Sleep, Circadian Neuroscience & Human Performance

In this episode, Martin and Jonpaul talk to Professor Russell Foster, a world-renowned expert on sleep & circadian rhythms. They discuss the importance of sleep and circadian rhythms for human performance; how the circadian system provides the time structure for life, optimising physiology and behavior; and highlight some evidence-based strategies for enhancing sleep quality and quantity.  

Get the episode here

Guest, Cast & Crew

Russell Foster is Professor of Circadian Neuroscience, director of the Sir Jules Thorn Sleep and Circadian Neuroscience Institute and the head of The Nuffield Laboratory of Ophthalmology at the University of Oxford. Russell’s research interests span visual and circadian neurobiology, focusing particularly on the mechanisms by which light regulates circadian rhythms. 

Russell has published hundreds of peer-reviewed articles and books, including his recent book, ‘Life Time: the New Science of the Body Clock and How It Can Revolutionize Your Sleep and Health’.  

Hosted by Martin Jones & Jonpaul Nevin https://www.ophp.co.uk 

Edited by Bess Manley

Produced by WavellRoom https://wavellroom.com/audio/ 

Resources

• Sir Jules Thorn Sleep & Circadian Neuroscience Institute https://www.scni.ox.ac.uk

• Nuffield Department of Clinical Neurosciences, University of Oxford https://www.ndcn.ox.ac.uk/team/russell-foster 
• ‘Life Time: the New Science of the Body Clock and How It Can Revolutionize Your Sleep and Health’ by Russell Foster https://www.pemberleybooks.com/product/the-ecology-of-vision/34916/ 
• ‘The Ecology of Vision’ by John Lythgoe
• ‘Blitzed’ by Norman Ohler 

If you’re enjoying this content, please like and subscribe so we can keep improving. And remember to visit WavellRoom.com for their latest articles, podcasts and newsletters. 

Chapters

00:28 Journey into Circadian Rhythm Research

01:56 Understanding Circadian Rhythms

03:43 Consequences of Sleep Deprivation

09:25 Mental Health and Sleep

15:16 Shift Work and Health Impacts

25:45 The Role of Light in Circadian Rhythms

36:38 Understanding HPO and Sleep

37:22 Strategies for Better Sleep

37:46 The Role of Light and Relaxation

39:06 Avoiding Sleep Disruptors

40:48 The Importance of Routine and Naps

43:42 Challenges of Night Shift Work

47:17 Impact of Light on Sleep

58:55 Food and Circadian Rhythms

Up Next

Next week, we’re delighted to welcome consultant psychiatrist Professor Steve Peters, to discuss his work in optimising human performance.  From the NHS to elite sport, Steve helps people to understand how the mind works, gain insight into their own minds, and develop the skills to optimize individual performance and quality of life. We discuss his famous chimp model, imposter syndrome and the antecedents of high performance. 

Transcript

[00:00:00] INTRO: Hello and welcome to the Optimizing Human Performance podcast. I’m Martin Jones, a Human Performance Specialist, Researcher and Educator. And I’m John Paul Nevin, a former Royal Armoury Physical Training Corps Instructor turned academic. Each week we talk to world leading experts about how to unlock the full potential of those who operate in high stress, high stakes environments.

We discuss the latest science, innovative strategies, practical wisdom and inspirational stories in the rapidly evolving world of human performance optimisation. The Optimising Human Performance podcast is produced in partnership with the Wavell Room and the Tactical Athlete Performance Centre at Buckinghamshire New University.

In this week’s episode we talk to Professor Russell Foster. Russell is a professor of circadian neuroscience, the director of the Sir Jules Thorne Sleep and Circadian Neuroscience Institute and the head of the Nuffield Laboratory of Ophthalmology at the University of Oxford. Russell’s research interests span visual and circadian neurobiology, focusing mainly on the mechanisms whereby light regulates circadian rhythms.

Russell has published hundreds of peer reviewed articles and books, including his recent book, Lifetime, the new science of the body clock and how it can revolutionize your sleep and health, which I highly recommend. JP and I talk to Professor Foster about the importance of sleep and circadian rhythms for human performance.

We uncover how the circadian system provides the time structure for life, optimizing physiology and behavior, and we highlight some evidence based strategies for enhancing sleep quality and quantity. 

[00:01:36] JP: Russell, welcome to the Optimizing Human Performance podcast. How are you today?

[00:01:40] Russell: I’m very JP.

[00:01:42] JP: we’re really chuffed to have you on the podcast today. big fan of your work and all your various outputs and readings which I’ve came across over the years. But it would be really good just to get started.

If you could just introduce yourself and just provide our listeners with an overview of your career. Sure. Highlighting your current role and how you came to be involved in the area of circadian rhythm research.

[00:02:04] Russell: So, JP, how long have we got? uh, so I start, I started uh, very unremarkable, in fact, in remedial classes at school, because I kind of lived in my own little bubble and I went to university. Thinking I’d become a marine biologist because I was a good swimmer, a competitive swimmer, and I love biology, so, duh, you know, become a marine biologist.

And then I discovered physiology in my second year and realized that excitement of trying to understand fundamental mechanisms and that led into how And then a much broader interest in trying to understand the mechanisms that generate sleep in circadian rhythms. And particularly how they’re regulated and what happens when these systems fail as a result of specific conditions or as a result of societal impact, and then critically developing and targeted interventions to mitigate some of the problems of sleep and circadian rhythm disruption.

And of course, then disseminating this information to the broadest possible audience. So, yeah, that’s sort of it in a nutshell.

[00:03:09] Martin: Fantastic. been interested in sleep and circadian rhythm research for a while. It was interesting to me as a young sport scientist that we never talked about sleep. We never talked about biological rhythms, circadian rhythms.

And as I learned more about these areas of research, it, became almost confusing that I’d never been taught the fundamental importance of sleep as a. biological rhythm, and other circadian rhythms.

But for the people listening who maybe have heard the word circadian rhythm, but maybe don’t know what it is, can you describe and explain what are we actually talking about when we’re talking about circadian rhythms?

[00:03:42] Russell: Yeah, well, if we, if we step back and we think about what biology is supposed to deliver, I mean, what it does is deliver, ideally, the right stuff at the right concentration to the right tissues and organs at the right time of day. And it’s the circadian system, which is this internal biological clock, this internal representation of a, day that provides the timing.

time structure for life. Why do we need it? Well, of course, we sit on a planet that revolves once every 24 hours or thereabouts. And of course it presents us with profoundly different environments. And we have to adapt to those different environments as has all life on the planet. And so what this clock does is anticipate the very demands of the rest activity cycle and then fine tune our physiology and behavior.

to those different demands so that we can optimize physiology and behavior. So during the day, of course, we’re active. So we have increased metabolic rate. We have greater efficiency of lung capacity and all that stuff. Whereas when we sleep, um, metabolism is slightly lower. And of course we’re in the sleep state.

Now, Really important, as I’m sure we’ll unpack, sleep is not the turning off of biology. It’s just a different state of biology. And, in fact, what we’ll hopefully discuss is that the quality of our sleep defines the quality of our wake state. And it’s this circadian system that provides the time structure for that incredibly important biology.

[00:05:12] Martin: Let’s dive into it now. Russell, tell me about sleep. What? A very broad question. Why sleep important?

[00:05:19] Russell: Oh, gosh. Well, We’ve defined why sleep is important largely because of what happens when we don’t get sleep. So if we kind of unpack three domains of where sleep is important, which is in our emotional, cognitive, and physiological health. So even a couple of days without sleep, you find Fluctuations in mood increase.

Irritability increases. Our ability to interact with others is certainly diminished with lack of sleep. Anxiety increases. loss of empathy. I think it’s so fascinating. Our ability to pick up the social signals, from others. We can’t actually read what other people, their emotions and what what they’re sort of doing.

risk taking and impulsivity is incredible. so normally, you know, you’d never sort of try and get through the traffic light before it turns red. You’d calm down and you’d stop in advance. but tiredness makes us unreflective things. Some really fascinating work has been on what’s called negative salience.

So, the tired brain remembers negative experiences Was it forgets the positive ones. So once hold world view when you’re tired is focused upon the negative rather than the positive. We’re much more inclined to drive the waking day if we’re tired with stimulants such as caffeine, and sugar rich drinks.

And then, of course. You’ve got to reverse that. And caffeine, of course, is extremely effective at increasing alertness. But caffeine can last in the body between five and nine hours. So, you know, coffee later in the day is going to delay sleep at nighttime. And so what people tend to do is either use alcohol, which is the most frequently used sedative, or sleeping tablets.

And the key thing about those sedatives is that they don’t provide a biological mimic for sleep. They actually sedate the brain. And so, in fact, they can make the situation worse. So if we move from sort of emotional responses go to cognitive responses, overall our cognition fails. Our ability to multitask.

What we’re good at when we’re fully rested is extracting from a whole mass of noise what’s relevant and what’s not. That fails or becomes diminished when we, are tired. Memory consolidation, one of the extraordinary things that we’ve discovered is that our ability to remember facts is hugely enhanced by a night of sleep.

But it’s not just facts. We’re actually processing information. A night of sleep has been shown to hugely increase our capacity to solve problems. Whilst we’re asleep, the brain is ticking over a problem. And I think we’ve all experienced this anecdotally. You wake up and think, oh yeah, that’s the answer.

And so that’s why sleep is so important in that domain. Communication skills, decision making skills, creativity and productivity, all affected by poor sleep. But if we then move to the domain of long term sleep and circadian rhythm disruption, after sort of 4, 5, up to 20 years of night shift work, for example, then we see some really important issues surfacing.

So, the tendency to fall asleep during the day, micro sleeps. So, interesting study a few years ago on junior doctors. 57 percent have reported either having a crash or near miss on the journey home after the night shift. We see high rates of cardiovascular disease, altered stress responses, which is probably underpinning a lot of this.

our biology is saying you should be asleep. We’re overriding that. biology by activating the stress axis. So we’re releasing cortisol, adrenaline, increasing heart rate, throwing glucose into the circulation, which of course can lead to metabolic problems such as diabetes and obesity. We also suppress the immune system with high levels of stress hormones.

So that is probably why long term night shift workers are more susceptible to infection, but also, importantly, cancer. It’s worth bearing in mind that the World Health Organization has now designated night shift workers a probable carcinogen because of the high rates of breast cancer, colorectal cancer that you see night shift nurses.

Then, of course, we go into the domains of depression and psychosis, where there’s an incredibly important link and then, also dementia, we’ve known for quite some time that poor sleep in the middle years is a risk factor to dementia.

for dementia later on. Now, I would never say that poor sleep is going to cause dementia, but if you’re on that sort of risk spectrum, then it will increase it. And the mechanism is fascinating. So whilst we are asleep, the brain is clearing toxins and one particular, toxin is a, is a misfolded, protein called beta amyloid, which builds up in the brain and is thought to underpin Alzheimer’s and dementia.

even one night of no sleep you can actually detect a slightly increased level of this misfolded protein within the cerebral spinal fluid the brain. So we now have mechanistic understanding of why poor sleep is a risk factor for dementia later on. So essentially, you know, why is sleep important?

Well it clearly defines our ability to function during the day. But it also. makes us human. I mean, in a sense, you know, our ability to solve problems, our ability to communicate, our sense of humor, all of those incredible faculties, massively diminished if we don’t get the sleep that we

[00:10:45] Martin: It was a broad question, very good answer. Very good. I’m sold.

[00:10:48] Russell: Well, probably a very long 

[00:10:50] Martin: I’m sold. I’m sold. If anyone’s listening to this podcast at midnight, turn it off and go to sleep. That’s probably a key message for that. But yeah, great answer. Thank you.

[00:11:00] JP: So Russell, obviously there’s a lot to unpack there and steering the focus more towards our Many of our audience are going to operate in what we call high stress, high stakes roles whereby. sleep and sleep deprivation is, at points, just a matter of fact, is what happens.

And from what you described there, we can certainly see that there’s obviously going to be an acute impact, but what, really stood out was when you mentioned that concept of negative salience and the potential downstream impact if someone’s exposed chronically in an environment where they’re consistently sleep deprived or they have poor quality sleep, there’s that.

Increase their susceptibility to mental health conditions, depression, potentially even post traumatic stress disorder.

[00:11:42] Russell: Well, absolutely. I mean, there’s, there’s several issues there. so I started to study human circadian sleep because of A strange encounter in a lift in a hospital in London and I was in the lift with a psychiatrist and this chap said to me, Oh, you work on sleep? 

And he said, Oh, well, my patients with schizophrenia have terrible sleep. That’s because they don’t have a job. So they go to bed late, get up late, miss my clinic and don’t, have any friends. And I thought that was such a stupid thing to say. It prompted me to team up with another. psychiatrist, and we looked at her patients with a diagnosis of schizophrenia, and we compared them with unemployed individuals and employed individuals, and what was so striking is that the unemployed were basically the same as the employed.

There was no massive, difference, but the people with schizophrenia, their rhythms were absolutely different. Absolutely smashed. when I saw these records emerging, was completely gobsmacked. and so that meant to sort of think about what’s the origin of sleep and circadian rhythm disruption and mental illness.

 And we produced a model, a very simple model, which is that at the core, there’s probably an overlap in the neural circuits in the brain, which are regulating normal mental health and normal sleep. Now, if you change a brain neurotransmitter that predisposes you to a mental health condition, it’s almost certainly going to have an impact on sleep at some level.

Because sleep itself is this sort of extraordinary flip flop between Consciousness and sleep. And there’s a complete realignment of all the brain neurochemistry. And so at the core, there’s going to be an overlap and to cut a long story short, we found lots of evidence for this.

So genes that have been linked to the sleep and circadian system have also been linked to mental health and vice versa. So there is that mechanism, but it’s more important than that because sleep and circadian rhythm disruption produces all of those. issues, cognitive, emotional, physiological, it’s going to exacerbate the mental health status and of course the mental health status is going to feed back and make the sleep and circadian rhythm disruption worse.

So you can have that sort of vulnerability and then move very rapidly to a pathological state because the poor sleep makes this psychiatric illness Worse, the psychiatric illness makes the sleep worse. So we, we reasoned, if we can stabilize sleep and circadian rhythm disruption in mental health, will we reduce the severity of symptoms?

And I was privileged to work with a psychiatrist here in Oxford, called Dan Freeman. And we were looking at individuals with poor sleep showing paranoia and hallucinatory experiences. And we used Colin Espie’s digital CBTI, cognitive behavioral therapy for insomnia, to partially improve the sleep of very large numbers of individuals, thousands of individuals.

And what was absolutely striking, Is that if you could reduce the level of insomnia You halved, in many cases, the paranoia and hallucinatory experiences, showing beautifully, really for the first time, that we can think about sleep as a therapeutic target for mental health conditions. And that’s now taken off.

and in many, branches of psychiatry now, people are using sleep. It was marginalized before. You know, so many people say, well, it’s lack of social structure, or it’s an artifact of the drugs people are on.

Now, the drugs may influence it, but they’re not causing the poor sleep and circadian rhythm disruption. And so it’s, it’s wonderful to see that in all domains. So for example, in depression, we now know that, a change in sleep wake patterns precedes a depressive episode. It is not the product of depression.

So you can use a change in the pattern of sleep as an early warning sign of depression. And a fantasy that I have is that, you could monitor individuals, their rest activity profile in the field, in the home environment. You could get a computer to alert you to the fact that the pattern has changed, you get on the telephone, how you’re doing, anything you need, do you want to come in and talk about it?

So you can preemptively deal with a depressive episode. And in the same way, we’ve done some work and this was by Guy Goodwin on, bipolar. And we looked at individuals who were at risk of developing bipolar, high risk or low risk. And what was fascinating, before any clinical diagnosis of bipolar, you were already seeing in sleep patterns.

does that mean though, we could then take those at risk individuals, trying to stabilize sleep, will that knock the brain into a different developmental trajectory. Will it delay the onset of these ferocious mental health conditions? So those links I think are increasingly being recognized and also as a therapeutic target.

I think it’s a very exciting time.

[00:16:46] JP: absolutely fascinating. So in regards to shift work, you mentioned that before, so especially night shifts. How does that sort of patterning impact upon not only the cognitive abilities of individuals who may operate in high stress roles, but what might be the potential long term consequences on their health?

So obviously we mentioned the psychological component, but what about the physiology?

[00:17:10] Russell: Oh, physiology. You know, you know, absolutely. So pretty much everything we touched on before your cardiovascular, your stress responses, your vulnerability to cancer, infection, metabolic abnormalities, psychosis, and depression, and of course, ultimately dementia. so I think the important, we need take into consideration is that the demands of the 24 7 society and night shift work are not going to go away.

you know, don’t do night shift a nonsense, 

[00:17:40] Martin: I need those Deliveroo drivers. they’re a 

[00:17:43] Russell: yeah. 

[00:17:44] Martin: at, uh, 11

[00:17:45] Russell: Well, well, 

[00:17:46] JP: Mate, we don’t get them in the

[00:17:47] Russell: well, we can, Martin, we can talk about Okay. Okay. Thank you I need, I 

[00:17:52] Martin: need the advice.

[00:17:55] Russell: but I think, on the basis of what we know now, there are things that we can do to mitigate some of those problems and we’re not.

 We talked about. Loss of vigilance, those microsleeps that , you can get when you’re chronically tired. And we talked about those junior doctors. And so, why aren’t we using devices which detect if the head is nodding, or the eyes, Uh, sort of, moving, or indeed if the car is moving laterally, and they will alert you fact that you’re falling asleep.

and of course, high end cars have got this. built in, but many instances, this easy technology is not being used. I was in Australia, last November, and I was chatting to the, mining industry there. And they now have introduced, eye tracking devices and, movement of vehicles to alert the driver that they’re falling asleep when they’re driving these thundering Great lorries. So that’s something which is easy. again, loss of vigilance in the workplace. We can increase the level of light, which increases the level of alertness. So that’s one thing we can do. And it doesn’t have to be the entire, room. It can be on the instrument panel or, or the area that you’re working.

We’ve talked about the poor physical and mental health. Well, why aren’t we introducing higher frequency health checks to catch these conditions like diabetes two or obesity or coronary heart disease before they become chronic conditions, you know, get the medications or the change in lifestyle in before this stuff becomes difficult and chronic.

One thing that I find extraordinary is that, we see higher rates of obesity, type 2 diabetes, metabolic abnormalities. What food do we make available in the night shift? It’s about as bad as it possibly could be. High fat, high sugar. Vending machines full of chocolate bars. and do you know, it’s interesting, I don’t know of any sector where we provide, uh, high protein, low sugar, low fat snacks that are easy to digest, that are nutritional and tasty. Now, the British food industry is one of the great success stories. Why we haven’t used that technology to develop something for night shift workers to reduce some of the risk factors of obesity and, type two diabetes, I’ve no idea.

It’s again, low hanging fruit. I think also education, the failure to be aware of the consequences of night shift work, not only to the individual, but also the people they share their lives with. So, for example, in some sectors, night shift workers have a divorce rate that is six times higher.

Then the same job during the day shift. People need to be aware that your partner hasn’t turned into a monster, but this is the consequences of somebody who’s driving their biology way outside of its normal physiological range. And I think we’ve got to make clear the abnormal behavior, to some extent, needs to be accommodated or at least appreciated.

So people aren’t, you know, thinking this person has just become a monster. I think also there’s a lot of anxiety about, screen use, computer use, and all the rest of it. And that’s also exaggerated. so, just one example. A study came out of the States a few years ago saying you shouldn’t look at a Kindle or an e book immediately before you go to sleep.

The study involved four hours of looking at a Kindle on its brightest light intensity on five consecutive nights. And at the end of that, it delayed sleep onset, and it was just statistically significant by And as one of my colleagues said when the data were presented, well, it may be statistically significant, but that’s biologically meaningless.

And furthermore, later studies show that if individuals got a reasonable amount of light during the day, about 500 lux, which is not that bright, then these small effects that were observed under dim light in the evening were completely abolished. So we’ve got to get to field studies. You know, before we start.

Making all these pronouncements, and, uh, suggested recommendations. We’ve got to get better data. The ability to cope with morning versus evening shifts. Now, there is a spectrum of chronotypes, morning types and evening types across the world. And you know, it’s not the complete answer, but it’s easy to chronotype somebody.

So if you’re a late type, then ideally you should be put on later shifts. and what you certainly don’t want is a late type. On a morning shift or a morning type on an evening shift, and that’s, accommodating an individual’s biology to the demands of work. The other thing that I think is important, and we don’t have the data for this, and this is where we need to do some studies, is that These pathologies, particularly the physiological problems, develop over time, so would it be smart to restrict night shift work to, let’s say, three or four years, then you’re off, some of the pathologies will wind back, because after all we have a wonderfully dynamic, flexible biology, and then you could go back on again.

so you’re not building up and up and up over 20 years. the problems that we see in long term Night Shift work. Now, as I said, we don’t have the studies, but that will be something that would be easy to do.

[00:23:05] Martin: I’ve got a hunch Russell, this issue of a chronotype I think is really interesting. I’ve got this hunch that if we were to sample any area of, defense. I think we’re going to find a lot of early chronotype, we’re going to find a lot of larks, and not many owls purely because basic training starts early.

JP and I, we’re going to go to a base in a couple of days. And we know what time is it four in the morning, we’re getting down there, Four o’clock kickoff. it’s crazy early. 

[00:23:33] Russell: So 

you’re driving on the 

[00:23:35] Martin: Yeah, luckily, it’s not far from my house. So yeah.

[00:23:39] Russell: our cognitive abilities at 4 o’clock in the morning are worse than if we consume sufficient alcohol to make us legally drunk. 

[00:23:47] Martin: Yeah, I’m more worried about that these recruits holding their rifles at four in the morning. That’s 

that’s what concerns 

[00:23:53] Russell: well, we should unpack, chronotype in a bit more detail. So there’s three important factors, one of which we have some control over. One is our genetics, where we have no control. So by the contribution to our genes, our parents are still telling us what time to get up and go to bed.

and so there’s a genetic component, and there’s some really exciting science. Subtle changes in some of those clock genes have been associated with morningness and eveningness. The second is age. So from the age of 10, there’s a biological tendency to want to go to bed later and later and later.

It peaks in women about 19 and a half, men about 21. Men tend to be later chronotypes than women. And then there’s a slow move to a more morning chronotype such that by the time you’re in your late fifties, early sixties, you’re getting up and going to bed at about the time you wake up. Got up and went to bed when you were 10, pre puberty, and that’s around about two hours earlier than when you were in your late teens, early twenties.

And that’s almost certainly due to the changing hormonal, levels associated with puberty. But the third thing is when you see light. Now this is really important because morning light advances the clock, makes you get up earlier and go to bed earlier, and dusk light delays the clock, makes you go to bed later, get up later.

And we did a study a few years ago, Kate Porchette, did this wonderful study looking at, uh, chronotypes in university students, and she showed that the later the chronotype, the less morning light they got, which would make them get up earlier, and the more evening light they got, which would push the clock to a later time.

So when we see light is important, and so in those, military recruits, They’re being forced to get out of bed first thing in the morning. They’re getting that morning light, which will indeed advance the clock. And so, the one thing that we can do about our chronotype is light exposure, and that’s what they’re doing, and that’s why they probably can cope to some extent with getting up early in morning.

[00:25:53] Martin: I think the people who are more extreme owls, just be selected out because they’ll struggle so much to perform cognitively early in the morning that they won’t They won’t make it through those crucible events. And so you just don’t find them 

later on in their careers. 

[00:26:08] Russell: Yeah. Well, it’s such an important point it sort of also, sort of spans into athletes. So if you think about swimmers, as I was, you used to have to get up really early in the morning to get in the pool for the training sessions. But the competitions were actually in the late afternoon, early evening.

and so in fact, that’s when, records are always broken in the late afternoon, early evening because our, core body temperature has increased, which means we’ve got greater muscle efficiency. So we’re actually selecting against the late types by these morning, sessions, who would do better in the late afternoon, early evening competitions.

And certainly, we lose a lot of athletes. Swimmers in particular because of those early morning training sessions.

[00:26:52] Martin: was never a swimmer. that wouldn’t have worked. I was never in the military either. I think that’s maybe one of the reasons I wouldn’t have done well in that environment, it’s too early in the morning for me for 

sure. Let’s talk about light. Now,

[00:27:03] Russell: Yeah,

[00:27:04] Martin: always thought of our eyes as the organ that we use to see things, you know, I know about rods, I know about cones, And it is only relatively recently when I started studying Oxford, coming to some of your lectures and understood a little bit more that there’s a whole lot more going on the eye around light. So can we talk about the eyes and light 

[00:27:24] Russell: yeah, 

[00:27:24] Martin: important.

[00:27:25] Russell: absolutely. And of course, this is, this is really the heart of what we’ve been doing for quite some time. and so really a long time ago in the late eighties, early nineties, I became fascinated about how in mammals, including us, we set the internal clock. There’s a master clock within the suprachiasmatic nuclei.

And it’s set by the light dark cycle. And everybody assumed, well, it’s the eye of course, because if you cover the eyes, or if you don’t have eyes, then you can’t set the clock, and so the clock will just drift through time. So it must be the visual system. I never said that. I was lucky enough to be taught as an undergraduate by, a chap called John Lithgow, who wrote this amazing book called The Ecology of Vision.

And basically in that book he was saying that, Photoreceptor systems are adapted to their particular task. Now, for vision, you have to grab light in a fraction of a second, forget you’ve seen it, and then move on. Otherwise, our world will be a constant smear of light dark exposure. But for the circadian system, it needs an overall impression of the amount of light at dawn and dusk over minutes and potentially hours.

And I couldn’t see how, an image grabbing system and a light detecting system for the clock could work. How could it be the same thing? So we started studying mice with hereditary retinal disorders, mice in which the rods and the cones had largely degenerated. They were visually blind. But we found that their ability to regulate their clock by light was unaffected.

It was such an unexpected observation. something else was in the eye. Now when we first proposed that there might be another receptor within the eye, I remember at a meeting. In the States, I sort of said, so our data are consistent with, there’s another light sensor within the eye.

And somebody, stood up. Looked at me and just said bullshit and walked out. and we had grants rejected. The argument was we’ve been studying the eye for 150 years. Are you seriously telling us, Foster, that there’s another receptor within the eye? and so anyway, we plotted on and what we ultimately did, because one of the criticisms was maybe there’s just a few rods and cones left. You haven’t completely eliminated these receptors and that’s all you need. So we then genetically engineered a mouse, no rods and no cones. And it was, as we had said, they were perfectly fine.

And then we showed that in humans and this led to the discovery that there’s a third receptor within the eye. which we’ve called the photosensitive retinal ganglion cells. Now the ganglion cells of the eye are those cells whose axons leave the eye and form the optic nerve and enter the brain.

And about one out of every hundred of those ganglion cells is directly light sensitive. Using a novel photopigment and novel light sensitive molecule. And these other receptors that are regulating the clock. Now, we thought that the visual cells, the rods and the cones and the PRGCs didn’t talk to each other.

Now we know that they do. And there is some influence by the rods and cones on the PRGCs. But the PRGCs are the only way in to the master clock. So it’s turning out to be absolutely fascinating. And what we’ve done most recently. is try and understand how those cells change the molecular clockwork.

And we’ve got a nice description of that in many areas. And so we’ve been able to develop drugs, which fool the clock. The master clock in the brain that it’s seen light. So those individuals with no eyes, for example, and we work very closely with Blind Veterans UK, extraordinary individuals, ferociously independent, and yet they say, I’m being constantly tricked by my body.

I want to get up and go to sleep at completely the wrong time. That’s because the clock is drifting through time. And so whilst they can cope with the visual blindness, the time blindness. It’s almost worse in some respects because it disconnects them from everybody else who they want to interact with.

we’ve now done, for one of our drugs, it’s gone through all the preclinical work, works spectacularly well in mice. We know it’s not causing any harm in with our in And now we want to go in and do the critical experiment show that we’ll shift the clock of a human.

And I have every confidence that it will. So my great hope is that I’ll finish my career by giving back a sense of time to the time blind. And it’s not just people. with no eyes. We talked about schizophrenia, those smashed rhythms. Maybe we could introduce these drugs to stabilize and then get a stable sleep wake cycle and then move onto a light dark cycle.

In neurodevelopmental conditions, in children, you get terrible disruption. In Alzheimer’s, dementia, the reason why Many individuals, are sent from the home environment into some form of, care home is because they’re wandering around in the middle of the night, terrifying and waking up everybody. So, you know, the ability to stabilize the clock using these new drugs could be monumentally exciting.

[00:32:43] Martin: That’s amazing to hear that research that you’re doing. I think it’s, it’s fascinating. It’s fascinated me for years. I always love listening to this stuff. It’s, uh, 

[00:32:51] Russell: You’re a convert. 

[00:32:53] Martin: uh, absolutely a hundred percent. Um, yeah, I’m a zealot for, for circadian neuroscience now. But, um, on that, there are well, let’s call them influencers.

I’m going to call them influencers. You get them on social media who talk a lot about early light exposure. And this movement about, getting out in the morning, getting a light exposure. Can you explain then why?

Why is it that we need light first thing in the morning? What’s that doing? And why? Why can’t you just get light midday? He’s just said the people who are potentially late are missing out on the early morning. So what’s the benefit?

[00:33:27] Russell: Well, that’s what’s so fascinating because the clock isn’t equally sensitive to light across the entire day. so we know that the clock is looking for light, as it were, at dusk and dawn. And when we were all agricultural workers, And of course, until recently, we all worked outside. we got dusk and dawn exposure, more or less, and certainly morning and late evening exposure.

And so our clock would stay aligned. Now, morning light advances the clock, dusk light delays the clock. And so we got this symmetrical light exposure, so we stayed on track. Our human body clock is slightly longer. than 24 hours. So what happens under constant conditions is that we would go to bed later and later and later and later each night.

We would drift. We’d show a daily delay in our circadian rhythms. So to be adjusted to the 24 hour day, we need a daily advance to compensate for that clock delay. Morning light. advances the clock. And that’s why morning light is so important, is that it compensates for that drifting delay, and it shoves the clock forward in time.

It advances the clock. So that’s why light in the morning is so critically important. And if you can’t get outside, then sit close to a window. The problem about being inside is that it’s incredibly dim. we live our lives in dim, dark caves. So average evening light conditions might be 90 lux, daytime conditions in an office, maybe 200, 300, maybe 400 lux, but it’s dim because shortly after dawn, Environmental light, even on a cloudy day, can be 50 to 100 times brighter in the morning than inside light.

And later, it’s even brighter than that. So the key thing is we need to get levels of light that we’d encounter outside, which is the thousands of lux. And that’s what’s been shown to be important for setting the clock in laboratory conditions. 30 minutes. of 10, 000 lux is incredibly effective at setting the clock.

Interestingly, those sorts of light box exposures have also been useful in depression. So for non seasonal depression, some wonderful experiments looked at a placebo, they looked at Prozac, and they looked at light, which as I say was 30 minutes of 10, 000 lux in the morning. And by, eight weeks, Prozac was statistically different from placebo, but by two weeks, Light was more effective than placebo.

And by eight weeks, it was hugely more significant than Prozac. So Light, whether it’s as a result of consolidating the sleep wake cycle, or whether it’s having another function, and we know that those PRGCs are plugged into a whole range of other structures within the brain. Some which are associated with mood.

So it may well be that these PRGCs are regulating not just the clock, but also our alertness and our emotions as well.

[00:36:51] Martin: Get out in the early hours. That’s what we need to be doing.

[00:36:54] Russell: Yeah, I think that’s right. and it’s anecdotally, there’s some studies which have suggested that those people who own dogs, tend to have a better mood. And that’s always associated, well, it’s a companion animal. I think it’s because you have to get up in the morning, take the dogs out to empty them.

and that’s when you’re getting your morning photon shower. and it’s, it’s helping consolidate the circadian and sleep

wake timing systems. 

[00:37:17] Martin: I definitely endorse that we may hear my dog barking she might be agreeing with that as well

[00:37:21] JP: Russell, within the Armed Forces Emergency Services and First Responder communities, there’s a concept sort of been developing since around 2006, known as human performance optimization, and HPO is essentially the use of science and technology to enhance individual performance capabilities up to the limit of one’s biological potential.

Now, quite often, HPO is explained utilizing the biopsychosocial model, so you talk about the physical, the psychological, and the social component. But our degree, argue that that’s oversimplification, and that HPO should be viewed through key domains, mainly physiological readiness, psychological resilience, human cognitive capabilities, and nutrition, and sleep.

And what’s really fascinating is obviously there’s this acceptance that sleep is important, But a lot of times within the HPO literature, people only refer to the education around SWEEP and there’s very little, information that sort of relies through us to enhance. sleep, given the contextual requirements of these population groups?

So it’s going to be quite a broad question, but given the task demands of these sort of organizations and the reality of their operational context, what sort of advice would you give to them in terms of enhancing their quality and quantity of sleep?

[00:38:32] Russell: okay, well, of course, sleep is the best and safest cognitive enhancer known to humankind. so there’s no question we have to get sleep. to be fully functional humans. how to get it? Well, it’s complicated, particularly if you’re a shift worker. So we’ve talked about ways of mitigating the problems of sleep.

other strategies. So, we’ve talked about, if you can, getting that morning light to stabilize the sleep wake cycle. But many people find it difficult to get to sleep. They’re wired. And so many people don’t have a sleep problem. They have an anxiety or a stress issue. And so finding ways to calm down, to relax at the end of the day before sleep, or at any stage when you’re trying to sleep is critically important.

and so I think relaxation techniques, I was extremely rude about mindfulness. When it first emerged, had it in the same box as crystal waving. and I abjectly apologize for my, dismissal because now the data are there, for some people, mindfulness can be a great way of relaxing and, aiding sleep.

so I think that that’s something, absolutely critical, that we need to take on board. when you’re trying to sleep, relax. We’ve talked about light, but let’s just emphasize that, that, increased light will increase levels of alertness and delay sleep onset. So try and minimize light exposure.

And again, with all the devices, it’s not so much the light from because it’s really low. It’s the energizing effect of looking at emails, doing social media. and so try and be controlled. and leave your smartphones and all the rest of it outside of the sleeping space. it’s important not to use alcohol to sedate yourself or indeed things like antihistamines.

There’s antihistamines you can buy over the counter which pass the blood brain barrier. Phenegan, for example. when I first heard about Phenegan, I thought, well, I better give it a go. you know, I’m talking about these things. Let’s see. So I took a tablet on a Friday evening. Wipe me out.

Unbelievable that such powerful sedatives are available, over the counter. Please don’t take them, because takes ages to recover from some of drugs. also try and make sure that the sleeping space isn’t too warm. Part of sleep initiation, going to sleep, is a drop in core body temperature.

actually if you block that. you can make it more difficult to get to sleep. So, obviously don’t keep the bedroom too warm. So we’re talking about 17, certainly no higher than 18 for, people in their 20s. young to mid years, 70 year olds might need it a bit warmer.

There’s a study suggesting a bit warm is good. But another technique that people use is to have not a hot, but a warm bath or shower. Cause what that does is vasodilate or dilate the blood vessels of the skin, which means that blood is shunted from the periphery to the core where it can then give off, obviously keep it dark.

Clock watching is a really big problem. So, many people have an illuminated dial of their clock. a digital clock of some sort. And you will invariably wake up at some point. You’ll look at the clock and think, Oh, God. Bloody hell, I’ve got to get up in an hour and a half, and then they sort of, abandon sleep and then start doing emails or drinking coffee.

So my advice is it matters when the alarm goes off, not how long it goes off. we know that a nap can be extremely useful, a 20 minute nap can be useful during the day at improving sleep. Cognitive performance, and we can maybe unpack naps a bit more. So, even if it is 20 minutes before the alarm goes off, it’s still worth having that, sleep.

so that’s important. don’t. pay too much attention to sleep apps. They are really misleading. It’s important to appreciate that none of the sleep federations endorse any of currently available apps. And none of them are FDA approved. it’s okay to tell you roughly when you went to sleep, if you woke up in the night and when you finally woke up.

But if they start saying, Oh, you had a good night’s sleep or lots of slow wave sleep or lots of REM sleep, that’s really misleading and it can get people incredibly anxious. Don’t take them seriously. Keep a routine if you can. it’s very difficult of course for night shift workers and the military. noise, big issue, earplugs might be important. and if you’re sharing a room with somebody else who’s snoring, that can be a real problem. if you’re in a relationship, it’s easy.

you just keep a routine. jab them in the ribs. No, I’m joking. you find an alternative sleeping space and actually it works brilliantly. You both get a good night’s sleep. and you just need to make sure that they don’t have obstructive sleep apnea or something like that. But, if earplugs don’t work, it is a real problem.

and also if you wake up, don’t get anxious about it. You’ve got to stay calm and invariably, if you are tired, you will get back to sleep. As I say, one of the great problems is that people wake up and think, Oh my God, I’ve only got an hour and a half before I have to get up. and then they get stressed and they don’t fall back to sleep.

You can leave the bed or the sleeping space. listen to some relaxing music, maybe a few pages of Jane Austen or whatever the military might like to read, as long as it’s not too exciting, and that will then help you get back to sleep.

[00:43:48] Martin: I’m gonna keep my eye out for jane austen now wherever i’m whenever i’m on a on a base I’ll know they’ve listened to this podcast if I see it around

[00:43:56] Russell: It’s interesting. did a public talk and I said, you know, you have a few pages of Jane Austen, and somebody came up to me afterwards and said very seriously, Does it have to be Jane Austen? I said, No, no, it can be anything that sort of relaxes you. I wake up and I listen to Radio 4 Extra. Other people use, um, Melvin Bragg in our time. 

[00:44:15] JP: that works for 

[00:44:16] Russell: is that what 

you do, JP? Yeah, 

it’s interesting. It’s a great program, but boy, in the middle of the night, it can help me get back to

[00:44:21] JP: It’s good, it’s good for calming me down, actually. I do do it on occasion, on the BBC Sounds app, It starts off and I sort of engage in the topic, and then the next morning I’ve 

missed half of it and I have to pick it up again, but.

[00:44:31] Russell: Yeah. Well, that’s the thing. you can always catch it up later. You can always then learn about, Chinese porcelain of the Ming Dynasty, um, at some later point.

[00:44:39] Martin: Before, before we come back to NAPS, because I do want to talk about NAPS, I’d like your opinion. Now, in the US Marines, they used to say they owned the night. there’s areas of defence, which exclusively did night ops. So I’m wondering, We are a diurnal species, right? We, we’ve evolved with that, solar pattern. as you’ve said, we’re more alert when the sun is up. some animals are the opposite. They’re nocturnal. Can humans become nocturnal? in high stress environments, like the military where you’re doing night operations or it’s some kind of.

night workers who have to be alert overnight. Is it physiologically possible to make them nocturnal?

[00:45:18] Russell: yes and no. If we look at standard night shift work, 97 percent of night shift workers do not adapt to the demands of working at night. and that’s because they’re under dim light in the work workplace, and then brighter light on the journey home. And therefore they’re getting morning light exposure.

The clock always defers to the brighter light environment as daytime. And so. You don’t shift there are examples where you can shift. In the North Sea, the oil rig workers, and this is pioneering work by Josephine Arendt, and she showed that they do adapt to the demands of working at night on the rig.

That’s because they’re exposed to huge great arc lights, but during the day, they’re sleeping in metal beds. windowless boxes. And so they’re not getting that daytime exposure. So they will then lock on to the brighter light at night and the clock will think it’s daytime. So they will shift. And of course, if we cross multiple time zones, we do shift to the new time zone.

Some studies from, from Harvard showed that if you, increase the amount of light during the workplace, um, to several thousand lux, and then hide people from daylight, then those nightshift workers adapted to the nightshift. So, owning the night would mean that you would have to, get light during the night, and no light during the day, and the clock will adapt.

so, I don’t know how they do it, but that may be the means whereby they own the night. But, I should say. One of the problems about a tired brain is that it doesn’t know how tired it is. And healthy young males can squirt out stress hormones to override the clock. they can’t possibly expect that.

Peak performance. But because you are cognitively impaired, you can fool yourself that you’re okay. And that’s the great risk. so know, some studies done on taxi drivers night shift taxi drivers and said, you know, how’d you cope? They said, oh, it’s no problem. I’m, I’m fine. You take ’em into the lab and you look at their reaction times and cognitive abilities, they’re blasted away.

so the tired brain can be delusional about its abilities.

[00:47:37] Martin: I know I’ve got a device. I got a little gadget. I bought it the other week. You may have seen them. It’s these glasses that have on the insides. I first saw them at Oxford. There’s various brands of them, but they shine a green light into your eyes And I was showing them to friend of mine had a military career.

And he said, it looks like, You like wearing night vision goggles because were known as the men with green eyes. Do you think that green light exposure from a night vision goggle is that sufficiently strong enough or the right wavelength to potentially affect the master clock do you think?

[00:48:09] Russell: you raise an important point about spectral sensitivity or, color. Now those photosensitive retinal ganglion cells, we showed that they are maximally sensitive in the blue part of the spectrum. and the lambda max is 480 nanometers. and what that looks like is the blue of a very blue sky.

and so that’s where these receptors peak, but they have a bell shaped response. So it’s not as though they won’t be activated by shorter wavelength, sort of violet light, for example, or longer wavelength orange or yellow light. it’s just that it will take more. red light or orange light to activate them to the same level as 480 blue light.

The point I’m trying to make is that if the light is bright enough, it really doesn’t matter what the wavelength is. So bright white light is fine. And there’s a whole market that’s opened up on producing blue enriched devices to shift the clock. Actually, it’s unnecessary. if it’s bright enough, it doesn’t have to be blue.

but it depends on how you’re using these, goggles. They can be used to increase alertness at almost any time. but, can they be used to shift the clock? Well, if you’re living under very dim light conditions, if you’re on the Antarctic stations, for example, you could wear them when it should be morning, and you could put them on and that would give you your photon shower to set the clock.

and it’s interesting that, The Greenpeace base, didn’t have any form of light exposure, and these people waking up and going to sleep all over the place, whereas the military bases were using some controlled light exposure, and they were much more, stable in terms of the sleep wake cycles.

So, yes, I think they do have a role, I’m not aware of any really good studies which have shown the effectiveness. So you’ll find a lot of this sort of stuff. So people Say, ah, well these new receptors, they need a lot of light, blue light, we’ll build a device that optimizes activation of those receptors, but then they never really test their effectiveness.

And we are in a slightly difficult position at the moment, whereby recommendations are coming out about the intensity, the wavelength of light that will shift the clock or stabilize the clock in the sleep wake cycle. But it’s really. complicated because one’s age will influence our sensitivity to the clock.

one’s light history, how much light exposure you’ve had outside. So we’re not really in a good position to provide really good guidelines in my view at the moment. And in fact, guidelines can be misleading. there’s some stuff that’s come out suggesting that, you shouldn’t see more than 40 lux two hours before you go to bed.

Well, that’s based upon lab studies and I don’t, think that’s at all relevant. And if you’re elderly, then the danger of falling under dim light conditions I think is much greater and actually you can get an effect with 40 lux, but it has to be after an exposure of dim Seven, eight hours.

And it’s mainly on young people, and young people tend to have more sensitive clocks. So, you know, it’s messy at the moment.

There’s huge misinformation out there. I mean, one of the things that you see all the time is that melatonin is a sleep hormone. If you get light in the evening, it suppresses melatonin and you can’t get to sleep. No. Melatonin is a very mild modulator of sleep. It is most emphatically not a sleep hormone.

so, you know, for example, the study that showed the greatest efficacy of melatonin, which is something like, I can’t remember the dosing, but let’s say three milligrams, before bedtime, reduce the time it took you to get to sleep by about 20 minutes.

Now that’s significant, but that was the best study that’s ever been undertaken. Many experiments showed that it had no effect at all. There seems to be lots of individual, again, individual variation to responses to melatonin. it’s a great placebo. and many people swear by it, but actually the overwhelming amount of scientific data suggests that it’s a mild modulator of sleep at

best. 

[00:52:07] Martin: I was amazed traveling to the United States seeing gummies, melatonin chocolate, melatonin beers. They seem to put it 

[00:52:16] Russell: Yeah, well. 

[00:52:17] JP: It’s

[00:52:18] Russell: and it’s really interesting because I was interviewed just recently by a journalist who’s doing an article on this spate of instances of kids, eating melatonin filled gummies thinking that they’re normal gummies and should we worry about that? My view was probably not because it will have a mild effect.

It’s not as though, you know, they’re taking aspirin or something really potentially dangerous in large quantities. so my feeling was that it’s something that we shouldn’t get too worried about. Although, think it’s a bit irresponsible for parents to leave anything like that within the reach of children.

I think the emphasis should be on parents keeping any medication, even if it’s pretty harmless, out of the way children. 

[00:52:58] JP: I was chatting to a professor, Natalie Patton, she’s over in Belgium, a couple of weeks ago and we were talking about a book called Blitzed and it’s a fascinating book because it’s about the use of amphetamines within the Third Reich and we were talking about this point where they were taking his Pruvitin they used to call Panzer Schokolade basically they had this amphetamine waste chocolate and the author makes this brilliant a hypothesis that one of the reasons why Blitzkrieg was so successful was that the, Wehrmacht and the, the armoured element of the Wehrmacht were essentially high.

and they were able to maintain a very very high up tempo which kept the allies on the back foot however there was a price to be paid and that price was paid funny enough just as they hit Dunkirk and it wasn’t necessarily a strategic decision to stop them it was a case they just couldn’t go anymore because they’d been operating at such a high tempo for almost a week but it was driven by the fact that they were taking amphetamines to offset the sweep it was just fascinating

[00:53:57] Russell: That’s so

[00:53:57] Martin: A derivative of crystal meth, I believe it was. It’s 

[00:54:01] JP: yeah, 

[00:54:01] Martin: recommended. 

[00:54:02] Russell: I was told, you guys probably know better than I did that during the first Gulf War, amphetamines were used by pilots, and, also ground crew to again, stay awake during the,

operations. The problem was that, after coming down from amphetamine use, they became, um, Kind of trigger happy and there was a lot of friendly fire instances.

I think a bunch of Canadian troops were shot up by American troops because of coming down from amphetamines. So, yeah, they can have major disadvantages, but I’m fascinated about that, Dunkirk, issue. 

[00:54:38] JP: I think the Americans, they still issue them, they call them stop or go tablets, so the go tablets are the amphetamines and the stop tablets some sort of sweeping pill, but I think the decision to use them is based on operational circumstance at that time, so if it’s going to be a high up tempo, it’s deemed a reasonable risk for it to be issued.

[00:54:54] Russell: there’s another drug that has been developed, called ProVigil. 

And it was developed for narcolepsy, which is this condition where you uncontrollably sleep. And, it was used by French troops, I believe, during the first Gulf War. And then it’s been used, by other, soldiers later on. When you look at its ability to stay awake, it’s probably not much better than caffeine.

but of course you don’t have the, coming down off of, caffeine and provigil that you do from amphetamine 

[00:55:23] Martin: Yeah, I think it’s a good point to just recognize that we’re not medical doctors and we don’t advise anyone to use these, uh, drugs. But let’s talk about naps because did mention naps earlier. And this is a fatigue countermeasure. It’s a performance enhancing strategy, potentially, you can get a similar effect in terms of alertness.

So can you us a little bit more naps and why they’re 

potentially useful? 

[00:55:47] Russell: Yeah. Most of the research that I’m aware of has not been done in the military or in night shift workers. It’s been, you know, if you take a nap during the middle of the day, what’s the impact? And essentially, A nap no longer than 20 minutes, is considered to be useful because it will improve the quality of your cognitive performance during the second half of the day.

longer than 20 minutes you can fall into deeper sleep and recovery from that deeper sleep can be counterproductive. So you can have that sleep inertia, you can feel groggy. So, occasional nap. It’s fine. and certainly within the context of the military or indeed night shift work, it’s probably a good idea.

In fact, some of the recommendations, are that you should have a nap immediately before you go on to the night shift, because that’ll push back the need for sleep, which means you can stay vigilant during the day. So that’s one of the techniques that night shift workers use. The problem about napping is that it can get out of control.

And the best example of that is in teenagers. they are biologically programmed to go to sleep later. That’s enhanced by social media. So night time sleep for many adolescents is quite short. Often five hours, for example. And the recommended window is something in the region of nine hours.

for optimum daily performance. Varies a lot between individuals. So they struggle through the school day. They can’t make full use of their cognitive performance. they can’t make use of their full, cognitive abilities. So, not making a full opportunity of their educational exposure.

And then they’ll go home and then they’ll have not a nap but a one or two hour sleep. That pushes back the need for sleep that night, making it more difficult to get to sleep. And so you can fall into a trap of shorter night time sleep and longer day time sleeps. that you want to avoid because, you know, you’re basically impaired for two thirds of the day, in fact.

but the occasional nap is fine and it’s probably very useful under some circumstances for night shift workers and the military. 

[00:57:54] Martin: think that the term the power nap, that’s a, a label that gets thrown around that it originated in NASA. I think it was 

[00:58:00] Russell: Yeah. 

[00:58:00] Martin: series of research done 

[00:58:02] Russell: there is a trend though of having inappropriately called polyphasic sleep, which is confusing because there’s biologically polyphasic sleep, which is when you wake up and go back to sleep several times in the night. And this is where people actively, um, Use an alarm clock to get, let’s say, two hours of sleep at night, and then they’ll have, a couple of 30 minutes or one hour sleeps during the day.

So their total sleep is not more than four hours, two hours at night, and then a couple of sleeps during the day. And this has become really popular for, the business sector, and some other areas. And the data there is quite clear. This is not a good idea. And you should not, impose that sort of polyphasic sleep pattern upon your biology.

[00:58:46] Martin: helped people. adopt that polyphasic pattern because they’re doing, for example, single handed rowing across the Atlantic. And they’ve had to do that for safety reasons. They’ve had to adopt that polyphasic pattern. And while it is possible, possible. I’m sure anyone who’s listened to that have tried it will tell you that you don’t feel great. Over 3540 days of rowing across the Atlantic or however long it takes. These people, are in a bad state by the end of it. And part of that is 

due to that polyphasic sleep pattern, I’m sure of it.

[00:59:16] Russell: Yeah. And you can make some really stupid decisions actually, it’s a very good point. If things are stable and calm, then you can get by on relatively little sleep because, you’re just basically on, automatic mode. But if you’re challenged in any way, as you might be if you’re driving, or if you’re rowing the Atlantic that’s when you are particularly vulnerable, because the brain is not in its best shape to try and make sensible decisions about how to get you out of that mess.

[00:59:44] Martin: Can we talk about food very quickly? briefly mentioned it and I remember a television advert a number of years ago fast food company who advertised that they were supporting our frontline workers, our blue light services, because they were staying open 24 hours.

So any of these, night workers could go and enjoy their fast food at any time at night. And I remember thinking, if they really want to help these people, the best thing they can do is close. So you don’t give them the option. So what what are the risks? They’re all joking aside around me eating my deliveries at 11.

know, never, never past 

6pm, honestly. 

[01:00:18] Russell: you’ve admitted that in 

public, Yeah, What’s the potential dangers of eating late at night 

Yeah. before I answer that question, Martin, I think you’ve raised a good point is that just because we can run society on a 24, seven basis, do we always need to? And I think we do need to weigh up the costs and benefits of that. just cause we can, should we? and so I think, the fact that our supermarkets can be open, 24 hours, um, Is that really essential in view of what it might be doing to the people running those, shops?

Anyway, that’s, I think a matter for discussion. so food intake. Our metabolism is very tightly regulated by our circadian system. And this is illustrated beautifully by, if you give the same food three times a day, or if you infuse a constant flow of glucose into somebody. Then that food is metabolized and taken out of circulation.

The glucose is cleared from the circulation faster in the morning lunchtime compared to the evening. And in fact, if you eat at the end of the day, you’re not going to be mobile, so you’re not going to be burning those calories off. If they’re hanging around, they’ll be consolidated to stored calories in the liver or in fat.

So it’s wise not to calorie load towards the end of the day. And it’s worth bearing in mind that because of, uh, Modern society, our eating habits have changed profoundly. In the 11th century, all the way through to the Tudor period, the main meal of the day was, breakfast. lunchtime was very important, and very light snacks towards the end of the day.

so, you know, we’ve shifted our eating habits, largely because so many people have to commute to work, they don’t have time for breakfast, they rush off driving or on the train, They have a light lunch at their desk because they’re pressurized. And then finally get home and you put the, sugar, rich, wonderful thing into the microwave and ping.

And so your calorie loading at the end of the day. And this is really not a good idea. increased risk of metabolic syndrome, type two diabetes and obesity. So an interesting study from the University of Chicago looked at healthy young males.

One group given four hours of sleep per night, only allowed four hours, the other up to ten if they wanted it. and, what happened after several days of this is that the hunger hormone went up hugely The satiation hormone went down and carbohydrate consumption, particularly for sugars, went up by something like 35 to 40 percent.

So one of the problems that night shift workers face is that they are hungry and they’re hungry for carbohydrates and sugars. and of course then they’d be eating those sugars, at the worst time of day. So there’s a double whammy that night shift workers face. they’re active at night when their body doesn’t want to see high levels of calories and their hunger system is turned on because they’re tired.

[01:03:24] Martin: See. You mentioned the circadian rhythm is about getting the right biological materials in the right place in the right volume, intensity, does that come into play then during the night? I’m thinking insulin release. I’m thinking, the enzymes, the digestive enzymes, they’re just not, they’re not 

there, right? 

[01:03:39] Russell: absolutely. So it’s really fascinating if you think about it. metabolism is in essentially two states. So during the day we’re taking in calories and we’re burning those calories up for energy. We use them as, as we get them, largely speaking. If we have excess, then we deposit them. But at night, of course, we’re asleep.

And so to live, to survive, we’re mobilizing stored calories. And so The recommendation is, that if you want to exercise to lose weight, then about of exercise before breakfast, While your body is still in the sleep state of mobilizing stored calories is actually rather helpful. The trouble is first thing in the morning your core body temperature hasn’t risen, your metabolic rate is rising but it hasn’t reached peak.

That can occur late in the afternoon and early evening and so you can exercise with greater vigor and longer later in the day. And so, you can burn more calories that you’ve taken in during the day by exercise later in the day. So the strategy, optimum strategy that seems to be going around at the moment is a short bout of exercise before breakfast, followed by a longer bout of exercise when you can exercise for longer with greater vigor later in the day when core body temperature has risen and metabolic rate is

peaked. 

[01:04:59] Martin: I’m interested, it’s almost like we’ve got these two fields of chrono S and C developing. JP, that could be 

[01:05:05] Russell: Oh, yes.

[01:05:06] Martin: you. 

[01:05:07] JP: ties in quite well, because you’ve got this concept known as concurrent training, where you combine strength and endurance training. they’re quite divergent modes of training, and they can elicit what’s called an interference effect. An interference effect occurs on the development of rate of force development, or maximal strength, but it doesn’t seem to occur in regards to the endurance attributes.

And what’s interesting is when you look at some of the molecular signalling hypotheses behind this is that when we conduct endurance exercise, it activates the AMPK pathway, which has a half life of around six to seven hours. However, when you conduct strength training, it activates the mTOR pathway, mammalian target of rapamycin pathway, and that has a half life of 15 hours.

So if you think about that then, it’s like, well, endurance training in the morning, manage acute fatigue, allow that half life to dissipate, six to eight hours, then wait afternoon when you’re at that optimal, condition, conduct your strength training, and then you can utilize and maximize the activation of the mTOR pathway overnight.

So it’s sort of, you can see that alignment actually works really well.

[01:06:10] Russell: fits 

nicely. 

[01:06:11] JP: So people have been doing strength training first thing in the morning, might want to just change that. Maybe do a bit of endurance training, strength training in the afternoon and

go.

[01:06:17] Russell: Well, absolutely. I mean, they’ll, be able to perform, with greater endurance and, and greater power later in the day. that’s clear. In fact, it’s quite interesting, you know, they’ve looked at, time of day and, breaking records. And many sports records are broken in the late afternoon, early evening.

[01:06:32] Martin: That’s when the TVs are on there. that’s for TV audience.

[01:06:36] Russell: yeah, well, that’s interesting, too. But that’s actually when biologically you’re going to be able to break those

[01:06:41] JP: But you can see the synergy. The synergy between obviously neuroscience, sleep, physiology, the training prescription, it all comes together.

[01:06:49] Russell: Yep, absolutely.

[01:06:51] Martin: teams. That’s the way that’s the way forward. Absolutely. now Russell, I’m acutely aware you’re a very busy man and we’ve had you on for a long time.

So just wrap up, what we like to do is just to offer over to you to give us the final words to reiterate something that’s particularly important. Maybe mention something that you want to talk about, haven’t talked about yet.

So to finish the episode over to you, how would you like to close?

[01:07:15] Russell: think it’s so important to appreciate that, sleep is our, the best cognitive enhancer we’ve got. And we should no longer think of sleep as an indulgence or a luxury. And appreciate that sleep essentially defines our ability to function during the waking day. we’ve moved from sort of the 80s where sleep was regarded as sort of an indulgence and, people would come in and say, Oh, I’ve done another all nighter.

Oh, fantastic. Well done. To now the situation where we realize that you don’t want sleepy people around. They’re going to be overly impulsive. They’re going to make poor decisions. They’re not going to be able to think creatively or communicate. And so we’ve, got to embrace sleep. I think so. Many people think of sleep as this sort of enemy that we have to sort of grapple and bludgeon into submission.

Whereas, in fact, we should think of them as a, lovely friend that we want to cuddle up to and embrace. So, perhaps I finish on that rather, 

squishy note. 

[01:08:14] Martin: Thank you very much. I will. give a shout out to your book because the lifetime your book is one of my favorites on the topic of sleep. so I highly, highly recommend that. And I will put it in the show notes. But if anyone does want to learn about what you’re doing or make contact to understand research, what’s the best way of people following you and seeing what you’re up to?

[01:08:37] Russell: Yeah, I mean, I think look for the Sleep and Circadian Neuroscience, SCNI Institute, on the University of Oxford. I mean, I’m privileged to work with a whole host of different sorts of experts and research teams.

So it’s a really vibrant environment here in Oxford. And so if you’re interested in Sleep, Circadian Rhythms, check it out. Do take the time to

look 

us up. 

[01:08:57] Martin: Thank you very much for your time Russell. That has been a fantastic episode. 

[01:09:01] JP: Yeah, absolutely brilliant. Thank you.

[01:09:03] OUTRO: Thank you for joining us on the Optimizing Human Performance podcast, a Wavel Room production. If you’re enjoying this content, don’t forget to like and subscribe so that we can keep improving. And remember to visit wavelroom. com to find their latest articles, podcasts, and newsletters. If you know someone who could benefit from our discussions, please refer them to our show.

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