. And that's linked to Alzheimer's. It is, yeah. In Alzheimer's disease, we see beta amyloid deposition within the brain substance itself. What is deposition me? So it's deposited within the brain. If someone has Alzheimer's, they have a sort of these build up of beta amyloid in the brain substance. Is there a link between sleep deprivation and Alzheimer's? Do we see high numbers? So there is some evidence to suggest that both chronic sleep deprivation and insomnia are associated with cognitive decline and conditions like dementia. It goes back to what I was saying earlier, which is, by the way, there's also some studies that have suggested links between sleeping tablets and conditions like Alzheimer's. So it goes back to this issue of whether or not it's the insomnia or the sleep deprivation that causes Alzheimer's. Is it sleeping tablets that causes Alzheimer's? Or is it the fact that Alzheimer's many, many years before causes changes to our sleep? And so I think that that story has not yet come to fruition in terms of our fundamental understanding of the links between sleep and Alzheimer's disease and whether or not it's directly causative. Do you recommend slash are you a fan of you preferent sleep tablets, sleep medicine medication? Yeah. So as a general know, because I think that there are good, now non-drug based techniques for trying to improve sleep in the majority of people with insomnia. There is some evidence that for example, if people don't respond to these non-drug based methods, giving them sleeping tablets alongside these non-drug based methods makes it more likely for the psychological route to help. But unfortunately as part of my clinical practice, I see lots of people who have been struggling with it asleep for many, many years and they've tried all non-drug based treatments. And the risks of them sleeping so little in terms of their mood, their anxiety, their ability to function are so great that actually you have on a case by case basis to make a judgment call as to whether or not to say, well, I give up on your sleep or actually you say, well, look, there are a number of drugs that we can try to try and improve your sleep and it's not going to get you back to normal, but it's going to potentially make the difference between you end up very depressed or highly anxious and unable to cope in your life or actually get some decent sleep. And the risks of those drugs and that needs to be judged on a case by case basis and it's part of clinical medicine. Whenever we prescribe any medication for anybody for any condition, we have to evaluate what the potential benefits are versus the potential risks. A lot of people seem to be taking melatonin tablets. Is that healthy? Is that free from side effects? So it's not entirely free of side effects, but it's generally a pretty well-tolerated safe drug as far as we know. There are some specific issues surrounding melatonin, but a question really would have to be, well, why are you taking that melatonin? There's something that you can do to fix your sleep without relying on an exogenous substance, something that you've brought off the shelf or been prescribed. Is my hesitation and reservation with taking things like melatonin is always that I just assume that my body will become a little bit reliant on it? Yeah, well, I think whether you become physiologically, biologically reliant upon it or psychologically reliant upon it remains unanswered. But certainly that there are individuals who, for example, say, well, as long as I know that I've got a bottle of melatonin or the sleeping tablets in my bedside cabinet, I sleep fine. As soon as I know that I haven't got access to them, I don't sleep very well at all. And so that, I think, exhibits that this is almost like a psychological crutch, knowing something that they've got next to their bed that they can reach for in order to achieve a good night's sleep is sometimes as important as the biological effects of taking that tablet. I mean, that kind of leads to the non-medical techniques to improve our sleep. So you said typically with someone that comes to your sleep center, instead of going straight to medication as the answer to their sleep issues, you would suggest and/or try non-medical interventions. Yes. And you said that these work well. Yes. What are these non-medical interventions? So the gold standard treatment now for insomnia is a treatment called cognitive behavioral therapy for insomnia. Okay. So a lot of people have heard of CBT because they will have heard of it in the context of depression and treatment of a depression or anxiety. Now CBT for insomnia is not actually directly related to the CBT that's used for depression and anxiety. It borrows from the principles of CBT and applies them to sleep. And it serves two purposes. The first is to try and address some of those conscious psychological factors that are driving insomnia. And when I talk about conscious factors, I'm talking about things like the frustration or anxiety of the night ahead of lying in bed at night feeling that you can't get off to sleep and the frustration and anxiety that that engenders of having your partner snoring away in bed next to you whilst you're struggling to go off to sleep, of worrying about how you're going to be able to function the following day or potentially even the long term effects of your insomnia. So those are the conscious psychological factors and CBT aims to address those, but it also aims to restore normal unconscious factors that give rise to good sleep. So if you've spent a great deal of time in bed at night awake, then those normalist associations that good sleepers have between bed and sleep. So for a good sleeper, they will associate bed with being a place of comfort, with being a calming, relaxing place, a place that they associate with a good night's sleep. If your sleep has been disrupted for a period of time, and you've spent long periods of time in bed awake, then that positive association between bed and sleep is replaced by negative association. So you begin on a unconscious basis, a havelovian conditioning is called, you associate that bed environment with being awake, with being wired, and that's often what gives rise to this sensation of having lost the switch to be able to get off to sleep. In fact, some people within somebody will say, well look, you know, if I'm sitting in front of the television and I'm sitting on the sofa, and I'm not thinking about sleep at all, I'm not thinking about bed, I will often find that I've dosed off, and then I'll go upstairs, get into bed, and as soon as my head hits a pillow, ping, I'm wide awake and I suddenly feel wired. So that's very illustrative of that sort of unconscious association between bed and being awake, or rather being asleep, and so CBTR aims to address that as well. - How does it do that? - So it uses a variety of different techniques. So it uses some standard sort of relaxation techniques to try and reduce the level of vigilance, of physiological, of mental arousal that you have when you get off to bed, but also it aims to utilize a variety of techniques to reprogram your brain to associate bed with sleep. So one of the ways in which you can do that is you can actually utilize your brain's own mechanisms that drive you to go off to sleep. So that's something called the homostatic mechanism, which will all be very familiar with, but not in those terms. So the more you've been awake, the stronger the chemical drive for your brain to go off to sleep. So one of the features of CBTR is to compress your sleep or to restrict your sleep for a period of time. Essentially what that means is, well if you are an in somebody within Somalia, and you estimate, for example, that you're only sleeping a total of six hours of night in bed, but you're spending eight hours of night in bed, then you, for a period of time, you say, well, look, I want you to get into bed at midnight and whatever happens, I want you to get out of bed at 6am. So to restrict the time in bed to six hours. So the first few nights, most people within Somalia will sleep really badly 'cause they know that their alarm is going off at six and they know they have to get out of bed at six. But after a little while, they become so sleep deprived that the brain starts forcing you to go off to sleep much more quickly. And over time, more and more of that six hours of night will be spent asleep in bed. And that's the first step in breaking that negative association between bed and wake and rebuilding a positive association between bed and sleep. I mean, at its extreme, there is a technique that was developed in Australia, which is called intensive sleep retraining. And in that technique, people who've got very bad in Somalia, are brought into sleep laboratory having been awake for the night before they come in. So they come in in the evening, having been awake for now probably 36 hours. Every half an hour, they're given the opportunity to drop off to sleep. They have some wires on their heads, their brainwaves are being tracked. But as soon as they've been asleep for three minutes based on their brainwaves, they're woken up again. And that happens every half hour for 25 hours. So over the course of that 25 hour period, they have 50 opportunities to nap. Now, for most people within Somalia, having been awake, even having been awake the previous 36 hours, they will still not be able to get off to sleep for the first few naps. But as they get more and more sleep deprived, every time they're given the opportunity to drop off to sleep, they will start falling asleep more quickly. And at the end of that 50 naps, they will be dropping off to sleep very quickly as soon as the lights go off. And actually, the evidence suggests that that's a very good short-term treatment for chronic insomnia. And in some individuals, it works extremely well in re-associating your head hitting the pillow with drifting off to sleep. I wouldn't suggest it for most people 'cause it's basically a form of torture. But I think it illustrates the power of trying to get people into a more sleep deprived state if they've got insomnia. - It's interesting 'cause much of what you've said makes me think that we all have our own sleep identity. And when I say sleep identity, I mean, a story we tell ourselves about our relationship with sleep. And it makes me think that our sleep identity is much more powerful than I think we think. 'Cause if you speak to anybody, anybody in this room upstairs, wherever, and you say, "What do you like at sleeping?" They will deliver their sleep identity. They'll say, "I'm a bad sleeper." And I wonder how much of that is self-fulfilling. 'Cause I think I've always told myself that I'm a good sleeper, and therefore I find sleep easy. And I've got friends who will say, "Oh, I'm a really bad sleeper." And I'm wondering how much that's impacting their ability to sleep and/or if they even know objectively if they are actually a good or bad sleeper. It's just this identity we've embodied. Do you see that a lot? Do you see that someone's sleep identity kind of determines how they actually sleep? - I think all of that is true undoubtedly. And I think this comes back to the earlier bit of our conversation about sleep trackers because obviously sleep trackers reinforce that sleep identity, whether they are 100% accurate or not. And so yes, that sort of sleep identity would undoubtedly influence both those conscious and unconscious factors that give rise to sleep. You know, if you're a good sleeper and you've always been a good sleeper, you don't worry about any of these things. You probably don't even worry about any aspects of sleep hygiene. I'm quite happily, you know, like you watch a horror movie in bed before you drift off to sleep. But for those individuals who are not, yes, absolutely that, the way that you view sleep and your relationship with sleep is of fundamental importance. It is, again, coming back to genes, we know that there are undoubtedly genetic factors that influence whether or not you're likely to develop insomnia. So again, as with all aspects of sleep, it's that combination of genetics environment. And when I talk about environment, I'm also talking about your own psychological internal environment. I am, the other thing I was thinking, we talked about sleep happening earlier on, but it seems that a lot of people believe they have a deviated septum. Is it called deviated septum? Septum, yeah. Septum, yeah. Septum. I've heard some people say that that's the reason that they can't sleep. And they've gone off to get surgery to kind of correct the deviated septum. What's your thoughts on that? Is that true? Because I wonder how I'm like, do you, we can't all be being born broken with these deviated septums or whatever? I think it's normal for us to have some asymmetry in our noses. And a lot of people have a deviated septum, septum as a result of having broken their nose, for example. You know, I'm a little bit suspicious about, you know, operations for that kind of thing. Unless there are very clear abnormalities that might be responsible for sleeping poorly. So one of the major issues, for example, in sleep amniaries, sleep amni, the obstruction is in the throat, it's not in the nose. And so issues with nasal congestion or difficulty breathing through the nose do not directly cause obstructive sleep amni. What they can do in some individuals is they can encourage them to people to breathe through their mouth and breathe with their mouths open, which alters the position of the jaw and can create a bit more narrowing in the back of the throat. So for some individuals who have very prominent nasal congestion at night and who have evidence of sleep amni, sorting out their nasal congestion and correcting a deviated septum maybe one way of doing that, there is undoubtedly irrational for sorting that out. I think that there are probably quite a few individuals who are having unnecessary operations. - Makes sense. - So we've got the cognitive behavioral therapy for insomnia as one cure. We've got that extreme torch therapy that they did in Australia. We've got melatonin, magnesium, people have mentioned magnesium. - So anecdotally magnesium can help some individuals. And anecdotally also magnesium is a very good treatment as testified to by some of my patients for conditions like restless leg syndrome. - So restless leg syndrome is this sort of neurological disorder whereby people, and it's often associated with things like pregnancy or low-on levels but it's under genetic control as well. People experience a number of different things. So the first thing is that they get an urge to move at night and it's typically at night rather than during the day often associated with unpleasant sensations that if they try and keep still that sensation builds and builds until they have to move. That if they do move they get some transient relief and it's often associated with kicking at night in your sleep. It's very common, very common in pregnancy, very common in people who are anemic and in people who've got problems with their kidneys but it's common in the general population as well. And so for people with restless legs syndrome, magnesium does sometimes help significantly. And it was it. is relaxing as well. I don't think we actually know precisely what it's doing. When you look at an under-slapped brain, so if I was sleep deprived, what would the difference in my regular sleep activity be? What would you see? Would you see my brain as not active? Would you see part of it not active? We would see on a gross level, on a sort of macro level, we would see that your brain is prioritising very deep sleep over other stages of sleep at night. On during the day, if you were chronically sleep deprived using the techniques that we use in clinical practice, you would see very little. There is some increasing evidence that actually what is happening within our brains is that we are constantly showing little areas of our cerebral cortex, the outer lining of our brain, the bit of the brain that's responsible for our cognitive abilities, for example, that dip it in and out of electrical silence, what has been termed local sleep, so that there are little islands of local sleep that are constantly occurring over our cerebral cortex, what's to wear awake. As we get more and more sleep deprived, and depending on how much we've used that particular bit of our brain, those islands tend to get slightly longer, the periods of silence get longer, and those islands become more widespread. We're constantly, even with you and I are talking, there are little areas of our brain that are constantly dipping in and out of sleep. If we're very sleep deprived, actually that electrical silence of our cerebral cortex gets more extensive and more widespread, which is probably why, or at least one of the reasons why we decline from a cognitive perspective when we are very sleep deprived. Okay, so my, okay, interesting, because okay, so different little parts of my brain are doing little micro-sleeps if I'm sleep deprived. And that, from a behavioral standpoint, will show up in my day-to-day life as worse cognitive performance, maybe less focus. Because I've always wondered why on an un-slept day, I feel like I'm more emotional. People say they're a test of the fact that if someone's a little bit cranky, they think "Oh, they probably have not slept last night." There's that phrase and they're like, "Who woke up on the wrong side of the bed?" etc. Is there a scientific basis for that? So I don't think we can fully explain it. I think that there are certainly the areas of the brain that are responsible for emotion and emotional cognition are more metabolically active and so maybe more vulnerable to the effects of sleep deprivation. I think it is likely that when you're sleep deprived, there are some changes in terms of certain neurotransmitters within the brain that may exacerbate that. But what's very, very clear is that that association between sleep, mood, anxiety levels is very, very clear. And in fact, we see that, for example, in people with clinically significant anxiety or clinically significant depression that actually treating anxiety or depression in somebody who is sleep deprived or has insomnia as much more difficult, that treating the insomnia where in somebody who is anxious or depressed is much more difficult without addressing the anxiety and depression. And so this is really significant, not just on a day-to-day basis for all of us, but also in clinical medicine and clinical psychiatry. So jumping back to the point about when we're under slept certain parts of our brain are doing little micro-sleeps, it is fair to say that the phrase that we're half asleep, there's some merit to that. Yeah, we may not be half asleep, but we could be a thousandth of sleep or a hundredth of sleep. And this idea that the brain can exist in different stages of sleep or wake at the same time, by the way, also extends to the night time. So for example, in people who sleepwalk, who do really rather dramatic things, and I've seen patients, for example, who've driven in their sleep, one patient who rode a motorbike in their sleep. I've seen people do some incredibly complicated things like cooking a meal in their sleep. All of these sleepwalking type events relate to the fact that certain parts of the brain are in very deep sleep, whereas other parts of the brain actually demonstrate waking activity. So the bits of the brain that are remain asleep are the frontal lobes, which are basically where our rational thinking, where our decision-making occurs, and the parts of the brain that are responsible for memory are part of the brain called hippocampus. Whereas actually in these events, there are other areas of the brain like the areas responsible for movement or vision or emotion demonstrate waking activity, both on an electrical basis, but also on a metabolic basis as well. Why do we dream? It's a big question, isn't it? It's such a big question. The short answer is, I think we still don't know. I think there are lots and lots of theories about why we dream that those range from dreaming sleep being fundamental for reinforcing memories, for regulation of our emotional memories. And I think you've had Matthew Orcoran previously who probably talked about this view that dreaming sleep is emotional rehabilitation, form of emotional therapy. One of the unanswered questions is, for example, why when we are born or when we're in our mother's womb, we spend the third of our lives in REM sleep. And yet, and that drops off significantly as we get older, to the point where by the time we are elderly, we're doing very little REM sleep at all overnight. So this kind of rapid decline in the proportion and the amount of REM sleep that we are exhibiting has been explained by some individuals as it being fundamental to the development of consciousness, for example. So there's a chap called Hobson, who is based in one of the Ivy League colleges in the States, who was very keen on this idea that REM sleep is part of the early development of consciousness as we are inside our mother's womb and may be fundamental subsequently to learning new things, to learning new motor tasks. The honest answer is I think that there's probably more than one function, in fact, many functions of REM sleep. So REM sleep is the stage of sleep where we start to dream, right? So REM sleep is the stage of sleep that we most associate with dreaming, and it's the stage of sleep that is most associated with dreams of a narrative structure, so these kind of stories that evolve, that have a plot. But actually we know that lots of people dream in non-REM sleep as well, and then you can see that in, for example, people who sleep walk or have night terrors, they will often very clearly be able to remember dreams, but those events will have arisen from very deep non-REM sleep. So we do dream in other stages as well. It feels like it's not a great evolutionary trait to have nightmares. I can't understand the basis of having a nightmare and why that's a good thing. You know, I'm not sure that that we're evolutionally driven to have nightmares. I think that what nightmares represent is the fact that we've had these kind of mental experiences, but we've woken up to the extent that that nightmare has never been completed, because usually we forget our dreams. We almost all of us go through four or five cycles of REM sleep a night, and so we're probably having dreams throughout the night, but most of us don't remember the vast majority of our dreams. We remember the dreams whereby we've woken directly out of REM sleep. Why is that? Why do we remember the dream when we wake up? I think that's another unanswered question, but it's quite clear that that rapid transition between REM sleep and wake means that the memory of whatever it is that we've been experiencing has not been fully cleansed, has not been removed. Now that goes back to Matthew Walker's theory of REM of dreaming as an emotional therapy, because the argument is that if you've experienced something that is so strongly driven by emotion, you've had a very traumatic experience. One of the reasons why you don't recover from that is because when you're dreaming about that event, you will invariably wake up because the emotional content of that dream is so high, which is why these kind of recurrent nightmares are part and parcel of post-traumatic stress disorder. You're never completing that process and you're never allowing yourself to achieve emotional recovery from that original trauma. So one could argue under the theory that our dreams are therapy that it's our subconscious mind playing through the scenario in order to maybe better understand it and process it and to come to peace with what happened, maybe learn from it. You know, from an evolutionary perspective, okay? So if you've had a traumatic event, say you were attacked by a lion out in the wild, then obviously having a very, very strong emotional association with the terror of being attacked by a lion is very important for you to avoid that again and to learn from that event. But what you don't want is you don't want the next time you see that lion to have such an strong emotional response to it that you can't do anything about it, that you freeze. because that's not very good for your survival. So you want to learn from these very strong emotional events, but you don't want that emotion to be heightened to the same extent that it was during that original experience. So from an evolutionary perspective, there is some rationale to that. What's the most upsetting case of a sleep disorder that you've ever seen? I mean, I've seen a lot of very upsetting cases, you know, I've seen individuals who have committed crimes in their sleep. Really? Yeah. I kind of crimes. So I was involved with somebody who not in the UK, I would stress, who shot a family member in their sleep. I've seen individuals who have committed sexual assault in their sleep. But also, there's a rape. Yes, somebody who was convicted for rape as a result of a sleep disorder. Now, obviously, you know, one of the great difficulties is that you can never be absolutely sure whether during that particular episode, they were in their, that that occurred during their sleep disorder, but what you can certainly say with a degree of certainty is that there is clear evidence that they have exhibited similar things that have definitively occurred out of their sleep. But also some of the effects of these sleep disorders on people's lives is really dramatic. So I look after a large number of individuals with a condition called Cline Levin syndrome, which is a very poorly understood condition, often affects young kids and teenagers. And they will go through, there'll be fairly normal between episodes. And then during episodes, they will be profoundly sleepy, sometimes sleeping 23, 24 hours a day, when they're awake, they're very confused, they exhibit very abnormal behaviour, eating behaviour, sexual behaviour. And that can last four days or weeks out of the blue, which can have a massive impact on people's education, people's social lives, you know, how they're managing in the workplace. So these sorts of conditions can devastate people's lives. In the case of the person that killed somebody while they were asleep, did they get convicted of that crime? That is still in process, as I said, it's not in the UK, which is what I'm mentioning it. But you know, there have been many examples of individuals who have who have been found not guilty as a result of a crime, including murder, having occurred in their sleep. Now, as I said, there is always a degree of uncertainty as to whether or not a particular event happened in sleep. But what in those individuals we can say is that there are many individuals who exhibit similar sorts of patterns of behaviour that have been clearly demonstrated to arise from sleep. What do you have to demonstrate in order to. When that goes to court, what are they looking at? Are they looking at your past sleep behaviour? Do they put you in a sleep laboratory and check? I think both of those things. So, you know, first of all, is past behaviour consistent with what has happened on that night in question? Secondly, are there any features about the event itself that suggests that there was an attempt to, for example, cover it up or a degree of pre-planning in order to commit that particular act? And also whether or not there can be evidence found by studying that individual sleep that they suffer from these kinds of sleep disorders? I read about the famous example of Kenneth Parks, which is pretty unimaginable. Yes. What is the story of Kenneth Parks? So Kenneth Parks was a chap who was based in Ontario, who apparently in his sleep drove several miles to his parents in law's house. 23 kilometres. Long, long way and apparently got a tyre iron out of the boot of his car, bloodied his mother-in-law to death and then tried to kill his father-in-law and ended up throwing him into a swimming pool. Now, this was made even more curious by the fact that there had been some evidence that he'd been having some financial difficulties and had had some discussions with his parents in law about financial issues. But it was deemed by a court of law that this happened whilst he was sleepwalking and he was actually acquitted. So this is a remarkable story. Now, is it impossible for somebody to drive in their sleep? No, I've seen it myself. It seems stretching credibility that somebody could have undertaken all of that whilst sleeping, but in the court of law he was found not guilty. That's crazy. Have you ever seen someone drive miles in their sleep? Yes, I've got a patient who I don't see any more, who I mentioned in my book, who has driven several miles in her sleep and in fact has driven a motorbike in her youth in her sleep. And the only knowledge that she had was her landlady at the time, said, "Where were you going at one o'clock in the morning clutching your motorcycle helmet?" And she'd obviously been for a ride in the middle of the night without any recollection. I think this goes back to what we were talking about, which is, are we half asleep or we're 100th asleep or we're 1000s asleep? So in those kinds of situations, it's likely that actually the majority of the brain is probably awake because it's very hard to envisage how somebody may be able to do something quite so complicated when the majority of the brain is asleep. But crucially, the parts of the brain that remain asleep are the bits that are responsible for rational thinking. I mean, why would she have gone for a motorcycle ride in the middle of the night if she was thinking rationally and also the bits of the brain that are responsible for memory? What proportion of people that are, because there's various types of insomnia isn't there, there's not just one type of insomnia. I read about this sort of short sleep duration insomnia. And then in other insomnia acts where they might be in bed for eight hours and sleep for hours, but they're not getting sufficient restorative sleep. Is that it? So we know that, going back to what I was saying about us being poor witnesses to our sleep, the majority of individuals who have insomnia, subjective insomnia, when you bring them into a sleep lab, they may be sleeping slightly shorter than normal based upon tracking of their brain waves, but probably don't sleep a huge amount less than normal individuals. It's their subjective experience of sleep that is impacted rather than the true duration of their sleep. Those make up the majority of individuals within insomnia, but there is a subgroup of individuals who say, well, you know, I sleep four hours a night or three hours a night and they really do only sleep two or three hours a night. Now in those individuals who kind of have the feeling that they are sleeping very little, what we are actually beginning to understand is that there are some again, some local changes in the way that the brain acts, so that there are areas of the brain, for example, that might be responsible for awareness that don't switch off to the same extent at the rest of the brain. So whilst the majority of the brain may be sleeping, those little areas of the brain that are responsible for our awareness at night for what's going on in our environment may not be switching off to quite the same extent. And so there's a sort of huge spectrum of what insomnia actually is. What hope would you offer insomniac? Because you know, this video is going to draw in a lot of insomniac. It always does whenever we talk about sleeps, when I look at the comments and the feedback and the reviews, etc. And it seems that insomniacs converge here looking for answers. So I would say that the odds are in your favour that there are some very effective treatments for insomnia, that it's not always straightforward because insomnia interacts with a whole range of other conditions that may be affecting you, like your mood, like your anxiety levels, like what's happened in your past. And sometimes it requires a multi-pronged approach, but for the majority of individuals we can make sleep better. You know, one of the real big issues that a lot of people are seeking for rapid or instant answers to their insomnia, which is why a lot of people end up on drugs. That may not necessarily be the right approach for you. And I would really countenance that, you know, the treatment of an insomnia can in some individuals take some time. And it's important to have a degree of patience to try and fix this in the long term rather than to provide a short-term solution. What's what a percentage of insomnia actually think recover? Well, I think that if you extrapolate on the basis of CBT, CBT-based approaches, we know that helps about 80% of individuals. Really? 80%? Yeah, up to. And, you know, that these drugs do help some individuals, as I, you know, I would stipulate again, I would stress that, you know, drugs are need to be used to caution. sleep in the right individuals. So, you know, I said the odds are in your favor. You wrote this book called, you know, The Secret World of Sleep, which is a real pioneering book on the subject of sleep. But I also have this other book in front of me called The Man Who Tasted Words. And at the bottom of this book it says it's a fascinating, important and disturbing book. All of your work seems to center on the weird way that the brain operates in its patterns and how that impacts our everyday lives. But The Man Who Tasted Words. Why did you call the book The Man Who Tasted Words? So, one of the individuals in that book is an individual who is not a patient, who doesn't have anything wrong with him. He's got a condition called synesthesia, which is the melding, the combining of certain senses. So, when he sees objects or hears objects, he gets a taste associated with them. So, he gives a really good example of his, you know, in childhood his friend had a girlfriend whose particular name in him gave him a awful taste. And every time his friend mentioned this girl's name, his mouth was filled with a terrible taste. So, he will read words, he will hear words, and all of those words will be associated with a particular taste that has lasted his entire life and it's been very fixed. So, as a kid, when he started reading, he learned how to read by looking at the tube map on the way to school. And each of those tube stations has got a particular taste associated with it and that taste has remained fixed throughout his life. Now, this sounds really very strange, but actually we know that some degree of synesthesia, some degree of melding of our senses is actually quite common that up to about 4% of individuals exhibit some form of synesthesia. And it really, I think, illustrates how in all of us, our minds and our brains and our nervous systems work in slightly different ways to define our reality. And it's an exploration of how our nervous system can influence how we perceive reality to be and that truth may not always be what we perceive. There's another patient in that, not a patient, another woman in that book who has synesthesia, she's a musician and when she plays music, she will see colours washing in and out of a vision. And so for her, every time she hears a piece of music, that will be accompanied by a visual phenomenon, sometimes even a sensory phenomenon. So certain pieces of music or certain sounds will precipitate certain sensory experiences. I've often heard, you know, hear about rainman and various types of autism where these sort of apparent geniuses say that they see, what do they say? They say they do maths with like shapes in their brain. If you ask them what four plus four is, they describe that it kind of appears in front of them as a shape. Yes. So that is a form of synesthesia and we know that synesthesia is much more common in people with autistic spectrum disorder than it is in individuals without neurodevelopmental disorders. What does this tell us about the nature of our experience? For someone that's not living with synesthesia, does it mean that there is no such thing as truth? I think what it tells us is that our reality, what we perceive truth to be, is intimately linked with the structure and the function of our brain. And whilst we all assume that people's experiences of the world, and by the way, the way that we interpret those experiences of the world are all identical, that is very far from the truth. And I think it gives us some insight given the fact that how we perceive reality even in the context of an entirely normal and entirely functioning nervous system is so predicated upon our experiences, is so predicated on our model of the world, that you know the brain works as a prediction system. So it works by assessing whether or not what our senses are telling us or in keeping with what our expectation of the world is. So we need a model of the world as we understand it. And that model of the world is influenced by our experiences, by our genes, by the structure and function of our brain. So it's not necessarily surprising, given that we all have very different experiences in life, that we have different genes, that we will have gone through different things, that our truth may be very different from the truth of others. And that our experiences, our perceptions of the reality of the world may be very different. It kind of explains why there's a lot of polarization and a lot of conflict to some degree. I think it does. I think you only need to have a look on Twitter to see how differently different people perceive exactly the same situation. But also one might argue that if there's people who have entirely different perceptions of the world because of their brain and their nervous system that maybe they're not guilty of crimes that they've committed. Well, I think that's the subject of the third book. Yeah, Seven Deadly Sins, the biology of being human. I had this debate with my friend the other day because I was reading about some studies. I think it was a study that showed a guy with a brain tumor had gone out and suddenly he was like a normal teacher and he'd gone out and committed some horrific, horrific crimes. And when they removed the brain tumor from his head, he stopped committing all these crimes. And so the question becomes like, is this person to blame for these crimes? But then you could obviously stretch that out further and just go, when people are serial killers oftentimes, we find that there's something in their brain or there's some early trauma or there's some neurological issue that they've had. So are they guilty? Well, indeed. And that's a really important question, which is how much free will do all of us have if we are all essentially machines that are doing the bidding of our brains than anything that affects our brain function defines our behaviour. And the book that is out in November very much discusses the neurological and psychological conditions that can influence our behaviour in really rather dramatic ways. Be that from the perspective of gluttony or wrath or pride or any of the other seven deadly sins. Why did you write this book? This book seven deadly sins. Because it again reflects some of micro-neutral practice that I see individuals who have brain conditions that dramatically influence their behaviour. Now the question in always in my mind is, well, firstly, does this reflect their own morality and it's quite clear that in those individuals it doesn't. But what are the implications for all of us? And as you already said, if that is the case for, if a brain tumor can suddenly cause a dramatic change in behaviour, if a stroke can, if Parkinson's disease can, if a chemical change and some of the people that I detail in the book are individuals who are very similar to patients in mind in whom I've started an anti-aplectic drug, for example, exhibit a dramatic change in their behaviour. And so a simple chemical taken tablet form can result in those changes of behaviour. What about all of us? Are there things in our environment? Are there things that we are doing that influence the machinations of our brains? So do these kinds of behaviours then take a moral viewpoint or should we be looking at them from a biological perspective rather than a moral one? Give me one such extreme behaviour where you've seen some kind of chemical intervention or other intervention completely eradicate that behaviour. So I've certainly seen a lot of individuals, so I said at the start that one of the specialist clinics I do is an epilepsy clinic. And there are anti-aplectic drugs that are well known in a very small proportion of individuals to cause a dramatic increase in irritability, anger and aggression. And I remember one of the earliest patients that I saw started on this drug was a very frail little old lady who must have been in her 70s and who was arrested by six police officers in her front garden being pinned down because she was so violent and aggressive. So that's one example. Lots of patients who, for example, exhibit behavioural change after a seizure. I've seen individuals who have had autoimmune conditions of their brain who have become frankly psychotic, you know, ripping sinks off the wall in their hospital room, trashing their hospital room, attacking their nurses who actually, when that condition is treated, they've reverted to normality. And in the case of the very angry grandmother who was kicking off the police, was she cured of that behaviour? The drug was stopped and she returned to normal. The drug was stopped? Yes. So it was it took her off the anti-aplectic drug. replaced it with another and she normalized. Of all the extreme cases you've seen throughout your work and through these books you've written about sleep and the seven deadly sins and the man who tasted words, what is the most surprising crazy story that you've encountered that that showed just how extreme and bizarre the human brain can be? So I think probably the one that sits with me in the most emotional way is probably a young man that I met who has never been able to feel pain throughout his entire life from the moment that you have born and in fact he has a genetic disorder that was also inherited by two of his siblings and none of the three children have ever been able to experience pain. Now at first glance you kind of think that might be quite nice never to experience pain but meeting somebody like that and you realise quite how important pain is for our normal development for our normal lives. He tells stories of him and his sisters essentially holding their hands up to the far to hear the sizzling of their hands because they thought it was funny they didn't feel any pain. They he would regularly jump off the roof of his garage in order to get attention because he knew that if he broke a limb he would end up in hospital being looked after by these nice nurses and there was no downside to it yet he is now you know terribly physically scarred doesn't really you know he have no comprehension of what pain is so there is that disconnect between the human experience of pain which is common to all of us and what he experiences and I think that he feels that that is very much a barrier between him and understanding all the people around him but it's also resulted in him being terribly damaged by the inability to feel pain. Gosh it really does perfectly highlight the role of pain very much something all of us think we'd rather live without. Yes and then you see somebody who has never experienced pain and see the impact it has on them I think it makes you appreciate it in a slightly different way. Is there anything else pain? Oh I mean so much you know there are you know one woman who lost her vision as a result of multiple operations to her eye who sees visual hallucinations everywhere she goes you know I think that very much illustrates the fact that our brain even when it's starved of inputs creates its own inputs because it's so eager to experience the world you know individuals in whom is she okay? What's her experience? So she has lost her vision entirely and sees sometimes rather scary hallucinations as a result of that loss of vision you know what's really fascinating about her is that when she was asked by a doctor whether or not she would want those treated because there are some things that we can do to try and improve those she had to think very long and hard about it because she said look you know at least I'm seeing something now whether that is real or not there is a comfort to seeing something and in the end decided that she didn't want it treated. She'd rather live with the hallucinations. What else are her interruptions? So individuals who have lost their sense of smell or lost their sense of taste now you know you kind of think might I could live without my sense of smell probably it wouldn't be as quite a ritual world as I would as I would like but actually the implications of losing your sense of smell both in terms of memory you know think how important smell is for memory for those sort of emotional memories that we have you know smelling your mother's perfume or a particular meal and taking you back directly to childhood and the impact of smell on emotion on your mood on you know depression it is really underappreciated until you look at individuals who have lost their sense of smell and that was particularly important over COVID because a lot of people were losing their sense of smell as part of COVID and didn't know whether or not they would ever get their sense of smell back so all of our senses and they were depressed often they were depressed and you know it is very clearly associated with with changes in mood smell and mood are very closely linked you know if you think about some of the other um sensors so hearing so people who experience auditory hallucinations or you know in in in the man who tasted words actually I was very kindly bill Odie agreed to talk to me and Bill has been experiencing musical hallucinations for many many years so everywhere he goes in his house he will hear a soundtrack of music and you know what the implications of that are um when it was the implications so so initially he thought he was going slightly mad and he thought that actually well first of all he thought that his neighbors were playing radio very very loudly and then he thought he was going slightly crazy but actually it turned out that one of the reasons why he was experiencing musical hallucinations was because he was losing his hearing anyway and so you know it goes back to the fact that when the brain is starved of inputs it creates its own experiences because it's eager to experience life and but also the the counter-sight of that is that this association between hearing loss and cognitive decline that actually you know it's important to look after your hearing because it provides important inputs that maintain the health and the integrity of our brains so there are lots of these aspects of that you can take from clinical medicine and apply them to what it tells us about ourselves and how our own brains work how has it changed you meeting all these people and doing all this work because it can't be easier times it must have had left sort of fingerprints on you in some sort of way look I think the problem is that it's particularly when you're sitting in a busy NHS clinic where you've got a very limited amount of time to see people is you're often very much focused on the problem that is sitting in front of you and by problem I mean the issue the medical issue that is affecting that individual whereas writing these books and talking to these patients I think has given me much broader appreciation of you know what it is that we are actually doing so in you know in the NHS you kind of yes you see well look I'm treating that I'm diagnosing that I'm maybe curing that but actually you see the much wider implications on those individuals when you are addressing the stories their experiences in a much broader way you see the impacts on their families and the people around them yeah and that stuff stays with you and undoubtedly how do you take care of yourself to make sure that that stuff doesn't the honest answer is not very well really no I mean you know look I try and have downtime and I try and get away and get out of London but I think you know this is something that everybody in the NHS is currently facing everybody is feeling very very burnt out. Do you sleep well sometimes? We have a closing tradition where the last guest leaves a question for the next guest not knowing who they're leaving it for okay and the question left for you is what is the most difficult decision you ever had to make and how did it benefit you oh god I think there's lots of ways to answer that question isn't it? What came to mind? Well I think the the I can think of you know clinical situations where I've had to make very difficult decisions about whether or not to treat somebody or not to treat somebody to whether or not to whether or not to give up on somebody or whether or not to to continue working you know the sort of situation to like cardiac arrests which all doctors have to face. Personal decisions you know I think certainly making the decision to study medicine was an important fork in the road for me because you know medicine brings with it lots of amazing things and amazing experiences and we see through windows on life that very few other people get to see but it comes with it with it quite a lot of responsibilities and implications in terms of the future direction of your life so I think there are different ways to answer that. Thank you guy you write such interesting books and such interesting ways and they're all absolutely fascinating so usually I'd recommend one of them but I have to highly recommend all of them I'm going to link all of them below in the description seven deadly sins the biology of being human I've got the man who tasted words inside the strange and startling world of our senses and the secret world of sleep all of them will be linked below and the seven deadly sins book is not out until November 21st I believe so you can probably pre-order that now you can keep in mind getting that so check out the description below all of the books are linked there and thank you so much such a fascinating conversation. you (upbeat music) - Mom, can you tell me a story? - Sure, once upon a time, a mom needed a new car. - Was she brave? - She was tired, mostly. But she went to Carbana.com and found a great car at a great price. 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