The science of sleep with Professor Russel Foster …Brave New World podcast

The pair discuss everything from sleep hygiene, our circadian rhythm and body clocks, the impact of technology before bed and whether it actually affects us, the myths, and even some tips to improve longevity. This episode also includes excerpts from Eight Sleep founder Matteo Franceschetti, the pop star Rita Ora, and the author and actress Davinia Taylor.

Topics discussed in this episode:

Get in touch with us at podcasts@standard.co.uk.

Welcome back to Brave New World, The Evening Standard’s podcast on all things science, medicine, and the future of humanity.

I’m your host, Evgeny Lebedev.

And in this series, we’ll be taking a look at the latest developments in neuroscience, longevity, sleep, and much more.

Join me as I engage in thought-provoking conversations with some of the brightest minds of our time.

The press is awash with news and stories about sleep, with more and more people excited about the latest research and technology in the field.

A field that is being revolutionized before our eyes, with wearables, smart mattresses, and new information about the right diet, the right routine, in short, the right step to take to optimize your sleep, which in turn optimizes our life.

In this episode, I speak to experts and to executives in the sleep fitness space to try and establish the guidelines for a perfect sleep.

Now I am joined by Russel Foster, who is a professor of circadian neuroscience at Oxford University and one of the world’s experts on sleep.

Russel, welcome to Brave New World.

We’re here to talk about sleep.

So, sleep is something that’s fascinated us throughout centuries.

There have been multiple paintings, artworks, works of literature, Shakespeare, Goya, Blake.

Why do you think sleep has been so fascinating to us?

Well, first of all, we’re really delighted to join you.

And of course, if we ignore sleep, we ignore 30% of our existence.

And I think the pre-industrial era, you mentioned Shakespeare, for example, there was an intuitive appreciation of why sleep is important.

If you think about some of the quotes of Shakespeare, the honey heavy dew of slumber, sleep, sleep, nature’s softness, how have I forsaken thee?

We embraced it and I think we recognized why it was so important.

And so I think historically we’ve been very good about sleep.

But with the modern era and the sort of headlong rush into modernity, we’ve tended to think of sleep as an indulgence or an extravagance, almost like an illness that needs a cure.

And so, we’ve forgotten the immense value of sleep.

The quality of our sleep defines the quality of our daytime consciousness.

And thankfully, I think we’re beginning to take back some control about sleep.

Yeah, it’s interesting you say that in our culture, because I don’t know if it’s still the case, but it used to be until recently, that people were very proud of how little they slept.

I think it was Margaret Thatcher who prided herself on sleeping three, four hours a night.

No, I think it’s very interesting.

And the culture of the 80s is probably where it got to its worst point.

I remember people coming in and saying, “ah, I did another all nighter”.

And they were given a slap on the back and thought, “well done”.

And actually, these are the last sorts of people that you want as colleagues.

They can’t think straight.

They can’t make sensible decisions.

They can’t evaluate information.

They fail to pick up the social signals from their colleagues, friends and family.

They don’t have a sense of humour and they have greater levels of impulsivity.

This is not what you want in somebody that you’re working with.

And of course, particularly in our politicians.

And I did speak to one of Margaret Thatcher’s aides several years ago and they said, “yeah, absolutely”.

You know, red boxes used to be delivered late at night and they would be done by morning.

And of course, Lady Thatcher, you know, died of dementia, with dementia.

And now we’re understanding what those links are, which is very interesting.

Yeah, it’s been correlated that there’s poor sleep in the middle years as it correlated with high rates of dementia in later years.

And now we’ve got some understanding of the mechanisms.

So, for example, during sleep, this misfolded protein, beta amyloid is cleared and got rid of from the brain.

But if you don’t sleep, that clearance of beta amyloid, which of course is associated with high levels of dementia and Alzheimer’s, is not cleared.

Even one night of no sleep, you can detect slightly higher levels of beta amyloid within the brain.

It’s not just hand waving.

We’ve got a mechanism which explains why dementia is going to be more common in individuals with poor sleep.

Now, I wouldn’t say if you don’t sleep, you’re going to get dementia.

>But what it suggests very strongly is that if you’re vulnerable to those pathways that cause dementia, this is a significant risk factor.

Correct me if I’m wrong, but we’ll come to this anyway, but this happens during deep sleep.

It seems to be a phenomenon of deep sleep, yes.

But of course, the different stages of sleep, precisely what they’re doing is still hotly debated.

So deep sleep, memory consolidation, and the processing of information.

Whereas in REM sleep, that’s been associated with the processing of emotional responses and things like that.

And of course, it’s during REM sleep, we have our most vivid and complicated dreams.

So, dreams is the other thing I wanted to touch on.

And in the opening question is the, you talked about the pleasurable side of sleep, but there is the dark side of sleep or dreams in some cases, as you think about the Goya pictures of the sleep of reason awakens monsters or the idea of Freud saying that the subconscious comes up through dreams.

What is the dark side of sleep?

And our dream is very important.

Well, I wouldn’t say there was a dark side.

I mean, many of us, and I just had a rather anxious period.

So, I’ve had my anxiety dream, which is bizarre because it’s essentially protecting the children from a saltwater crocodile that has entered the hall.

I mean, you know, crazy stuff, but I get it when anxious.

And is there something that recurs for you?

You know, during periods of anxiety, so it was a pretty anxious time.

But actually you can take solace because during REM sleep and these very vivid dreams, it’s the brain trying to make sense of a complicated emotional world.

So, it’s actually your brain working with you to try and deal with the anxiety and stress.

Very interestingly, if we think about the types of dreams that New Yorkers had after the Twin Towers were destroyed by terrorist action, it wasn’t images of planes crashing into buildings.

It was being overwhelmed by a tsunami or being mugged.

These were classic sort of anxiety dreams.

And so, you know, when people talk about these sorts of things, I say, don’t get worried about it.

This is something that is fine.

You’re dealing with your anxiety.

Now, I think we need to make a distinction, though, between an anxiety dream with post-traumatic stress.

And that’s different, which is, again, a recapitulation of the images that you’ve experienced.

And that is something different.

And if it’s something that doesn’t go away, one might need to get some help to deal with.

I mean, a classic of soldiers, for example, and appalling post-traumatic stress as a result of sort of war zone and combat.

What’s really interesting is that we have some data which suggests that if you sleep-deprive people after a traumatic experience, you can reduce what’s called the intrusional memories, the flashbacks.

Now, current practice is to do the opposite, which is to encourage people to sleep after a traumatic experience.

But of course, not sleeping fits in with what we know about memory consolidation.

Memory consolidation can, to a large extent, occur whilst we sleep.

So, sleep-depriving somebody after a traumatic event might be protective.

And it’s quite interesting if you think of the old historical practices.

You know, what did soldiers do after battle?

Well, they got drunk and they stayed up all night carousing.

Alcohol will impede memory formation as will staying up all night.

And so, maybe these were almost unwitting protective mechanisms to reduce the chance of these horrific recalls during post-traumatic stress.

And so, what is the body clock?

What is circadian rhythm?

Well, if we step back, we think about our biology.

What our biology needs is to do the right stuff at the right time.

We need the right materials at the right concentration, delivered to the right tissues and organs at the right time of day.

And it’s the circadian system that gives this structure in both time and space.

Well, we live on a planet that revolves once every 24 hours.

And the worlds of darkness and light are fundamentally different.

And we, and essentially all life on Earth, has evolved a biological response to adapt to those different states.

So, in humans, of course, the daytime state is a state of consciousness and activity, whereas the nighttime state is a period of sleep and a whole bunch of associated biology.

And what the circadian system can do is anticipate these predictable 24-hour changes, fine-tune our biology to these varied demands.

So, for example, in anticipation of waking up in the morning, blood glucose rises, core body temperature rises, so that as soon as morning comes and we wake up, we’re ready to act optimally in that new world.

If we simply waited to change our biology with morning light, we’d wait two to three hours of adaptation, whilst we, you know, geared up our biology to the demands of activity.

It’s an illustration of essentially the predictive power of an internal clock.

But I think you can think of it as this time stamp, this sort of to everything that’s important about our biology.

So how is that predetermined?

And can we change it in any way?

I mean, one of the, I think, great success stories in neuroscience over the past 20, 30 years has been understanding how circadian rhythms are generated.

And in fact, the Nobel Prize was given to three friends in 2017, who discovered how the clock ticks, not in humans, but in fruit flies.

As it turned out, the fundamental mechanisms in a fly are common to all animal life, which is extraordinary.

And so, what we’ve got is a bunch of genes, which are then turned on.

They produce a bunch of proteins.

Those proteins form a complex and then go into the nucleus and turn off those genes.

Those proteins are then degraded.

The genes are turned on again.

And so you have this, this cycle of protein production and degradation over 24 hours as a result of a feedback loop of an interaction involving these clock genes.

And we now know that subtle changes in some of those genes can be associated with morningness or eveningness.

I mean, one of the most extraordinary conditions is a familial advanced sleep phase syndrome.

Those people need to go to sleep at about 730 in the evening are waking up at four, five o’clock in the morning.

And it’s due to one tiny change in one of those genes that speeds up the whole clock.

So, part of our chronotype, our morningness versus eveningness, is actually due to our genetic makeup.

And I think that’s just extraordinary.

Now, it’s great having a clock.

And we’ve talked about the adaptive value of having a clock, this predictive ability.

But unless it’s set to the external world, it’s of absolutely no use.

A classic mismatch between the internal clock and the external world will be jet lag.

You eventually get over jet lag because of exposure to the light-dark cycle in the new time zone.

That’s the primary means.

There are other cues as well.

And so there are specialized light sensors within the eyes, different from the visual cells.

We discovered that you don’t need your visual cells to actually detect light from the eye, which regulates the internal clock, which has been really exciting.

And of course, the blind, their clock keeps on ticking.

And for most of us, our body clock is a bit longer than 24 hours.

And so what happens to them is that they spend the rest of their life almost like unremitting jet lag, getting up later and later and later each day.

And so these individuals with no eyes or radically damaged eyes have a double whammy.

They’ve got no sense of space because of course, they’ve lost their sense of vision, but they’ve also got no sense of time because those cells that would detect the light dark cycle are no longer there that would regulate the clock.

So a clock is a critical, but its adaptive value is only if you understand and know how light is so important in regulating that clock.

You know, there’s a lot of sort of old wives’ tales about certain things that get passed from generation to generation.

And there’s quite a lot of belief that the right thing to do is to get up early and go to bed early.

Do you think there’s something in that?

I get very irritated by that sort of thing.

You know, there’s this sort of idea that if you get up early, you’re virtuous.

And actually, it raises an interesting issue generally about the perception of sleep.

So, as we became more and more industrial and in the Victorian era, work was worthy and therefore to be embraced, because of course you can’t work when you’re asleep.

By definition, sleep was unworthy and therefore, you know, something to be despised.

And it is fascinating that we are now throwing off those shackles, but it still has that idea of the worthlessness of sleep.

And of course, it’s absolutely central to our ability to function during the day.

There’s an old wives’ tale that says all hours slept before midnight are worth double those slept after the clock strikes 12.

Or something to that effect.

Russell says that is nonsense.

You can sleep from 10pm to 5pm or midnight through to 7am.

It doesn’t matter as long as you’re getting the amount of sleep you require.

What matters is regularity and maintaining the schedule that works for you.

How much do you need to sleep?

I reckon at the moment I’m fine on 7, 7.5 hours and that’s what I tend to get.

I mean she would be happy I think with nine hours sleep.

And do you think those people who sleep more recover better?

It’s an interesting question.

There have been surveys which have suggested if you sleep longer than a certain amount of time or shorter, you’re at greater risk, health risks, for example.

There was a study published a few years ago showing long sleepers and short sleepers had a greater risk of early death.

The problem was with those studies is that they don’t assess the health status of the individuals.

They didn’t even assess BMI, for example.

So, of course, short sleep can be associated with illness.

So, if you have intractable pain, you can sleep very poorly.

And of course, long sleep can be confused with fatigue.

And of course, fatigue is very different from sleepiness.

So, sleepiness can be cured by sleep.

Fatigue cannot be cured by catching up with sleep.

And of course, long COVID is a classic example of that.

Even though you sleep much, much longer, you’re still feeling overwhelmingly fatigued.

And that’s very important distinction.

So, people are showing fatigue.

They need to contact their healthcare provider because that suggests there’s some underlying health issue.

And how important is it to get naps?

Napping is somewhat controversial.

What we know is that if you need to nap, you’re probably not getting the full amount of sleep that you need at night.

Having said that, again, I think the occasional nap is fine.

Let’s not get worried about it.

And, you know, as some people, again, worry about these things.

The data suggests that if you have a nap of around about 20 minutes, but certainly no longer than 30 minutes, you can gain a lot of benefit from a nap.

So, a nap around about lunchtime can mean that you’re much more viable during the second half of the day.

Where I do get concerned is particularly in youngsters and adolescents.

So, what happens is that they have shortened sleep for a whole variety of reasons.

They’re biologically more likely to want to go to bed later, then social media can make that even later still.

So, they can have short nighttime sleep, they’re driven out of bed by the alarm clock, they struggle for the school day, for example, some even falling asleep at their desk.

They then get home and have a two or three hours sleep, which is fairly close to bedtime, and that pushes back sleep pressure or the need to sleep that night.

So, you can get wrapped into a vicious cycle where you have shorter nighttime sleep, longer daytime sleeps or naps, and that can be very counterproductive.

But one of the things that in people, for example, in dementia or with other issues, are given sleeping tablets.

And the data there are quite clear is that it’s not sensible to take the benzos, the Z drugs and things, to try and induce sedation at night, because that can lead to daytime sleepiness and a real drop in the quality of consciousness.

And would you say that cumulatively or even one off is not?

I think the occasional, you know, and in fact, I think that the sleeping tablets occasionally can be very useful.

They can reset, they can recalibrate.

It’s where you become dependent upon them.

And I think, you know, medical practice these days is that you don’t prescribe long courses of, of sleeping tablets a few days, correct?

And then you need to use other sorts of things.

I mean, ideally, you know, you need to change behaviours that will promote sleep.

And it’s really important because these don’t provide a biological mimic for sleep.

And in fact, some sleeping tablets and certainly alcohol will actually sedate you but disrupt some of the important things going on within the brain whilst you sleep.

So, memory consolidation, for example, can be impaired by taking sedatives.

So again, the occasional is fine.

It’s where, and this happens a lot in our society where people regularly drink a lot in the evening to try and sedate themselves, thinking they’re going to get a good night of sleep, and actually the sleep they get is worse.

Yeah, it’s the old nightcap.

But I’ve noticed it just by using wearables.

The sleeping pill I take very, very, very occasionally, almost never.

But if I have a drink closer than two hours before sleeping, then I definitely see it in the sleep data I get in the morning.

And my deep sleep is definitely disrupted.

Sometimes it’s almost none.

And you see that in chronic alcoholics, they’ve lost all of their deep sleep.

And it takes a long time to get it back after they’ve withdrawn from alcohol.

It can be really quite serious.

And of course, what happens is that the waking day can be fuelled with lots and lots and lots of caffeine.

And of course, caffeine can last in the body a long time.

And so that has a big alerting effect.

So, you get to, you know, 10 or 11 o’clock at night thinking, “crikey, I’m completely wired”.

“I’m awake. I need to get some sleep”.

The tendency then is to drink a lot of alcohol.

And of course, you then disrupt your sleep.

So, you wake up in the, or you’ve woken up in the morning by the alarm clock.

You have more and more coffee.

And so that stimulant, sedative feedback loop can get really bad for, I think, for many of us without realizing you can slide into that state very easily.

With our modern lifestyles increasingly dominated by digital devices, understanding how screen time affects our sleep patterns is more important than ever.

That’s why I was eager to ask Russel for his insights on this critical issue.

So, screen use before bedtime.

I mean, the thing is, we talked about the importance of light.

And for humans, you need a lot of light for a long duration to get an effect, to regulate the clock.

So, for example, studies have shown that, yes, room light of 90 to 100 lux can have a mild effect upon the clock, but you need exposure for long durations, six to seven hours to get any effect at all.

So, it’s not that dim light doesn’t have an effect, it’s just that it needs a long duration.

Now, one of the classic studies that looked at this was looking at a Kindle, a light-emitting e-book.

And the experiment involved people looking at the e-book for four hours on its brightest setting immediately before bedtime, so between 6 p.m. and 10 p.m. before bedtime on five consecutive nights.

And in terms of sleep-wake timing, that after five days only delayed sleep onset by 10 minutes, and it was barely statistically significant.

So that really, and as one of my colleagues said, well, it may be statistically significant, but it’s biologically meaningless.

But from my experience, Kindle is very, very dim.

But the press was saying, you know, doctors say that if you read a Kindle before you go to bed, you’re going to disrupt your circadian rhythms.

The evidence for that is poor.

The other bit of data is where you’ve got these computer screens, which go from blue-enriched wavelengths to colours to red-enriched.

And there’s no clear evidence that that has any effect upon the sleep and circadian rhythm disruption.

So, we need a lot of light for a long duration to get an effect upon the clock.

Oh, yes, I should say, a more recent study has shown that if you’re getting adequate exposure to light during the day, bright light during the day, even subtle effects of looking at a Kindle before you go to bed are abolished.

So, for most of us who are exposed to reasonable levels of light during the day, we’re not going to be affected by dim light in the evening.

But would you put an iPad or a computer in the same category as the Kindle?

I mean, we don’t have all the data and I’m not saying that there is no effect, but I think the effect has been exaggerated, particularly if you’re getting bright morning light and you’re seeing light throughout the day.

So yeah, it’s a mild modulator.

And for many people, of course, a Kindle or something like that can be useful.

I mean, you know, reading a few pages of your favourite Jane Austen novel can relax you, and that could be useful in getting to sleep.

And for some individuals, that’s useful and important.

And we shouldn’t just have a bland statement of you must not.

But presumably, if you look at your smartphone and on there, you’ve got your Instagram, your Facebook, you got your BBC, you got your WhatsApp, you got your SMS, you got your email, you got the weather, the exchange rate, I mean.

And that’s why I would recommend not using these devices before you go to sleep, because they have an enormous alerting effect.

You know, just the moment the world is in such a mess.

And so just looking at the local sort of news or whatever can I think be very disturbing.

I think many of us struggle with wanting to be connected, whether it be emails or social media or whatever.

And many of us, including myself, are not often strong enough to not look.

So, I try not to have those devices next to me.

I asked Russel about what he’d recommend for restful sleep beyond reducing screen time and blue light exposure.

Yeah, the data on magnesium I was slightly sceptical about, but I was at a meeting fairly recently and there seemed to be some good new data suggesting the magnesium can indeed help sleep.

But sleep hygiene generally, it’s a big category of behaviours that stabilize sleep wake.

So, for example, an important element of sleep hygiene is morning light.

Of course, morning light helps set the body clock and therefore the sleep wake cycle.

Eating at the same time will reinforce that circadian stability.

Reducing, we talked about light and of course, light does two things.

It can change the body clock, it can shift the body clock, but it can also change alertness.

And so, very bright light before we go to bed can increase alertness acutely and therefore delay sleep onset.

So, a rule of thumb is to try and keep, you know, the lights relatively low.

One of the great ironies, of course, is what’s the last thing many of us do before we go to bed?

We look into a brightly illuminated mirror cleaning our teeth.

And I think there’s, in fact, I now know there are mirrors you can buy which have a night setting and a daytime setting.

So, in the morning you have nice bright light to increase alertness and dimmer light in the evening so you diminish alertness.

But I think one of the really important things to stress is that most people don’t have a sleep problem or a sleep issue.

It’s an anxiety or a stress issue.

And, you know, when mindfulness first surfaced, I think as a scientist interested in the mechanisms of sleep and circadian rhythms, I was somewhat dismissive.

And now I’ve seen some of the data whereby essentially mindfulness, which is a type of relaxation technique, put crudely, is very powerful in reducing individual stress and promoting sleep.

So those tricks of reducing anxiety are really important.

One thing that, you know, that’s getting off to sleep.

But what happens if you wake up in the middle of the night?

And many people think, oh my god, you know, I’ve woken up, I’m never going to get back to sleep.

I might as well start drinking coffee and do my emails.

But we now appreciate that human sleep, like all other mammals, is not a single consolidated block.

But it’s called either biphasic or polyphasic, which means, you know, you go down to sleep, you go through several non-REM cycles, you may then wake up.

And then you may not be conscious you’ve woken up, so you’ll fall straight back to sleep again.

But many people will become conscious that they’ve woken up.

And then they get terribly anxious.

But actually, this sleep, wake, sleep, wake, is what you see in societies that don’t have electric light.

And the wonderful studies by Roger E. Kirk has shown from historical records that biphasic sleep was often talked about.

And that people used to get up, interact in some manner, and then go back to sleep again.

So, the key thing is not to get anxious if you wake in the middle of the night, because it seems to be, broadly speaking, the default pattern that humans experience.

Well, I guess it’s easier said than done.

Yeah, you’re absolutely right.

But knowing that actually there’s nothing weird about waking up in the middle of the night.

And that if you stay calm and you go back to a few pages of Jane Austen or whatever that may be.

In my case, sometimes I listen to Radio 4 Extra, and there’s some wonderful, you know, Lord Peter Whimsy or something like that for 30 minutes, and I’m away.

You know, it’s interesting.

It’s those sort of warm, comforting programs that Radio 4 Extra has par excellence.

So just again, yeah, you probably will wake up, but it’s no big deal.

Just stay calm and you’ll go back to sleep.

It’s very interesting what you said about mindfulness, because we’re getting pretty good at keeping our physical bodies fit, but we’re not really very good at all at training our minds.

And I’ve only just really in the last six months properly engaged with mindfulness through someone called Sam Harris, who is a rather brilliant thinker and philosopher, but he has a meditation app, and I’ve only been able to do it because he explains it in a thoughtful, philosophical way rather than sort of the typical meditation.

And I think these are really important techniques, which we should include in the arsenal of cognitive behavioural therapy for insomnia.

The bedroom itself shouldn’t be too warm.

Part of going to sleep, and this seems to affect women more than men, is that there’s a drop in core body temperature.

And if you prevent that drop, it’s much more difficult to get to sleep.

So, the bedroom shouldn’t really be too warm.

And so, sort of 18 degrees, 17, 18 degrees, is probably the right sort of temperature.

The significance of sleeping in a cool room is something I touched on in my recent conversation with Davinia Taylor.

I mean, my sleep’s pretty good.

Eye masks, I’m really into, particularly in summer, because I like to sleep with the window open.

I just slept in a hotel last night without a window open.

It’s just given me horrible headache.

Yeah, it’s exactly the same.

You wake up with a hangover and you’re like, that is not fair, you know?

Everyone else is drunk last night and I feel worse than them.

So fresh air is just one of them.

And cold as well, cold temperature.

Absolutely, about 19 degrees is good.

Your body needs all these little things, just these natural hacks.

There’s something about habit as well, routine.

Another trick is don’t clock watch.

So many of us will have an illuminated alarm clock by the bed.

And again, it goes back to waking up and you look at the alarm clock and, oh my God, there’s only two hours before the alarm goes off.

You know, I may as well, you know, abandon it.

Get rid of it or cover it up because it’s not how long you’ve got before the alarm clock goes off.

It’s when the alarm clock goes off that’s important.

I’d be careful about taking sleep apps too seriously too.

At the moment, as far as I’m aware, none of the commercially available sleep apps are endorsed by the sleep societies and none are FDA approved.

They provide you with a measure of roughly when you went to sleep, if you woke up at night and when you finally got out of bed.

But their ability to detect REM versus non-REM sleep is very poor in many cases.

And, you know, you get this global score and yes, you had a good night of sleep or no, you had a poor night of sleep.

And that can be quite anxiety inducing for some people.

So don’t take the apps too seriously.

I think the Brits at least are a bit mean about their bedding.

I mean, 30% of our lives are spent in bed.

And yet, you know, we look at a mattress and we think, I’m not spending £300, £500, £1000 pounds on a mattress.

And of course, a mattress and bedding and decent pillows are really important.

And so, I would embrace those mattresses.

Another really important thing is what happens if you have a partner who snores.

Now, this is really controversial.

Well, not controversial, but it’s been, I talked about this quite a bit recently.

And clearly, you can use earplugs, but often they don’t work.

You need to make sure that your partner doesn’t have obstructive sleep apnea, which is this cessation of breathing and huge sort of gasping when you’re coming up.

That can be really quite dangerous, but it can be sorted out easily with these CPAP masks.

Or indeed, you can get some devices which can alter the architecture of the jaw.

But if they’re just a snorer and it’s disturbing you, it is of no shame and no reflection upon your relationship if you sleep in a separate room.

In fact, when I suggested this, people have said, oh, it’s the beginning of the end of the relationship.

And I said, no, no, it means you’ll stop feeling resentful throughout the night if your partner is waking you up snoring.

And then you’ll love them much more the next morning.

If you’ve had a good night of sleep and you can make a thing of it, you know, it’s you can bring in a cup of tea in the morning or whatever.

And sleeping apart, I think should be de-stigmatized.

If you get a better sleep, then embrace it.

What would you say is the most important pillow, sheets, mattress, everything?

I think it’s the combination that works for you.

You’ve got to be careful.

You may want to have a different duvet in the winter and the summer, because of course, a winter duvet can be too hot in the summer.

And of course, that’s a big problem we’re all facing, you know, particularly in continental Europe, of very hot nights and dealing with that is an issue.

And, you know, everybody says, well, just use a fan.

Well, fans can be potentially very useful because they can be cooling.

But if your bedroom, for example, isn’t clean, you can throw the dust around and it can cause, you know, dryness of the eyes, it can cause coughing and wheezing.

So, that can be problematic as well.

In my recent conversation with Matteo Franceschetti, an Italian entrepreneur and founder of Eight Sleep, he emphasized the critical role of body temperature in achieving quality sleep.

There are three pillars in our health.

One is sleep, one is nutrition, and one is fitness.

So, these are the three pillars of health, and you need to take care of all of them.

The interesting thing is that sleep comes first, because if you start sleeping two hours per night, then you’re not going to be able to work out to today and probably you will eat junk food because you’re in craving mode.

So, while there are three pillars of health, the foundational part is really sleep.

So, our body temperature changes during the night, right?

And so as soon as you fall asleep, your body temperature will drop, it will keep going down, and three, four hours before you wake up, it will start rising again.

It kind of follows the sun.

So, imagine if we go back 2,000, 3,000 years ago when we were still living in caves, right?

You go into the cave, the cave gets colder and colder in the middle of the night, and then as the sun starts coming out, it gets warmer.

So, this is what is already happening, and this is what is called circadian cycle.

So, Eight Sleep is not reinventing the wheel with these temperature changes.

It’s something that your body is already supposed to do.

We just help your body to do this job better and faster and at the right time.

Then specifically for the different sleep stages, when you are in deep, you usually need a colder temperature to maximize your deep sleep, while instead in REM, you need a neutral temperature.

Neutral because REM is when your body gets paralyzed because you’re going to dream, and so the body doesn’t want you to go around or to start moving in your dream.

It doesn’t let you fall into REM unless this temperature is neutral.

Otherwise, you could die during that phase.

Imagine that it was too cold, and you get into this REM, your brain is not going to let you fall into REM to protect your survival.

And so, what we want to give you is this colder temperature in deep sleep and neutral temperature in REM.

The thing you should know is that our sleep cycles are 90 minutes.

And so every 90 minutes you have light sleep, deep and REM and then you restart.

And so we need to make this adjustment continuously multiple times during the night.

Let’s talk about this a little bit because I’ve had Professor Russel Foster on this podcast who is a Professor of Circadian Neuroscience at Oxford.

And we talked a little bit about debunking these myths about getting up early, being very good for you.

Because what’s actually most important is the circadian rhythms is not what time you go to bed and what time you wake up, but it’s that you do it consistent.

Yeah, consistency is key in your sleep and is one of the areas where I try to put more attention personally.

Because you train your body, right?

You train your body to fall asleep a certain time and you train your body to wake up a certain time.

And one example I always give is I don’t have kids yet, right, but I have a bunch of friends with babies and kids.

And if you look at how regular and consistent we try to be with our kids, in particular with babies, right, then we lose that approach when we are teenagers and in our 20s or early 30s.

But that same framework should apply to us as adults, as it applies to babies and kids.

Sleep is so personal, that is probably what is the most misunderstood thing of sleep.

Sleep is so personal, right?

And there are people that like to read before going to bed.

Well, instead, for example, for me, it reactivates my brain.

Because most of the times I read business books, and if I start reading a business book, then I start thinking how do I apply that to my business?

There are other people that they can fall asleep immediately, and others know that they need a long time.

Obviously, it changes based on gender.

It changes a lot based on age.

In our 20s, you can drink, you can go to sleep late.

I mean, you can do whatever you want, and more or less, you still have a pretty good sleep architecture.

But as soon as you start crossing, probably 35 years old, that is when you start seeing the impact of alcohol and food and digestion.

And so everything needs to be personalised based on your age, gender and your genes.

I was intrigued to find out why Eight Sleep’s, innovative bed cooling product, is considered better than any other devices and sleep aids.

So, compared to wearables, first, you don’t have to wear anything, right?

You go to bed as you did for the rest of your life, but this time you will get better sleep.

So, nothing to wear, nothing to charge.

That is the biggest advantage.

The second biggest advantage is also that, because we have so much space, we can have way more sensors and we can be way more accurate.

But all in all, our, I would say, magic sauce is the AI that we use behind the scene, and based on your biometrics, we automatically adjust temperature in real time to give you better sleep.

So all the wearables, they can tell you what you should be doing, but they don’t do the work for you.

Eight Sleep does the work for you while you’re asleep, we change temperature, and magically you get better sleep, or you stop snoring.

I also asked Russel about the common misconceptions and myths that surround sleep.

There are some data showing that really late chronotypes have a greater association with mental health problems.

But that, I think, is again difficult to disentangle cause and effect there.

But certainly, you know, the worthy morning riser is, for me, a major myth.

There’s no greater virtue of being up earlier than somebody else who likes to sleep in.

It’s all about getting the sleep that you need as an individual.

Cheese, before sleep gives you nightmares?

I don’t think there’s any evidence that it does cause nightmares.

I think there were some studies a few years ago which suggested not.

It can cause digestive issues.

So, there might be some stomach issues.

But I don’t think, I suppose, it only just occurred to me.

I mean, if you’ve got a bit of a digestive issue, then possibly you might wake up and you might wake up during REM sleep or after REM sleep.

And of course, that’s when you have your nightmares and your dreams.

And so perhaps because of the cheese’s effect on your digestion and that may wake you up, you then wake up during REM sleep and you remember your dreams.

Maybe that’s the origins of the myth.

But I don’t think there’s any clear data suggesting that cheese will induce dreams.

Horlicks, would it help you sleep?

Well, you see, that’s interesting.

A hot milky drink, there’s a lot of psychology there and a lot of people associate a warm drink with part of the winding down and sleep process.

Whether it does have an effect is interesting.

I mean, there was a thing a few years ago where you could buy milk, milk from cows at night because the milk had melatonin.

Well, this is wrong for a whole range of reasons.

One is melatonin is not a sleep hormone.

It’s a very mild modulator of sleep.

And you often read in the press, we go to sleep at night because melatonin is high.

It’s, as I say, it can help, but it’s very mild.

It is not the driver of sleep.

So, my feeling is that I think warm drink of some sort is probably comforting.

And it may be part of the ritual whereby you know you’re sliding into the sleep state.

Presumably chamomile tea does.

Yeah, there’s some evidence that chamomile can be helpful.

Exactly how effective it is isn’t clear.

And again, more studies need to be done.

Does counting sheep help you sleep?

Well, anything that is sort of kind of repetitive and sort of takes you from thinking about the worries of the day, then I think could probably be effective.

And it does work for some.

It doesn’t work for me because I start thinking of different sort of numerical formulations and I just sort of deconstruct the counting into some sort of mathematical process.

I think, “my God, this is crazy”.

In a recent conversation, Rita Ora highlighted the importance of finding your own nighttime routine and how finding what works for you can be transformative.

Sleep is a very big, big deal for me now.

God, I can’t believe I’m saying that, which we don’t get enough of because of what I do when I travel and fly and my jet lag is horrible.

Why do you say you can’t believe?

Were you not, before, were you not really?

No, I just didn’t, you know, you don’t need it when you’re young.

I don’t go to sleep at the same time all the time, you know.

Last night, I went to bed at 1 a.m.

I was on the phone, and I was dealing with things, but I still made sure I got my hours in.

And luckily for me, I was able to do that.

You know, some people don’t have the privilege of doing that and they have to go to work every day at the same time.

That’s why I’ve made it like a ritual.

I find that really helps me, you know, putting on the pillow mist and putting on music and giving space for me to read for like 30 minutes.

And I’ve become like it’s a ritual for me now.

So, it’s become like a way I do the same thing every night.

So, that helps me a lot to fall asleep because I still struggle to fall asleep because my brain is like all the time.

Because I’m the opposite.

I mean, I fall asleep like this.

But if my brain is busy, I wake up at kind of six, seven and then the switch is back on.

Yeah, me, I don’t fall asleep.

Yeah, some people shut down when they have a lot happening and then they get up and get on with it.

Now, I can’t seem to shake it off.

It’s strange, but I fall asleep.

In our modern society, we’ve evolved to prioritise productivity and constant connectivity, often neglecting the essential need for sleep.

Despite its crucial role in our health and well-being, sleep has taken a back seat in our busy lives.

And I wanted to ask Russell for the reasons behind this.

Yeah, the key thing, of course, is that with the advent of cheap electric light, from the 1950s onwards, both domestically and in a commercial setting, we as a society were able to invade the night.

And the first victim of that invasion was sleep.

Because we could invade the night, we felt we should.

And we abandoned, within a very short period of time, any appreciation of the value of sleep.

It is quite extraordinary.

I mean, part of the great strength of our species is that we do have this extraordinary arrogance, that we can do whatever we want at whatever time we choose.

And of course, electric light and light in the evening allowed us to do that.

And we now, in a sense, need to take back the night and embrace the dark and appreciate its value for our well-being.

Yes, it seems like it’s got a very, very high value.

We talked a little bit about sleep and culture and arts.

Is there an artwork or a piece of music or a piece of writing that for you signifies sleep?

I’m very much moved by music.

And of course, the concept of dreams and sleep in the ring cycle, for example, are very profound.

And so, I think Brünnhilde’s Being Put to Sleep on the Rock of Fire by Wotan is one of the most beautiful pieces of music, I think, that humanity has ever created.

Of course, it was it was created by a monster, Wagner, who was not a nice person, but for some reason or another, he managed to produce the most sublime music.

So, I think the way that sleep and dreams have been depicted increasingly, well not increasingly, but throughout music have been very influential on me.

Well, it’s a wonderful note to end our conversation, Russel, Professor Foster.

Thank you for coming on Brave New World, and I really enjoyed that conversation.

Thank you so much for inviting me.

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