Sleep and Chronic Disease: Oxford Neuroscientist Explains

[00:00:00]chronic sleep loss is associated with obesity type 2 diabetes High rates of infection and indeed cancer because we haven't ever passed this information on people don't know I think the key thing [Music] is a phrase I've heard you say in one of your talks before is alarm clocks stop the single most important behavioral experience we have yeah and that's sleep of course and and we've we've so undervalued valed sleep you know it's been treated as almost an illness that needs a cure or an Indulgence and of course in the 80s those of us that remember the ' 80s um you know people used to come and say oh I've done an all another all nighter and then people used to clap them on the back and in fact you don't want people like that in the workplace I mean essentially what we've discovered over the past sort of 20 years or so is that sleep consolidates our memory but it's not just the retention of facts it we're actually problem solving so if you want to come up with it innovative solutions to complex problems a night of sleep achieves that we're also discovering that uh the the elimination of of of be raloid this this misfolded Protein that's been associated with dementia is packaged up and got rid of whilst we sleep so much of the stuff going on within the brain and the body whilst we sleep defines our ability to function during the day and you know it's really we've got to start embracing sleep you know as I as I read through your book and as I think about the literature the work you're putting out there I think about the impact that sleep deprivation has on our entire physiology you know this idea that's been sitting with me the last few days is that number one a lot of us don't realize how sleep deprived we are yeah and I think in many ways the way we experience the world is influenced by our levels of sleep yeah I think that's what you know doing the research for for the book the realization that the tired brain remembers negative experiences but forgets the positive ones so tired individuals entire world view is influenced by by negative salience you know we're making decisions remembering the negative stuff and not the positive stuff um that's just one example I think yeah that's really profound Russell because if if as a doctor I I look around and I see how many problems we have these days with excessive negative thoughts that people struggle with yeah and then if you look at the data in terms of how sleep deprived we are yeah potentially this is the Smoking Gun that's sitting there that if all of us started to pay a little bit more attention to perhaps that would have a profound impact on the way we feel and as you say these negative thoughts and across the whole demographic from from youngsters uh and Young young youngsters all the way through to the to the elderly uh I think it could make a huge difference yeah so we're recording this uh late morning uh it is just passed midday so I know from your book now that we've just passed the danger zone the most dangerous part of the day right so I feel good so we should celebrate with the glass it's 12:01 so can you explain a little bit about what is so dangerous about mornings and in particular this 6:00 a.m. to 12:00 p.m. time period yeah but well well the the biggie of course is stroke and heart attacks between 6:00 a.m. and 12:00 noon there's almost a 50% greater chance of having a stroke or heart attack and of course it represents the sort of the biological switch from the Sleep resting state to the active state so so what our internal clocks are doing is anticipating increased activity so even before we wake blood pressure is going up the mobilization of glucose is going up um interestingly this the stickiness of platelets is going up presumably anticipating an increased risk of of damage and therefore the need to clot uh and so cortisol is all all going up mobilizing our bodies for activity now if you're healthy it's not an issue in fact it's a it's a wonderful adaptive response so you can get out into the new environment and exploit it to the full but if you have health problems then that surge in blood pressure that increased stickiness of the blood is going to predispose to things like heart attack and stroke and and what's become very clear is that when you take your anti-stroke medication your anti-hypertensives really matters so for example taking them before you go to sleep before bedtime rather than first thing in the morning over a sort of four fiveyear window uh can actually half your chances of having a stroke or a heart attack now that information isn't widely known and and I think we've got to try and get this sort of this this this sort of knowledge more widely accepted yeah a couple things came up for me there Russell I remember I'm going to guess seven or eight years ago I was getting quite frustrated as a medical doctor with my lack of awareness over all kinds of things to do with our lifestyle and how it influences health and I was thinking if I knew a bit more about this and how to manipulate it I'm sure I could help my patients more so I would go in my holidays around the worlds of various conferences I remember in America sitting at a conference and there was a cardiologist called Dr Mark Houston and I remember him saying exactly this to me years ago he was saying something like most blood pressure medications should be taken in the evening and I'm thinking wait a minute we're giving them all that in the morning and people are just taking them in the morning because it's easy it's with breakfast I'll just take it so I think that was the first time that that lodged in my head that oh the timing of these medications is important the other thing Russ that came up for me as you was speaking there on the show we've spoken a lot about stress in the past and what happens when the stress response gets activated yeah and what you just described happening then in the early hours just before we wake up those are the those are the things of the stress response blood being more prone to cloting blood pressure going up cortis going up so it's almost like a mini stress response first thing in the morning it indeed it is yes absolutely yeah stress gets a bad WP I mean you know it's it's a it's a shame I mean I i' liken stress um as the sort of the first gear in in in in a car you know it gives you that wonderful acceleration so it's great you know um but if you keep the engine in first gear of course you'll destroy it and and that's the problem with so much of our stress these days it's not that it's an acute quick shift where for example night shift workers they're running on stress to keep awake and to keep functional during the night shift and so no wonder there's all those health problems associated with that group Yeah you mentioned the clock and there's there's a lot in your book about our body clock our body clocks I should say and what they all do what influences them one thing I've felt and experienced when people when my patients when members of the public are thinking about sleep they're often thinking about the evening they're thinking about what do I do just before bed what do I do do in those hours preceding me going to my bedroom and of course that's important we're definitely going to get to that but I thought it would be useful particularly through the lens of the clock I guess talk about the morning why is what we do first thinging in the morning so important for our ability to sleep at night yeah so we have this this circadian system this sort of internal representation of it a biological day and what it does is anticipate the very demands of the rest activity the sleep wake cycle now for it to be of any use the internal day needs to be set to the real day the astronomical day and the classic mismatch between biological time and environmental time is jet lag and we eventually get over jet lag as a result of exposure to the the light dark cycle in the new time zone but what we require in any time zone is daily exposure to the light dark cycle and particularly morning light for 90% of most of us have either a long body clock or a body clock that's slightly longer and so it will naturally drift a little bit later and later and later each day and the effects of light are not the same Morning Light advances the clock makes it makes us get up earlier and go to bed earlier whereas dusk light delays the clock it makes us go to bed later and get up later and so what Morning Light does to us is take this drifting clock and shoves it forward a bit into time so it's beautifully aligned now of course this is important at every level I mean we did a study a few years ago on on teenagers and we found that and all over the world um and found that the later the chronotype the eveningness versus morningness uh the greater the evening light these young people got so they were getting up after morning um so not getting the Morning Light which would Advance the clock but they were getting evening light which would delay the so part of their their going to bed late and getting up late is when they were actually seeing light and so morning light for most of us is really important to set the biological clock which then aligns all of our activity including the sleep wake cycle to the appropriate time of day yes this is fascinating there's so much there so we live according to 24hour days yeah okay but one thing I'm aware of from your book and other research is that our internal clocks are not set to exactly 24 hours so I want to I want to talk about that and why you think that might be because we certainly I guess didn't evolve for plane travel in the future you do you know what I mean so so so when we go on a 12-hour flight to LA from London we can adapt straight away right so that presumably wasn't Evolution's goal so I'm interested as to why it's not 24 hours in your view but also you say Morning Light so does it matter what time of morning light that is you know can people get it at lunchtime are we talking as soon as people wake up and of course that changes in the seasons right so can you help us put all those things together okay so why isn't the human body clock exactly 24 hours well now here's some hand waving because the the modelers say that if you want two oscillators to align into each other two rhythms one is fixed obviously the the rotation of the earth is fractionally under 24 hours and if you want to fit a a body clock to that it helps if it's slightly different from 24 hours because then it can align more easily now I don't pretend to understand the mathematics behind it but that's why why it is but there's a there's an even so mother nature knew what she was doing as always I mean but the really interesting question I think for me is why is there such diversity in the human chronotype so the you know the fact that we have some people you know are really early Lars and some people really late hours there's a huge diversity you know to the extent that you can almost bed share in some extremes whereas if you look at the mice or any other animal you want to study it's all very very similar and I think this is something that that's puzzled me for ages and it may well be that in our society you know and we've we've we've only moved very rapidly from sort of essentially small groups tribes interacting it may have been useful under those circumstances to have vigilance across the 24-hour day and having some people that were sort of awake early um and could perhaps alert the group that there was Danger from another tribe for example or or or some sort of animal and that may be why we've retain this extraordinary diversity it's very we're very weird as a species in that regard yeah I mean that makes a lot of sense doesn't it you mentioned the word chronotype yeah I wonder if you could just elaborate exactly what does chronotype mean and then you also mentioned owls and Lars and I'm really interested in this because a me and my wife appear to have slightly different body clocks but many people I feel certainly if I look at my clinical experience Russell and this also I think speaks to this idea that the body clock isn't quite 24 hours that we can manipulate it depending on what we need it to do or what the tribe needs or what the weather is right A lot of the time I think well are evening types really evening types or are they evening types because of the modern light environment yes um so yeah quite a lot there yeah yeah okay so so what defines your chronotype whether you're a morning person or an evening person and there are a number of factors the first of all is one's genetics we now know that the clock genes and the proteins that they make subtle changes subtle polymorphisms in those genes are associated with morningness and eveningness so by their contribution to our genes our parents are still telling us what time to get up and go to bed at some level so that's the first thing through development are chronotype changes so from about the age of 10 we want to start to go to bed a bit later and a bit later our lateness peaks in males at around about 21 21 and A2 in females about 19 19 and A2 and males Peak later they have a later chronotype than females then from those late teens early 20s we start to move to a more morning chronotype so by the time we're in our late 50s early 60s we're getting up and going to bed on average when we got up and went to bed when we were 10 and that sort of basically Maps the changes in some of the St steroids testosterone and estrogen so it's thought that there's a a very important hormonal mod modification of of of of the clock so that's within individuals we've all got like so whatever I'm born with let's say I was born a morning type and I think I'm a morning type then when I'm 10 in my teenage years that's going to be pushed it's going to be later and later yeah as you say for most males will Peak at 21 and then it's going to start going back again but what about between individuals there's variation there as well right yeah a huge individual variation I think that's a really important point because you know terms of our sleep weight patterns and our chronotype there's massive individual variation and and you know um there's on average about a 2hour difference from somebody in the from in their late 50s early early 60s to somebody in their late teens so asking a a teenager to get up at 7:00 in the morning is like asking a a 6-year-old to get up at 5:00 in the morning now does that matter I guess there's a real interest here for me given that my son's 12 about to enter uh these teenage years yes and as a family we prioritize sleep what we certainly have done but I'm I'm already noticing with him a change yep in terms of his desire to do what he has done in the past let's put it like that okay I think they called it testosterone poisoning don't they and what I'm interested is when we say teenagers want to go to bed later and wake up later and we think about their chronotype what if that teen teer still went to bed early so what's driving the change is it the fact that they're going to bed late therefore they're having to stay in bed later like could that be environmental School pressure that sort of stuff or do you know what I'm getting absolutely well of course the the other Factor the sort of as it were the the the biological factor would be when you see light as we as we just discussed sort of Morning Light advances the clock evening light delays the clock and teenagers particularly over the weekend will miss the Morning Light making them get up earlier but they get the evening light so they or the afternoon evening light and so they'll go to bed later so those are the three sort of biological uh factors but then we have to add a couple of other things one is of course the use of social media uh it's very interesting many teen teenagers appreciate that they shouldn't be using social media into the early hours of the morning uh but they feel uh that sense of being connected to their group over overrides that knowledge about why it's important to be asleep so there's that element and in fact it's really fascinating some Studies have shown that that lateness can be hugely late so what happens of course is that they have very shorten sleep they're driven out of bed by an alarm clock or a parent they struggle through the school day often and when you teach you know talk to many teachers kids are actually falling asleep at the desks so then they finish school and then they have not just a short nap but can be a nap of 2 hours or so which then pushes back the pressure to sleep that night and so so you know the the desire to use social media and the fact that they're not as tired because they had to sleep in the late afternoon means that they can function later um uh at night and they get that shortened sleep and in fact you have to be very careful because it can lead to increasingly shorten sleep at night and longer naps after school which you know and can fall into this sort of feedback loop of really disrupting the sleep if that teenager could go to sleep let's say on time at a more suitable time given what time they have to get up for school or the school bus or whatever the sort of fixing that they can't move does the later chronotype still matter I.E if they shift their environment so actually I'm still going I'm going to go to bed earlier I'm not going to expose myself to evening lights this may sound optimal and hypothetical or something that's practically impossible but in theory would that then normalize things do you think yeah you can shift teenagers to an earlier chronotype because of light exposure absolutely uh practically it's it's it's very difficult um but it's it's in theory possible yeah and this light exposure whereas in the morning it advances the clock and in the evening it delays the clock so pushes it back what life exposure are we talking about here because let's say in the evening or at dusk you saw natural lights not artificial lights does that still do the same thing it pushing it back or does that have a different wavelength that doesn't affect us in the same way well you you're you're sort of impinging upon what i' I've sort been working on for a long time which is how does how does light interact with the body clo book and the first sort of extraordinary finding was that the visual cells within the eye the rods and the cones are not required to detect that dawn dusk cycle there's a third photo receptor within the eye and and and those and we've been working out most recently how those receptors interact with this sort of Master Clock within the brain so that's one thing the second thing is that these photo receptors need quite a bit of light so we don't really appreciate our visual system is so good but we live our lives in dim dark caves so uh shortly after Dawn um natural light is some 50 to 100 times brighter than average domestic light conditions um and and so really what the clock is looking for is a bright light signal and so we're talking in the hundreds to thousands of Lux range so if you think of of natural light okay Moonlight would be 01 Lux um and a bright sunny day even in the even in the UK can just about get up to 100,000 Lux and those those weird amazing photo receptors need as I say this sort of 100 to thousand Lux range now it's complicated because it depends upon how long you're exposed to that light so you can compensate to some extent for a lower light intensity by increasing the duration and it's worth bearing in mind until the the late 80s it was thought that the human circadian clock was not regulated by light at all because when people use sort of relatively low levels of light that would shift the biological clock or entrain the biological clock of a mouse had no effect at all this is in the 1980s right yeah I read that this morning in your book and and that shocked me because 1987 right I was just finishing Primary School it it's not maybe it is but it doesn't seem that long ago to me and I thought when I read that I I had to reread it this idea that back then which wasn't that long ago we didn't think light hugely influenced our Cadian Rhythm and now that's considered fact and I think well what else is going on that we don't know at the moment well that's what's so exciting about this field but I I remember you know doing doing my my PhD um and I I got my PhD in in in ' 84 and uh you know when you did public talks or anything people say well well how is it regulated so it's primarily social cues and food and I remember being actually at that first presentation in in 1987 and you know it was an audible gasp around me oh my God you know you just need a lot of light and of course now we know light is incredibly important for the regulation of human cading rhythms but you need quite a bit of it and this is where we fall into some problems because there's a lot of stuff out there saying you shouldn't look at a at a Kindle immediately before you go to bed because it'll shift the biological clock so the most detailed stuff study which was from a group at Harvard asked people to look at a a Kindle on its brightest intensity 4 hours before bedtime and they asked him to do this on five consecutive nights and after that on the on the fifth day uh sleep was delayed by an average of 10 minutes and it was just statistical and as one of my colleagues said um well it may be statistically significant but it's biologically meaningless wow and so but we do know that light in the evening can delay the clock but how much and what intensity and for how long is still being resolved clearly the brighter the light and the longer you see it before bedtime could shift the clock but what we do know that light is doing is increasing alertness and therefore delaying sleep onset so it's probably not the light from the devices changing the clock but it's the light from the devices changing alertness and therefore delaying sleep yeah super super interesting so if we just stick to what that study showed that was on a Kindle I know one I've heard you speak before that you regard Kindles as quite different from smartphones or looking at social media perhaps you could explain why that is well because a Kindle is is is fairly you know you're just reading it basically where as a smartphone you're checking your emails you're looking at social media you're checking the news you might even be listening to music at the same time and so these are really Interactive devices and they will be increasing alertness and therefore delaying sleep onset yeah super interesting in terms of Lights just to finish off in the evening then we talking about the complexities of Lights you know how much how long for all these kinds of things some people who are promoting health and well-being are talking about the importance of morning lights morning natural light I know there's one neuroscientist in America who talks about getting 10 to 30 minutes if you can yeah within half an hour of waking up okay so that's very clear guidance I want to I want to know your view on that the data are good for that I mean really really I mean so for example the the Ken Wright's Studies have shown beautifully that Bright Morning Light real light not artificial light can advance the clock and and really shift individuals you two hours earlier so there's there's no question about it and you can mimic this in in the lab as well so for example 10,000 Lux for 30 minutes uh from a light box will also set the clock so so the data are there pretty solid now we say Advance the clock what if someone doesn't want to advance their clock and they wake up and they're like you know what I've got a a late work night out tonight and I won't be back for my normal time I I've never thought of this question before but I'm just intrigued might one then think hey for tonight I'm actually going to not expose myself to light for a couple of hours because I want to delay that or is that hard to it you it probably will have a small effect I mean the the tricky thing is for those 10% of individuals who are really mourning types and and it's it's a shame really because most of their their colleagues will be intermediate to late types and of course they will be then forced on a Friday and a Saturday evening to stay up Way Beyond where they want to be and they sort of complain bitterly that um you know God all my friends don't want me to stay up of course for the work environment it's great they can get up you know go to the gym early and then go on to work whereas most of us who are late types find that a struggle so you're happy with that 10 to 30 minutes natural light recommendation would you would you would you ideally have people do that as soon as they can after waking certainly the the the earlier the bigger the the effect yes and it's and it's very important um ac across the Spectrum so for example in the nursing home environment up until fairly recently the light in those uh nursing homes is really low I mean terribly low some cases in the television room it would be just sort of 10 20 Lux I mean crazy low uh now people are realizing that if you increase the light in the day spaces then you can actually improve the sleep wake behavior of of of individuals in a nursing home and where it's been looked at in individuals showing mild dementia you could actually improve cognition by 10% simply by increasing the light with inside and and also using other tricks like you know having breakfast by a window where there's a lot of light coming through W that's fascinating and then in terms of evening I want to draw a distinction between natural light and artificial light so let's say you live in a country where you have long light evenings at particular times of the year like the UK for example you want to get your morning lights in the morning which is clearly a lot easier in a UK summer than it is in the winter Y what happens if you want to be outside in the evening so it's it's still natural it's not your screen it's not social media it's not the news it's not all that attention stimulating information is there something going on in natural light where actually you know the evening light perhaps doesn't shift the clock as much or or or or or does that still do it well of course when we're all agricultural workers we got symmetrical exposure to Dawn and Dusk and so you know the morning light would Advance us but then that was counteracted by the The Dusk light which would delay us and so it so it was fine and the problem that many of us face now is that we get asymmetrical exposure to the dawn dusk cycle which invariably means most of us will miss morning but get lots of of dusk light uh and therefore get up later we'll delay the clock now in terms of the quality we've we've talked about the intensity we've talked about the duration um but we should also touch about the color the we wavelength of light now those specialized photo receptors are maximally sensitive in the blue part of the Spectrum in fact intriguingly if you look at the blue of a really beautiful blue sky that's where they're maximally sensitive um so so there's been a suggestion that actually only blue light is important but again it's more complicated than that because the response is like a bell-shaped curve it's maximally sensitive in in in the blue but of course it doesn't mean that they won't the receptors won't detect shorter wavelength uh or indeed longer wavelength light again it's how long you're exposed to it we also now know which is turned out to be really confusing that the rods and cones which we know are not required for the regulation of the clock talk to those specialized photo receptors so they can modulate their activity some of them some of the rods and cones seem to add sensitivity and others seem to inhibit the responses so it's turning out to be really complicated um and we don't fully understand why so the best advice would be let's say someone is trying to get on top of their Cadian Rhythm and their sleep and they feel either for work reasons or for other reasons they're going to bed too late the best advice at the moment would be to try and limit light exposure in the evening even if it's natural light you still want to be a bit careful yeah and and if you are an extreme late type and you really you're struggling then what you need to do is um set the alarm and either get outside first thing in the morning or get a light box which will advance the clock and make it easier for you to get up for job or or whatever reason yeah I know you were on uh the Chris Evans breakfast Show recently talking about your book and um I remember in that conversation Chris said because he for many years is you know presenting on live radio I think at the moment it's 6:30 a.m. and I think he said to you that he goes to bed at 7:00 p.m. or he at least puts an ey mask on at 7:00 p.m. so it's reducing how much light is coming through his eyes I think he said in that conversation with you it had a massive difference and then when he wakes up at 4:00 a.m. he puts all the lights on his bedroom as bright as possible yeah and that's really interesting and I know he was saying it's had a huge difference for him and of course it maps onto exactly what we know about the system he's doing exactly the right thing for what his requirements are which is to get up early and then perform early yeah and this is where I feel it's very empowering for people even if they were to find out their chronotype and them to find out that man my job is actually in disharmony with my natural chronotype you can do things can't you to manipulate it so you're maybe not as vulnerable as she might have been that's right and and I I think we tend to feel as though our body clock is this fixed thing just like our sleep wake cycle and it's not it's Dynamic and influenced by a whole range of different factors that can be tweaked to our advantage yeah so interesting you know Russ one of the things that's helped my sleep a lot over the past years quite a few things we sleep one is to avoid any sort of emotional stimulation in the evening so I've this has probably been for six or seven years now I've had to educate the people around me particularly my family that I I I go to bed early I wake up early I just it's suits me I don't know if I am actually a morning type I certainly live like a morning type but then I set everything up around that because ever since my kids were born they've always got up really early and I know for me I'm a much better human being when I've had time to myself in the morning before anyone else is there so I would shift it back so that I could have an hour to myself before they wake up so I'm I'm now in a position where I usually go to bed by 9:00 at the LA and I'm up by 500 a.m. at the latest when I can stick to that consistently I feel fantastic yeah and that's exactly what we should all be doing we should be defining you know what what our biological needs are and also of course what our social needs are or societal needs are and particularly our work and try and tune uh ourselves accordingly um it it you know it's it's so important yeah and so that that process required me to help people around me understand that look after 7 half s I really do not want to be contacted with anything unless it's an emergency I know and and of course it's very difficult because of course um towards bedtime is the only time when many couples get chance to talk about stuff but of course it can be charged and so so for example I have banned any discussion of family finances before we go to bed or anything like that you have to carve out time at at a different time the other thing that's interesting about your earlier bedtime of course is you'll be eating much earlier yeah and that can be very important and the data now are very clear that trying to concentrate one's calorie intake during breakfast and lunchtime and a very light supper or an earlier supper that you can possibly manage um is better for our metabolic health and reduces the chances of weight gain uh obesity and and type two diabetes so so you you have a a double Advantage there by going to bed earlier yeah well we'll come back I think that's a really important point and that really speaks I think to this wider issue which is a lot of the things that we would optimally do to optimize our cadan rhythms optimize our sleep optimize all these different functions in in our b sometimes have to be done in conflict with what Society yeah is driving us to and I think there's a much wider piece there just to finish off on lights at least for the for the moment cuzz I think it will keep coming back and it's so important one of the things that has really helped me over the last years is you know I I try my best not to be on my screen before beds uh usually I'm good with that although I'm human and you know I fall pray to the Temptation like anyone else might do I try and read before beds and in my bedside lamp I've now changed maybe for a couple years maybe not even quite that long but certainly recently I put these low Lux bulbs in so I've got this like Amber low Lux bulb now I really feel it's made a massive difference the way I feel it just feels softer and whenever if I'm in another room or staying somewhere where they've got a usual bul and I think wellow this is quite obnoxiously bright so are these things helpful in your view they are indeed um it it sort of maps on again to the to the biology this is what you you'd certainly recommend um because the low of the light you'll reduce alertness and it'll be easier to get to sleep and of course if it's bright light then of of course you will shift the clock but but um you know most most artificial light is not going to have much of an effect uh but the other thing of course is that what you're doing is defining the sleeping space um and so for example you know we've we need to sort of reinforce the fact that the bedroom or the sleeping space is what you do when you want to go to sleep so you you know have a lovely mattress you have great pillows you you might even have a distinctive smell like lavender or something else because you associate that distinctive smell with the Sleep State and I know people who when they go and they they travel and they're staying in a hotel room they'll take a partner's perfume or after shave because that defines the sleeping space for them so the extent to which those are almost Placebo effects doesn't matter if they work then it you should embrace them when it comes to Blue Light blocking glasses yeah I'm interested what your views are before you answer that I would say as a clinician what I have found is for some people they appear to have been transformative mhm now what does the science say what is your view based upon all your years of research yeah I mean I mean blue light blocking glasses were sort of originally introduced because it was thought that blue light would promote age related degeneration and the evidence for that is a bit mixed certainly you'll get more damage with blue light in uh a laboratory setting so sort of if you expose cells to to to Blue Light there's a greater chance of of those cells um undergoing apoptosis that you know those cells dying as it were but when that's translated to the Natural realm it's not clear that blue light is having um much of an effect on age related macul degeneration this has also been to studied in the context of of um cataracts so for example uh blue blocking lenses have have been introduced to reduce uh the blue light getting in and therefore age related macular degeneration the evidence for that um Is Not Great there was a lot of concern that these blue blocking lenses were also going to disrupt the clock because after all the clock is maximally sensitive to Blue Light uh we've done some studies showing that it doesn't matter whether you use a blue blocking or a UV blocking uh it doesn't and in fact it's quite interesting most artificial lenses allow less blue light through than a natural lens so we would be naturally exposed to more blue light anyway so uh I don't I I think that's where the sort of the origins of these these these lens these blue blocking um glasses and things are used now in terms of the Cadian system and the arousal systems we do know that blue light is the most effective wavelength and chrisen Ken has done this from Switzerland in uh increasing alertness so if you want to reduce alertness in the evening it's likely that a blue blocking set of glasses will be useful will it be useful in terms of the clock well possibly um but it depends again how long how bright the the environmental light is I guess this speaks to a much wider point which I think comes through in all the work all the talks I've seen of yours everything I've read in your book is this idea that sleep is highly individual yeah and I know there's many myths out there that you're Keen to bust one of them being that we all need 8 hours yeah yeah I mean that was part of the motivation for for writing a lifetime because I think that there's been a tendency to to feel that you know we have to have a certain you we got to get eight hours and I remember one person came up to me and they said I don't get 8 hours of sleep am I going to die and I sort of said well I can assure you you will die but it may not be anything to do with not getting eight hours of sleep and you know because I'm being a bit flippant but but actually the natural sort of span for humans is 6 hours to maybe 10 10 and a half hours and so that's in the in the natural range and I think people get very anxious that if they're not getting 8 hours you know they're going to it's it's going to be a disaster now I think you have to be careful um because the the tired brain is very good at fooling itself that it's okay so you need to really be uh tough about assessing what your sleep needs are um and if you can function optimally during the day if you're feeling fine then chances are you've had a good night of sleep if you need an alarm clock to drive you out of bed in the morning if it takes you a long time to wake up if you crave caffeinated drinks if your family friends work colleagues say oh you're being a bit you know where's your sense of humor you know you're a bit more irritable and critically if given the opportunity to sleep longer on free days or indeed on holiday you sleep much longer that's all telling you you're not getting enough sleep so what we all have to do as individuals is Define how much sleep that we need for optimal daytime performance and I guess that would also depend on what we're doing right because let's say I don't know that you have defined that hey you know what I keep hearing about the say hours but I think I sleep for I don't know 6 hours 30 each night or 6 hours 45 and I'm fine and I wake up without an alarm clock and I'm got energy and I feel emotionally quite with it you know yeah but then let's say you start I don't know training for a half marathon or maybe at the weekends you go on long runs or something it's also that awareness to go well yeah in the week I may be okay with this amount but actually if I'm really exerting myself physically and have a desk job Monday to Friday maybe I need more at the weekend and I guess the reason I don't know what your view would be on that one of the reasons I asked that is because I I think Roger federa is well known to is it 10 hours or 12 hours a night he I think he talks a lot about how much sleep he has and how important that is to his Optimal Performance as a tennis player a few little suties there do you think physical activity levels um make a difference in terms of how much we need and I guess how would you put all that together well of course the the famous long sleeper was Albert Einstein um who basically sat at his desk for for every day um and he needed he he craved 10 hours of sleep so I think that it's probably influenced by athletic performance and certainly um there are some data suggesting that really strong training is associated with slightly longer sleep but it's not an overwhelmingly increased amount of sleep uh and I think you know federa just needs that amount of sleep um and for his Optimal Performance same way that I Einstein did and you know in the book I took I compare Einstein to Salvador Dary you do um and um you know I sort of it's great you undergraduate lectures I say well Einstein you're Classic sort of slept 10 10 and a half hours so perfect example of long sleep genius and then you know one of the students said well what about Salvador Dary you know he only he he didn't sleep at all really and his trick was of course to hold a a metal spoon um in his hand and sit in a chair and when the spoon dropped from his hand when he fell asleep it hit a metal plate on the floor and woke him up but of course Dary was the first to recognize that his altered state of mind because of his chronic lack of sleep gave him the sort of surreal Vision to generate the art that he generated um yeah so it depends what's the goal it depends what the goal is the goal is to hallucinate and have an alter State of Consciousness and you need that for your job you know what sleep deprive yourself all you want yeah that's true it may make you impossible to live with um as darly of course was so yeah but but if you want an alter State of Consciousness then decide you know deprive yourself of sleep well maybe now was a good point in the conversation to make the case for sleep right first of all how sleep deprived are we as a society and then secondly what are those consequences yes uh sleep deprivation varies a lot because of course sleep need varies a lot um but I think on average people are saying that we're sleeping one maybe 2 hours later less than we were in the 1950s and I and I I'm I'm I think those data are pretty robust and certainly that's the case in in adolescence big time um and so what are the consequences well short-term sleep loss we see changes in our emotions uh and our cognitive performance so uh we increased levels of irritability the failure to process information accurately we do stupid and unreflective things we are less empathetic I it's really fascinating you we we fail to pick up the social signals of friends and family um we're less socially connected we have a reduced capacity to remember things we are less creative um so all the things reduce sense of humor I mean you know all the things that make us this extraordinary creature you know this amazing humans you know all this creativity and wonderful and interconnectedness goes as a result of of of even short-term sleep loss longer term as many individuals are experiencing at the moment is associated with this falling asleep uncontrollably so microsleeps and it's estimated in the states that 100,000 crashes on the American freeway are as a result of people falling asleep at the wheel the American Automobile Association suggests it's much greater than that perhaps as high as 300,000 and of course if you're falling asleep at the wheel you you can't stop yourself so those crashes tend to be really bad crashes we also see that there's changes in immune responses so it's likely because we're chronically tired we're activating in a sustained way the stress axis and that's going to push up blood pressure it's going to throw glucose into the circulation so it pre then disposes to things like obesity type 2 diabetes and indeed because of the suppression of the immune system high rates of infection and indeed um cancer some very convincing studies showing that night shift work for example night shift nurses have higher rates of coloral cancer and breast cancer in fact those data are now so good that the World Health Organization has listed night shift work as a probable carcinogen so so I I think the really key point is that chronic sleep loss is so much more than feeling feeling tired at an inappropriate Time It's associated with an impact upon our health at every level yeah I mean what you just went through there it it it impacts negatively our our day-to-day lives you mentioned empathy I mean what do we need for good quality relationships with Partners children work colleagues family we need empathy yeah and and and or invariably in the workplace you need creativity you need people to be able to work together you want to reduce irritability you need often a good sense of humor and so really we should be really promoting good sleep to improve productivity yeah it speaks to something you said earlier on in our conversation that when we are sleep deprived we forget all the positive experiences and remember the negative ones which of course completely Alters your view and perception of the world it feels like this dark scary place rather than an uplifting hopeful joyful place you mentioned yes these short-term consequences but also these pretty scary long-term consequences now one thing I really appreciate about the messages you try and put out there into the public is you you really seem to be trying to help promote Health without scaring people now of course these statistics are scary and there's two groups of people I want to keep at the Forefront of our mind now as we think about these negative side effects with mentioned shift work and I want to talk about shift work because what I read in your book is that one in8 UK workers currently are shift workers that's probably only going to increase that's a lot of people and I can't imagine what it's like for shift worker to just hear what you said the wh say which is a probable carcinogen that's not a nice thing to hear no if you work shifts if you're a whatever if you're a nurse looking after the people to help their health and you think yeah but at the same time I'm Wrecking mine in the process so shift work is something want talk about but also the other thing I've noticed as I've been trying to raise awareness of sleep now in books and podcasts for maybe 5 years unwittingly we can often end up scaring people and making them feel worse and more anxious now young parents often will get in touch and say look you know love what you love what you said you I understand about sleep but I'm really worried my three month old doesn't sleep through the night you know or whatever is going on so many parents get really scared when they hear this sort of stuff so if we address parents first of all shortterm sleep deprivation longterm is it okay for a few years if a parent sleep deprived you know help us sort of get less scared about that if you can yeah well I think there's two issues here I one thing that that our society or the in the developed Nations at least uh has shifted very rapidly from the extended family to the nuclear family where the parents become the sole providers for their children um and it's usually the mother and uh what's happened up until fairly recently is that child care was a distributed activity and so when the mom got tired there was an aunt or a sister or a friend who would take over so that the mom can get some sleep and if you look at the primate societies uh you see that uh care is distributed across the group we have never evolved to be the sole parents as it were of of our children and I think the first point to make is that young moms in particular but but but but both parents uh should not be afraid to reach out and I think there's this sort of terrible guilt that I can't cope because I'm feeling tired well no surprise we never evolved to to look after our children in this manner so before babies are born it's really important to think about the support network that you can put in place to to to try and mitigate some of the The Chronic sleep loss now what's are the long-term consequences of this it's it's not clear uh I suspect that there are probably buffers that kick in that actually um prevent some of the some of the damaging effects of of chronic sleep loss during those sort of few months I don't know um and in fact I think it's a really important area o o of study yeah I think you know what you said there I think is really helpful first of all just recognize that the way we're bringing kids up now is tough yeah we never had to do it like this you know recently Russell my wife's father has been away in Kenya for a couple of months his family and my mother-in-law has been staying with us on and enough for a couple of months and let me tell you the difference you just it's it's little things but just having a third adult in the house yes when it comes to child care it it's not just one more person it it seems to have changed everything the whole dynamic Chang the whole dynamic changed I was like this is incredible this is what humans have always done yet many of us have moved away for work opportunity we don't have those support systems so I thought that hopefully takes the pressure of people to at least go yes I know it's hard but yes it is hard it really is hard you're not you're not broken it's not that you can't cope no none of us can cope with that so I think that's a really nice message but also that message you can reach out you know yes maybe you need to phone a friend and say Hey listen I'm knacked could I just have a nap could you come while I have it's not a sign of weakness it's it's actually you know embracing our biology in a sense um and and I it's it's tragic that I think that young parents don't know that um and feel guilty about it it's it's simply wrong and and it's you know so many unintended consequences that we're facing at the moment and and sort of with increased wealth and Independence you know we think right you know we don't have to live with our parents anymore or we can move a long way away from them and yet we've we've lost something in the process I mean I was you know my I my I very close to my grandparents who looked after me while my my mother was working and it was a as you as you say it was a meent you know a big thing so Mommy's coming home and it was all you know excitement and and you have that Dynamic environment um and clearly you know we are where we are but but people shouldn't be afraid to reach out I think that's so important let's talk about shift work um there's all kinds of things there's a huge section on shift workk in the book which I think will be very helpful for anyone we mentioned how many people of course our shift workers we mentioned their potential health problems off that yes you know something I read in your book which I found fascinating was that over 90% of night shift workers was it even 977 yeah they don't adapt no and and so that's going back to light again so you've got relatively dim Light Within the workplace within the office or the Factory and then of course on the journey home uh or on the journey in you're going to or during the day you're going to experience bright natural light and the clock always defers to The Brighter light signal as being daytime so the Assumption for by employers just say the clock always defers to The Brighter light signal I think that's a really powerful thing that's why we don't shift and in fact there there's one group um there's a lovely study from the University of s Josephina rent and you know that that 3% some of them are North Sea Oil Workers because what happens is they're out on the rig at night under these great Arc lights and then they're in windowless metal boxes during the day and they do switch and so they become nocturnal as it were wow then of course it's really tough for them because then they have two weeks of Shor leave and they're completely maladapted to their friends and family but you know the serious issue is you you you don't adapt and and and so I remember chatting to uh the chairman of the CBI oh many years ago now and and you know giving a speech saying we're going to cure the problems of British industry by running running on a 24/7 basis no need to build lots of offices in London you know the rush hour etc etc deeply well-meaning individual no idea of the biological consequences and the assumption that that the clock will adapt to the demands of working at night and for 97% of people it doesn't we're not machines we're human beings right absolutely yes and I think you could you could you could apply that across all kinds of different things in society it is fascinating because we we are achieved so much I mean you know it's we shouldn't I mean it's phenomenal what we've achieved as as a as a as a as a species um but we are it comes with some some massive arrogance and what we've assumed is that we can do whatever we like whenever we choose and because we've invaded the night cheaply with electricity since the 1950s onwards we've invaded the night and have thrown away that really important part of our biology which is sleep that's interesting it was only in the 1950s when we've big acceleration when we've really aggressively invaded that's not long no through in evolu lands that's just a blink yeah and and clearly you know we've been creeping in you know the aristocrats are using candles and in fact a sign of wealth was you would eat later in the evening and you'd light your but remember a candle you know in the early 19th century was the equivalent of a of a working man's daily wage so only the rich could could have light and of course why would you burn fat which is what candles were made of when this is food and of course food was incredibly scarce for so many people working people 200 100 years 150 years ago we'll stay on shift work for the minute but this doesn't just apply to shift work driving driving tired and a pretty alarming statistic in your book about what it means to drive at 4:00 a.m. for most people yeah there's well well Drew Dawson has done a wonderful study Drew Dawson's based in Australia and he compared the cognitive performance the loss of one's ability to process information um across the day and found a very you know poor cognition around about 4:00 in the morning where where it got to its lowest point um and he compared that with the loss of cognitive ability with consuming sufficient alcohol to make you legally drunk and on the scale it was about a minus5 um dropping cognition when you were legally drunk but at 4:00 in the morning it was minus 20 so so if listeners take nothing from from this at all other than the fact that you driving at 4:00 in the morning your ability to process information is worse than if you were legally drunk okay this this is big right because we've touched a few times on this this whole societal condition what we're being asked to do now or what we think we have to do to fit in with Society versus what's biologically optimal some people of course have to get up early for work some people now drive through the night FL we drivers you know big big cargo in the back um now I'm sure they've got certain regulations certain things that they do in order to be less tired yes uh at that time but you know driving at 400 a.m. yeah for most of us being worse than when we might be legally drunk that's pretty alarming it's extraordinary because also then let's think about look I'm I don't really this anymore but if I think about my social culture in my 20s and 30s you know you go to a mate's wedding right there'll be some late nights a few drinks then you drive home on the Sunday you know yeah you you you know just to be super clear you know you you're fully sober yes you know but it culturally it's okay yeah I'm knacked I've got to drive now for 4 hours but we're pulling people's lives at risk not just our own we're putting other people's lives at risk so culturally this idea driving when tied I think is something we all need to face well I think it's like smoking we're not only um endangering our own health but um the collateral damage is that we harming uh other people do this yes and but I think it's again it's it's a matter of education and a failure to appreciate um you know Junior doctors a study published fairly recently showed that 57% had either had a crash or a near Miss on the drive after the night shift uh so so now again we're going into scary territory but the key point is there's stuff we can do about it we're not going to put the 24/7 Society you know Genie back in its bottle so what can we do to mitigate some of these problems well knowing that we're going to be vulnerable to having a crash on the drive home then we sh or employers and I think there's a serious duty of care here is they should make available or subsidize the use of devices you can put on the dashboard that measure head nod or the fact that the car is veering and alert you to that and and that that you know an alarm goes off and make sure you you know you're woken up and of course many highend German cars now have this technology built built in yeah um but that's something that that that could be done knowing that um night shift workers have higher rates of cancer coronary heart disease diabetes 2 etc etc why don't we Institute uh higher frequency health checks you know every six months for these individuals to catch these conditions before they come become chronic what food do we provide for our night shift workers you know High rates of cancer you know coronary heart disease all the rest of it high fat high sugar nobody to my knowledge is actually supplying easy to digest high protein snacks to their Workforce throughout the night now It's tricky because if you're tired you're programmed to eat more sugar um but but at least we should make that option available why why high protein um because it doesn't have the same impact as carbohydrates and fats on coronary heart disease and in De cancer but that would be quite easy right let's say for a hospital which is staffed at night it would be quite easy either to have those snacks or to work with a nutritionist and make in bulk protein shakes full of phytonutrient rich foods that are easy to digest that are tasty that they could give people it it's not that hard no and and in fact I think there's a phenomenal commercial opportunity here somebody should develop this and make it available to you know a very significant percentage of the workforce uh and the other area I think is is education in some sectors uh the divorce rate is six times higher uh in the night shift compared to the day shift and six six times so what we should be providing is education not only for the individual who's doing the night shift so they're aware of some of the consequences but so that the people they live with also understand that they're not turning into monsters but this is a kind of the biological consequence of driving your biology outside of its normal range um and one other area which I think is worth trying is that we talked about this great diversity of chronotype whether you're a morning type or an evening type across the population well wouldn't it be smart to chronotype your Workforce so that for example the late types did the later shift and the morning types did the morning shift what you want to avoid of course is putting a late type onto a morning shift which is a is a really bad idea so uh you know as I say we've got to be pragmatic but I think there are things that we can do now to mitigate some of these problems we don't want to be too scary but um I can't stop thinking about that as a doctor myself that 57% figure yeah I have told this story I think at least twice on this podcast where when I was a sh a senior house officer so I think second or third year after qualifying after a what would it have been probably a 36 hour shift certainly between 30 and 36 hours I properly fell asleep on the M60 and traffic um thankfully I I think I fell asleep in a traffic jam and then I was only woken up by horns because the jam had you know moved on so you know it could have been a lot worse yes right this is scary because there are people around the country around the world right now who are vulnerable of dying as a consequence of their jobs that sounds extreme I don't think what I've just said is Extreme based upon what I'm reading and you you mentioned juicy of care for employers yes surely this should have been put in place yesterday like is it justifiable for people in shift work to be getting in a car now where does the culpability like what if they have an accident is it is that personal responsibility or is it no but my my employer didn't do anything or and of course this comes into finance and expenses but providing taxes well that's what the Royal Perth hospital at least when I was visiting Western Australia would actually do they would actually provide taxis to get people home yeah and I know there's an expense thing here but we're talking about lives here not just that individual's Liv so yeah that really that really hits home big time and and you know there's a very poignant description in the book of a police officer um who contacted me actually several years ago saying what can we do you know I just had a friend who after the night shift fell asleep at the wheel and drove his car into a tree and was killed outright um and nobody's warning us that this is going on and that's part of the educational piece because I think if people realized of the danger of doing this they'd think twice about it um and and try and get some something else in place I mean maybe we should be making sure that there's I don't know a somewhere to sleep um uh uh uh after the night shift so you weren't driving home chronically tired you know it's these sorts of things that that we need to think about this there are again we're not going to cure it but we can mitigate some of the problems and it's not rocket science it's it's lwh hanging fruit that we could Institute now across the workforce and make a difference I don't know when my behavior around this starts is to change but I'm pretty diligent these days over when our drive now now I don't need to drive much anymore for work I remember in one of the practices I used to work at you know there was a probably 45 minutes to an hour commute each way aut Theo way and depending on traffic conditions etc etc and I appreciate not everyone is in a position to make active decisions depends on work finances all kinds of things but when I'm weighing up how to get somewhere and whether to take my car or not how tired I'm going to be absolute plays in my decision making and I think you know as I think about it Russell I think one of the first times it really struck me probably 2015 2016 I was making a documentary for BBC 1 I don't think this but actually aired in the program at the end but is it in Guilford where is the uh driving simulators I think so yes I think what what happened I can't remember the exact ins and outs but one of the participants yeah we put them in the simulator and we watched them Drive and then we compared it with one night sleep deprivation and then alcohol yeah and it was noticeable after sleep deprivation it's just like you said with that research it was worse than when they'd been drinking y I was like wait a minute that's just fatigue and their their reaction time to things popping up in the simulator to when they press the break was significantly increased so I think that possibly has played into my head for many years about that um number two I think I think Point here is that you you bring it this ter micro sleeps right number one what is a micro sleep and number two I've heard you say before think about these microsleeps that you don't know they're going to happen yeah yeah right so so can you speak to that a little bit so it's it's really so microsleep is essentially an uncontrollable and an unpredictable episode of sleep and so you can be going along and you'll just fall asleep and of course that's extremely dangerous if you're if you're driving um and uh so people think they're okay and then they could just sort of have a have a micro sleep and then a crash or or or or whatever um and it's it's frightening because so many people say oh yeah you know I've had one of those I was sort of nodding and then I realized I was sort of in the next Lane and but for the grace of God you know you would be killed or you would have killed somebody else you mentioned in your book all these things what chob the Chino nuclear disaster was it Selby crash and Air India like You' mentioned all this stuff can you maybe speak one of the one of the really interesting ones I think was the the Air India flight where where the pilot was was Landing the aircraft and then fell uncontrollably asleep and the plane hit the deck um with a huge loss of life now how do we know he fell asleep because you could hear snoring in the cockit recorder and you know this is not something that he would have wanted to do but and it and it sort of really illustrates the the sort of the the fact that you have no control over these micros sleeps but if you're chronically tired that's what's going to happen and you know the Exon V's oil tanker that hit the reef off the coast of Alaska now everybody says oh it's cuz the captain was drunk well yes he was drunk and he was asleep in his cabin and it was a chronically tired inexperienced individual and they were telling him turn the ship you're going to hit the reef but he couldn't process the information cuz he was so tired and it's a really good illustration again of one's chronic tness prevents you from processing information accurately and you know we've sort of touched on this but this is what's so dangerous cu the tired brain is so tired it can't detect how tired it is and we can fool and we can fool ourselves that we're okay whereas we're not Russell I want to just ask you your view on my interpretation of my dad's working life I know from Rec search you've written a beautiful section on it in your new book about the impacts that sleep deprivation has on the immune system yeah and all kinds of other biological processes in the body my dads at the age of 57 got lupus now it's very unusual for an Asian man an Asian man who is Slim it's it's not the profile it's normally Caucasian women 30s or 40s that typically of course there's always variation here now for many years I cared for my dad until he died uh n and a half years ago and I didn't know then what I know now since his death but I am convinced I I have a deep knowing that my dad's lifestyle gave him lupus now I'm not asking you to say yes or no on that I just want to share with you some aspects of his lifestyle and I'd be interested your perspective my dad slept three nights a week for 30 years so he'd work his day job as a consultant maner War infirmary but he' come home he'd get ready and then for four nights a week Carl would pick him up and he'd be doing gy house calls all night so he'd be out all night he'd arrive again at 7 7:15 in the morning get ready then drive through traic andan and work so for 30 years he only slept for three nights a week so that is sleep deprivation I would say at a hyper extreme level he was chronically stressed of course I hear what you say about empathy and I think about Mom and Dad's Rouse yeah um and yes you need a genetic susceptibility for autoimmune disease but I believe my dad had that genetic susceptability I know he did because I've I've done my genetic I've done some of my testing and I know I have a predisposition as well to certain things if the environmental conditions are right my dad had chronic sleep deprivation chronic stress something maybe out with your expertise perhaps is I think my dad was very unhappy and had a lot of unexpressed emotions and anger about the state of his life I've spoken to Dr Gabel mate a physician about the the link between unexpressed emotion and also immune disease so I'm not necessarily asking you to comment on that but from what I've shared and from what you know about the immune system and sleep deprivation impacts do you have any comments at all yeah I I mean I think it's worth bearing in mind that for our biology to work you need the right stuff the right concentration delivered to the right tissues and organs at the right time of day and of course our Cadian and sleep wake systems do that so if you disrupt them you have a whole bunch of vulnerable points where things could fall apart sorry interrupt if you are enjoying this content there's loads more just like it on my channel so please do take a moment to press subscribe hit the notification Bell and now back to the conversation and so if you have a genetic susceptibility then the disrupted biology will will play to that that problem and so I wouldn't be at all surprised if there was an element of sleep disruption did your father show any signs of dementia later in in life it's really hard because he da was on dialysis for 15 years and all kinds of medications but yeah I'd probably say so little bits yeah no formal diagnosis but if I think back now possibly probably yeah and some very interesting uh data is showing that massive sleep weight disruption in the middle years can increase your risk of dementia uh in later years what do middle years mean um so so your your sort of 40s 50s um your your Peak working period we know where we think of our businessmen you know having incredibly shortened um sleep periods and it's it's been well known it's been documented but a mechanism has not been clear until relatively recently or a potential mechanism and that's this newly discovered thing which is the glymphatic system this sort of um clearance system within the brain and whilst we're asleep um there's a whole bunch of toxic stuff that is wrapped out and disposed of not least beter ameloid yeah and just one night of No Sleep has been shown to increase betoid deposition within the brain and increase the concentration in the cerebral spinal fluid so you know there's a there's a very tangible link between sleep disruption in the middle years and and a mechanism that could could predispose to Dementia in in later years and I think we're going to find increasingly these sorts of connections I mean what we know about the immune system is that it's it's turned up or at least the Adaptive immune system is turned up during the day when we're most likely to encounter people with bugs or bugs in the environment and then turn down at night and again a really interesting question is why why do you have the immune system on full kilter all the time and that's of course because if you did you increase the chances of an autoimmune response yeah and so you know disruption of these systems leads to lots of different Ripple through effects yeah there was something in the book I found fascinating about our skin permeability changes throughout the day could you speak to that perhaps yeah I mean so so at night um it's it's a bit more porous um and we're losing as a result we're losing water and so also it becomes itchier and so we're more likely to scratch our skin at night and you know exacerbated by psoriasis and and dermatitis and things and so the skin is an incredibly effective barrier keeping bugs out and that's why the main root of of infection is the lungs or but but but but if but the skin is again trying to Slough off these old cells um and presumably the bacteria with them and in a sense sort of cleanse itself but it increases the vulnerability to infection does it at that time of day of course because we're far less likely to encounter bugs at that particular time yeah there was also this fascinating bit of research you shared where I think if if we get cut or have a scar how well it will heal or how quickly it will heal depends on whether it was done in the morning or the evening I found that fascinating yes it is you know and of course um uh more effective healing during the day than than at night yeah yeah this relationship between midlife sleep deprivation so in our 40s and 50s and dementia later on is really something just to pause on perhaps because I'm in my early 40s um perhaps cuz I know many listeners and viewers are but there is this tendency I think across Society think we can keep pushing yeah we can keep pushing we'll get away with it we'll be okay now I've seen first on with my dad yes it was quite extreme but nonetheless I see that pattern I've seen it in myself before I've seen it in a lot of my patients and a lot of my friends you can't keep pushing your biology and not expect a consequence at some point so I I just wanted to highlight that point and then I want to you know you mentioned sleep and dementia I know you've done a lot of research on the relationship between sleep and mental health problems yes and I'd love to just talk about this a little bit you know is it sleep deprivation that's causing mental health problems is it mental health problems that's causing sleep deprivation or like most things is it a bit of both well I think this is really important and I got into this because I was um in a elevator with a psychiatrist and he said to me oh yeah you work on on sleep and stuff I said so kind of um and um he said well of course my patients with schizophrenia um they have terrible sleep patterns that's because they don't have a job so they get up late uh miss my clinic and are socially isolated and so don't have friends and I just thought at the time that doesn't make any sense at all to me and so we we started um and Katarina wolf was one of my colleagues um who was very much involved in this to look at sleep weight patterns in individuals with a diagnosis of schizophrenia uh same number of individuals age matched who unemployed and working healthy controls and the patents you saw in schizophrenia were some of the most extraordinary observations I've ever made in my career these weren't just sort of kindly mildly disrupted these rhythms were absolutely smashed in everyone we have looked at um and so that stuck in my mind and then with an increasing understanding of the mechanisms that generate sleep and Cadian rhythms so essentially the Sleep the Consciousness sleep flip involves a realignment of every brain neurotransmitter system and an interaction between multiple brain structur so with these two sort of observations we thought well hang on why do you always find sleep weight disruption and mental health Associated and and of course you see it in bipolar you see it in depression you see it everywhere and we came up with a model which was perhaps at the core within the brain there are overlapping neural circuits and neurotransmitter Pathways between stable sleep and stable mental health so if you're predisposed to mental health problems let's say there's a change in a a neurotransmitter dopamine serotonin that nudges you towards a mental health crisis but it's going to have a parallel impact upon the sleep wake systems at some level because they also draw from those neurotransmitter systems and so we then tested that hypothesis and so genes which have been linked to human schizophrenia when mutated in a mouse um uh not only showed weird behavioral patterns uh but also smashed sleep wake Cycles so now there's an incredible body of evidence for that mechanistic overlap between mental health circuits and sleep circuits but it's of course much more complicated than that because the disrupted sleep via its impact upon um psychosocial Health um one's one's ability to process information that negative salience and of course the sort of physiological disruption could uh exacerbate the extent to which you're experiencing mental health problems and of course the mental health problems will feed back and make the Sleep worse and so you can very rapidly go from sort of this this sort of overlap at the middle we know there's a genetic predisposition to certain mental health conditions but it can then amplify massively as a result of these positive feedback loops the mental health making the Sleep worse the Sleep making the mental health worse so you can exaggerate it completely so we then thought well hang on if we try to stabilize sleep wake in individuals exhibiting mental health problems will we reduce the severity of those mental health problems so working with Dan Freeman and Colin espie big paper was published a few years ago in the lanset uh which showed that if you can even partially stabilize the sleep wake in individuals you can reduce levels of paranoia and hallucinatory experiences so I think we can we can think of the sleep wake systems as being a new therapeutic Target for mental health now what's fascinating for me is that we've known about the association between mental health problems and and sleep disruption back at you know kin's time in the 1880s he talked about it way before the introduction of anti psychotics and and all of the other sort of um issues and so it has a long history and uh of course the life expectancy of individuals with severe mental health uh is hugely reduced and they all report you what do they report um uh sort of coronary heart disease obesity type 2 diabetes all of these major health issues dismissed as a as a byproduct of the antipsychotics but actually it's a major contributing factor to that will be the the poor sleep and it's never addressed yeah um and so this I'm I'm hoping that this will will will also provide a change in our mindset to these extraordinarily vulnerable individuals and to take their sleep weight disruption seriously because we have empirical evidence that even partial stabilization can reduce the severity of um those symptoms you're effectively saying bipolar or depression or anxiety right instead of just accepting it as oh yes people with these conditions don't sleep well it's like well hold on a minute what if we go straight in and give sleep education or sleep C or whatever therapy we might deem appropriate and then if you think about research I mean I remember reading a paper Russell where it showed that maybe if you go from 8 hours a night to 5 hours a night your a migdala the emotional part of your brain may be up to 50% more reactive yeah I think well that's kind of anxiety you know if you're amigdala is on high alert you're anxious yes and sleep deprivation by itself will make you anxious yeah so before we go to anti- anxiety medications or exactly it's like why don't we tackle the sleep why don't we at least try to and and it's because the failure to educate our our general practitioners and indeed are the entire um you know do doctor and nurse Community um it's just not part of the curriculum and In fairness um it's only fairly recently that this stuff has become really clear um and and again that was part of the the reason for for for writing you know lifetime because wanting to make it accessible to you know not only medical practitioners but everybody so we can take some ownership of this of this field this critically important field I mean this is really quite profound because what we're talking about here is sleep as therapy yes I mean this was really of shown shown to me when we working on a project with with um guy Goodwin who's a psychiatrist at Oxford and he was able to identify individuals as a result of family history and questionnaires whether they were at high risk or low risk of developing bipolar so these are young young individuals in that teens usually and what was absolutely fascinating is the Sleep weake patterns of those at low risk were perfectly normal but all of those who were at high risk were already showing a disrupted sleep weight pattern prior to any clinical diagnosis of bipolar now if we can use this as an early marker and then of course in therapy the earlier we we know something's going to go wrong the earlier the chance of an intervention so wouldn't it be amazing if we could identify those individual at risk we could Institute sleep wake stabilization protocols that may either delay the onset of these conditions or knock the brain into a different developmental trajectory whereby it won't necessarily go uh inevitably towards that uh condition so again I think there's you know we we're we're just sort of unmasking all this incredibly important stuff that could have a Major Impact upon health and well-being uh as in the coming decades Let's Talk About Sex and sleep yeah um you write a little bit about it of course it's a topic of huge interest to many people yeah and I guess there's two facets to it the way I see it one is to do with fertility right there is an ideal time to have sex from a fertility standpoint so I think it'd be great to talk about that yeah but then I think also the relationship between sex and s the onset of sleep I think is also really interesting so um in whatever way you want to maybe start to unpack that for again this was something that I wasn't particularly familiar with until I did the research for the book because I'm often asked these questions in public lectures what was absolutely striking is that every element in the regulation of the female menstrual cycle involves a circadian clock whether it's the timed release of hormones neuro hormones in the hypothalamus whether it's the pituitary gland or whether it's the receptors in the ovary for example responding to those those those hormones and so you've got for example very strong evidence that disruption of the menstrual cycle is much worse in night shift workers um the chances of miscarriage is higher in night shift workers is not hugely significant but it is significant and you find that in the airline industry either Pilots or flight attendants have fertility problems so there's there's clearly a relationship between the Cadian system uh and the menstrual cycle to produce this extra exquisitly timed ovulation and the release of the release of the egg and it's been shown that sperm needs to be in the reproductive tract in the fallopian tube around about 2 to three days prior to ovulation to have the greatest chances of success so there's there's there's there's that there's the the cadan system interacting with the hormones that drive the menstrual cycle which is and and that precise window and and and that was really fascinating then they got this study of suggesting well it doesn't really matter you know humans don't have any real discrimination they just do it whenever they want to do it um and then there's this whole literature on the fact that in fact our behavior is subtly altered so that actually um during that sort of pre-ovulatory window men are less discriminating of women um and are much more likely to seek out you know copat experiences um and females are much more discriminative they're far more likely to have an affair during that that window and they look for male they're more interested in male features so for example um a deeper voice a stronger jawline all that sort I mean stuff that we never really think about but but there is there is that still biology you know underpinning it wow so so yeah um but also um male fertility uh seems to peak in the morning testosterone Rises and has a you know morning Peak and that's where sperm motility is uh at its peak and anyway I mentioned this I think on the Chris Evans uh breakfast show and I got this email uh several a month or so later um from a couple of young Medics who said um you know we've been trying for the last two years um to um conceive and uh um we know as Medics we thought we tried everything but we forgotten Cadian rhythms so we started um and their words not mine started doing it in the morning and the first and the first time we did it you know my my partner got pregnant um now I mean an N of one is an N of one so you can make of it what you will but I was actually thrilled that that that bit of biology had been translated congratulations even that that that line we forgot about Cadian rhythms I'm not surprised like we didn't learn anything about Cadian rers and medical school I don't think they still do right this is a you know massive massive issue yeah so regarding fertility super super interesting I'm sure that's very relevant to many people listening like who are actively trying to conceive it could be something that has practical value for them or people can share it with people who they also know who are struggling uh that might be helpful in terms of we mentioned the problems with sleep deprivation and um you've written a section in the book how the timing of sex could potentially help people with sleep yeah I mean I think anecdotally um there reports that you know sex relaxes individuals and they're more likely to fall asleep and and there are now some studies suggesting that um there are there are hormones that are that are released which actually promote sleepiness and so yes uh consensual sex of course um it has been shown to promote sleep yeah and also masturbation as well you have once said that many people don't have a sleep problem they've got a stress problem yep and I guess sex intimacy you know switching off it all kind of feeds into that a little bit doesn't it absolutely yes and and and the bonding a following sex um uh you know relaxes individuals and brings them closer together I I I think that one thing that's very important to distinguish is fatigue from sleepiness um sleepiness is cured by Sleep fatigue is this overwhelming chronic tiredness that even given the ability to sleep longer doesn't go away and it's very important that people distinguish between the two because fatigue as you know um is indicative of some underlying health problem and I spoke to somebody fairly recently really fascinating and this is um a really high-powered individual very very active but she has an immune issue and so is chronically fatigued and so she can't get done what she wants to do during the day so she'll fall asleep fine and then she'll wake up in the middle of the night and we should talk about that because that's perfectly normal to wake up in the middle of the night and most of us fall back to sleep again or are awake for a short time then fall back to sleep again but because of her um stress because she couldn't do what she wanted to do she couldn't fall back to sleep again and so uh this was a really interesting so the fatigue was was not allowing her to do what she wanted to do which meant that she was immensely stressed which meant that it was screwing up her her sleep problems and so uh yeah I think that so many instance of I think stress is is one of the major issues in poor sleep and as we've just said it's not a sleep problem it's a it's a stress problem and that's why sort of winding down um towards the end of the day leaving work at home if you possibly can um and doing something different whether it's going to the gym whether it's doing whatever is so important and that's of course been the huge problem um during the covid epidemic where people's works space and and home space were the same and that's probably part of the reason why sleep um has been reported to be worse in in certain sectors yeah I mean you spoke before about various sense and what people associate with sleep and you know we know the brain is an associative organ and so if you are sitting with your laptop doing your work emails in bed what does your brain associate with bed in the bedroom precisely and of course so many bedrooms became studies yeah and and I understand that it depends on your space and it's not it's not a criticism it's just more a an explanation it's more an explanation this can be problematic I think you know I mentioned the the the the low Lux Amber buls that I have in my bedside lamps and I think there's a biological explanation in terms of the lower Lux it's not pushing my Cadian Rhythm back my clocks back sure but actually and critically reducing your alertness which is probably the main main factor okay so it's reducing my alertness because of the lower light exactly higher the light greater the alertness and the more more difficulties to get off to sleep okay so that's fascinating and I guess speaks to well so many bathroom mirrors are yes like bathrooms are full of these bright LEDs right so what do people do before all that well I know I mean it's I think it's absolutely spectacularly ironic that what's the last thing we do before we go to bed we stand in the most brightly lit room of the house which is the bathroom and then we look into an illuminated mirror as we clean our teeth um and you know we talked about a an investment opportunity in developing night shift food another uh perfect investment opportunity is developing a bathroom mirror which has bright alerting light in the morning and you switch it to the evening which is dimmer less alerting light um in in in the evening yeah I mean it's simple yeah the technology is there to do it absolutely yeah so that's that's something else we can think about what how you know what sort of light are we exposed to there but speaking about these bedside lamps I think also as well as the biological explanation I think there's also I guess something behavioral about them for me in terms of it's it signals to me oh it's now evening time it's rest time it's not stimulation time do you know what I mean so I think winding down we assume that we can go from a fully conscious State you know going the gear analogy you know going from first gear to fifth gear you can't do it um you have to do it through stages and again winding down from the Wake state to The Sleep State requires an adjustment um and whether that's as you were saying you you enjoy reading um some novel uh under relatively dim light before going to bed some people listen to music or some something else that they find relaxing and it's and it's it's adopting those behaviors that make the transition easier and again it's it's it's as you were saying it's the brain knows what's coming next and what's coming next is sleep and so it can prepare itself it's what we do with our kids right we give them a routine you know we don't we read a story we read a story we we don't as I often say us we don't give them a ton of sugar put the lights on bright speak loudly no no we do the opposite of all those things but as adults kind of think we can somehow until their favorite uncle visits you exactly we think we can override them but we can't oh Russell I can speak to you for hours as we come towards the end of this conversation few things I wanted to briefly cover if possible sleep trackers yeah um any any view on sleep trackers well I think we should Define where they could be useful so um most sleep trackers uh if you use them to determine roughly when you went to sleep um how many times you woke up in the night for example and when you finally woke up so your sleep timing your sleep duration and your sleep fragmentation that's a tried and tested technology and it's what we use in the lab the problem is that most of the The Trackers that people wear these days try and do more than that they say oh you've had lots of good deep sleep or you've haven't had enough REM sleep and and for that they're completely useless and um they can they can generate huge anxiety um so so I spoke to an individual uh again before lockdown who said I'm not getting I'm not getting enough slow way sleep I'm really anxious about it in fact what I do I set my alarm clock for 4:00 in the morning wake my myself up to to find out how much slow wave sleep I've had I mean that's the kind of level of anxiety that these things um are developing and in fact so so what what does it really tell us if we've had lots of slow wave or lots of REM sleep we don't really know and the algorithms first of all are not very good at detecting that um and they've been largely worked out for a bunch of 20 year olds in California um uh and and of course our sleep changes hugely as we age um and they're not going to work for somebody in their 70s or indeed you know somebody younger um so until we got you know really sophisticated artificial intelligence you know plotting the extracting information to get sleep phase they're not they're not accurate and the other the other problem I have is so what you know do we really know what slowo sleep is all about well sort of I mean we know that if people are selectively deprived of slow wave sleep their memory isn't as good and their problem solving isn't as good and if people are selectively deprived of REM sleep then their emotional proess they show a bit more anxiety during the day but in a sense we we don't really know and and so I do get very frustrated because we become as a society finally more sensitive to the importance of sleep but what's happened is that a large sector have become very anxious about their sleep yeah and you know there's these sort of sergeant majors screaming you've got to get eight hours you've got to do this you can't do that and we have to Define what works for us and and in fact so many people think is the sleep is what you get but actually it's a highly Dynamic bit of our biology and we have the ability to work with it and optimize it and I think that's that's something that I and and and the Sleep apps you know drive us in the opposite direction so I I get a bit worried I mean you know in principle good idea because uh if you it's like losing weight if you weigh yourself every morning um uh and you see you've lost weight that will reinforce your changed eating behavior and if you wanted to get longer sleep or different timing of sleep as we've kind of touched on it would be useful metric to say yes well that change Behavior has worked so you know getting that more Morning Light meant I did go to bed to bed earlier and and I've got up earlier so in principle they could be useful but it's worth bearing in mind none of the um the sleep federations indorse any of the commercially available devices and none of them are FDA approved yeah so we're long way for for them being I would say useful yeah thank you for that that was very very clear I mean that weight loss analogy if we take it one step further yes if you see every day your weight is going down let's say you are tracking that and you think that's the Reas things ATT track sure it can motivate Behavior but on that one day where it goes up and I I read a study once which said that actually our weights can vary I think 3 to10 in any given day I think it said maybe 3 to 5 just from fluid and all kinds of other stuff I thought well actually it can have a really Toxic effect when you're you're making all the right changes for your health and maybe for excess weight but actually one day it happens to go the wrong way yeah good point what's the point yeah what's the point well I think it could be problematic and I have a real concern over trackers in general I'm not at all saying they can't be useful for some people I understand it probably depends on personality type a little bit in says of what you do with that dat I do have a sleep tracker I don't think I've used it for about 6 months um it was considered one of the good ones and I have no problem with it you know it was useful there was certain things that I felt it helped me understand which is if I eat late it appears to really have an impact on various things but I kind of learned what I needed to learn from it and one day Russell I remember waking up feeling pretty good and I looked at my sleep score and it was rubbish and then my mind starts to play tricks on me I was like oh and then I thought God am I starting to feel tired like because I'm tired or because what I've just seen I thought you know what screw this I'm not I don't need to use this anymore I need to tune into myself and I personally I've seen even with blood pressure monitors I've seen patients over the years tie themselves up in knots and have health anxiety so I guess I would just urge a note of caution as well for people I think that's absolutely right and we've talked about how do you know if you're getting enough sleep what the factors are that's the most important thing and these are questions we can answer for ourselves without the need of of a health health tracker good good good friend of mine Ken Wright who's um University of Colorado um he starts his um his class and you know it's a large number of students with uh who here has ever used a sleep tracker and you know essentially the whole class sort of put their hand up and they said who now is is using one routinely and about three hand that go up and you know these are smart people they learn pretty quickly that these devices just don't work um and you as you've discovered you you you you you you embrace the knowledge from your own personal experiences yeah yeah to be a human and to really The Experience what that means um just very quickly a lot of people will often say about light exposure well what about let's say Scandinavia for example uh I guess that's top of mine because I've been recently the hotel in which I stayed had pretty poor blackout blinds and so I woke up in the night and then I thought it was morning and I looked to my watch it was it's 3:00 a.m. it was bright at 3:00 a.m. how have people in northern hemisphere countries or or other countries where there are these wildly different day and night cycles have they evolved to that have they adapted to that do we know well the short answer is no but let me tell you about a group of animals that have and um uh from the University of trumo they've looked at Arctic reindeer and during the two months of constant light they turn their biological clocks off and during the two months of constant dark they turn their clocks off they have no adaptive value there is no day night cycle um and in fact during the winter months these reindeer uh feed whenever the weather conditions permit and during the summer of course they have to feed constantly to put on enough fat to survive the winter so there are instances where clocks have been turned off because they have no adaptive value what about humans well we've of course been there for a very well the Europeans who've moved into those those um those those places have have shown no signs of adaptation in fact in in tromo a family will get up um and then they'll go in in Winter for example into a room where there's there's artificial light so they'll get that morning Photon shower um and so so they can try and stabilize and and they use very effect effective blackout curtains now what's going on with those peoples the native peoples who've been there for 30 40,000 years isn't clear yeah um and it may well be that there has been some adaptation but where we don't know Russell my brain is going so fast in so many different directions um out of respect to your time I'm going to stop iring questions at you and I hope I can persuade you at some point in the future for a part two um to finish off this conversation on a upbeat note um for people who feel inspired to prioritize their sleep to get on top of their sleep to basically go you know what maybe it was a bit about being in your 40s to 50s and not pushing it whatever it might have been that connected with them this podcast is called feel better live more when we feel better in ourselves we get more out of our lives lives of course when we're going to sleep better we're going to get more out of every aspect of our lives so do you have any final words of wisdom advice practical whatever it might be to lead my listeners with I mean I I think the key thing for me is that you know sleep is like Sho size um one size does not fit all and we as individuals need to work out what's best for us um because there's huge individual variation and our sleep will change so good example would be waking up in the middle of the night um so what's happened uh is that our uh our sleep episode has been compressed and so we we tend to not wake up in the middle of the night but under uh in societies where there's no electric light and indeed from the literature uh we know our sleep patterns in the recent past were very different so literature from the pre-industrial age talks about I had a wonderful first sleep um or uh and sleep was biphasic uh going to sleep waking up then going back to sleep again or indeed polyphasic which is uh you know several periods of of waking up and because we don't know that when people wake up in the middle of the night they think oh my goodness that's it I'm never going to get back to sleep again I'm as I start doing my emails now and um start drinking coffee and and and the key thing is that waking up in the middle of the night need not mean the end of sleep in fact that polyphasic or basic sleep pattern is what all mammals experience and so this again single block of of of Consolidated one block of sleep is not the natural state that is such an important message isn't it the amount of people who feel bad that they wake up I I know they have questions that get fired at me about this you know is it okay and you're you're clearly saying no this is not only okay it's very very normal I guess this speaks to the problems with having our smartphones in our room just looping back I don't know you mentioned not in this conversation I've heard you say about your relationship with your blackberry when you were in Australia and actually had to ultimately leave it in your lab yes I I have I I'm just sort of I think they used to be called crack Brees um and and yeah I was in Australia and so I would do my Australian uh emails on on the blackbery then of course the European ones would come in and then the North American so so if you're jet LED um and and I remember you know this this this red blinking light those those who had a Blackberry and I was so weak I I I could not first of all it was by the bed and of course I then moved it very quickly to the room next door and that was hopeless cuz I'd wake up and then I'd go next door and so um I left it in the lab and of course as a result I got much better sleep yeah because when you wake up if you're not getting your mind actively engaged back into work you a lot of us probably don't realize that we may well have fallen asleep again had we not done that that's what most of us do in fact you know we go through cycles of REM and non-re and we naturally wake from from REM sleep and then we fall back to sleep again without even noticing it now that wakeup period can be you know a few seconds so you don't notice it or it may be 30 minutes but the chances are you will go back to sleep as long as you stay relaxed you keep the lights low and you do something that is not alerting the brain and as I say because we haven't ever passed this information on you know people don't know when they think oh my goodness that's the end of sleep I'm sleeping terribly and in fact if you stay calm um it's fine the other thing another tip I guess would be illuminated alarm clocks cuz many people clockwatch they'll wake up and then they think oh my god I've only got two hours before the alarm goes off it doesn't matter you know if you go back to sleep you know and you have that additional two hours or half an hour again it doesn't matter so if you have an aluminated clock put some tape over the front of it the only thing that matters I guess is the alarm not how long you've got before the alarm goes off which brings us back to the start of the conversation which is alarm clocks stop the single most behavioral single most important behavioral experience we have if that conversation resonated with you here is another incredibly powerful one digestive issues mental focus issues exacerbation of every major psychiatric disorder from OCD to ADHD is closely associated with disruptions in circadian clock function the foundational practice that I truly believe every person should do every day is