Hi, I'm Jonny Dymond and from the BBC World Service, this is The Global Story.

Tossing, turning, feeling wide awake at two in the morning and struggling to get back to sleep?

We know how bad we feel after not getting a good night's rest.

We spend around a third of our lives asleep, but a third of us regularly struggle, and recent research shows that bad sleep can increase the risks of multiple health conditions.

How harmful is it to get insufficient or irregular sleep?

And given how common it is, can it be improved?

With me today is Russell Foster, professor of circadian neuroscience at the University of Oxford.

Hello, Jonny. Nice to be with you.

And Dr Nerina Ramlakhan, a physiologist and author.

Hello, Jonny. Lovely to be here.

Let me start with the most important question of the day.

Nerina, how did you sleep?

Smugly, I have to say, I slept beautifully last night.

I celebrate good nights of sleep because for many decades I didn't sleep well.

Russell. How did you sleep?

Actually, extremely well.

I woke up once and then got straight back to sleep again, so all good.

Two very smug guests in our studio.

Delighted with their sleep.

Russell, you specialise in circadian rhythms.

Some people watching and listening may know what that is, others will not.

What are they?

And I suppose why are they so important?

So if we think about what our biology needs to do, it has to deliver the right stuff at the right concentration, to the right tissues and organs at the right time of day.

And what our circadian system allows us to do is give a time structure for our entire biology.

And so it's an internal representation of a day, which is fine tuning every aspect of our physiology, every aspect of our biology, to the varying demands of sleep, activity, consciousness and sleep.

And the critical question, I suppose.

Well, for for ordinary punters like me.

What does the clock recommend or mandate even as an optimal amount of sleep?

I've often said that sleep is like shoe size.

One size does not fit all, and there have been some somewhat irresponsible sort of statements saying if you don't get eight hours of sleep, you're going to die.

Well, that's just nonsense.

I mean, the healthy range for sleep from the National Sleep Foundation, which I'm a member of that board, is somewhere between six hours, and it may be up to 10 and a half, even 11 hours.

For some people, the average, true, is about seven to eight hours.

But there's lots of variation between individuals.

Nerina, you have spent what, three decades helping people to get better sleep?

I think it's ranged from what, schools to psychiatric wards?

What do people tell you causes their poor sleep?

Sometimes people have these really unhelpful beliefs, these misconceptions about what they should or should not be getting.

And, they go around saying, I've got this amount of sleep and they're measuring it and they're obsessing about it.

And that in itself is creating problems with their sleep.

It's creating anxiety.

So I think that there's that side of things, but there's also what I've been observing for the last 30 years.

I started doing this work in the 90s.

I left the academic world and ended up in a health screening clinic where I was measuring the health of city professionals.

And that's when I started to notice that more and more people wanted to talk about sleep.

And at the same time, of course, technology had exploded onto the scene, the internet and mobile phones, and everything was going really fast.

So I've been paying attention to the speed and noticing how it impacts our human physiology.

And as Russell has said, you know, the circadian timer and and then how it impacts sleep and I think that's playing its part, the speed of life.

How does that play a part?

I mean, I understand things that feel like they've got a lot faster.

Does it mean in your eyes that we are unable to slow down into sleep, because we are spending so much more of our lives in a sort of heightened state of existence?

That's a very good way of putting it, yes.

We've certainly lost the ability to slow down.

We've lost the ability to oscillate.

I love that word that Russell's used.

But not just at night, but throughout the day, oscillating all of the physiological processes in the body.

They oscillate in a kind of sinusoidal up and down rhythm.

And I think the way we're living our lives, we've become very restless.

You know, I remember the good old days.

I don't want to give my age away.

But when we had lunch breaks and coffee breaks and tea breaks and people don't, they're so stretched to the limit.

So we thought technology would make life easier.

And it does in many respects that we can do this sort of thing.

But it does mean that people are stretching themselves and often against the limits of their physiological capabilities.

Nerina, you mentioned this sort of irony that people, some people, at any rate, are now getting so anxious about sleep that it's affecting their sleep.

It leads inexorably to the question, how can you tell when you're not getting enough sleep?

Well, I try to encourage my, my clients, and you've mentioned some of them.

They might be children in schools.

They could be people in psychiatric clinics.

But a lot of corporate employees.

I try to encourage people to listen more deeply and to not reach for their phones or their devices first thing in the morning to see what an app has just told them, but actually to just when you wake up in the morning, before you reach outside of yourself to be told X, Y, or Z, just listen.

How do you feel right now?

How do you feel?

And even to listen to the speed of your breathing or the speed of your thoughts?

And then as you go about your day to pay attention to how the body feels physically, how you feel emotionally.

How are you relating to other people?

Russell? I see you nodding along.

Yeah, I think it's a really good point. I completely agree, and I think many people fundamentally don't have a sleep problem.

They have an anxiety or a stress problem.

And sleep anxiety is now recognised as an issue and it arises for lots of reasons but it means we have a target.

There are things that one can do about reducing one's anxiety, either before you go to bed, before you go to sleep, or if you happen to wake up.

There are anxiety reducing regimes that you can adopt to get back to sleep.

And I think an increasing understanding of why you might be having sleep anxiety is really important going forward.

Russell, I want to ask you about whether or not sleep as a block is important.

I mean, I think a fair number of people watching or listening to the show will wake up during part of the night and then hopefully get back to sleep, but worry that somehow the second bit of sleep is not worth as much as the first bit of sleep. Are they right?

Well, I would argue very strongly that it doesn't matter if you wake up in the middle of the night, as long as you've got the techniques of reducing stress and getting back to sleep.

And we've been so often told that the perfect sleep is an eight hour single block, and that's simply not the case.

As one ages, you're more inclined to have what's called biphasic sleep, whereby you're going to sleep, you're waking up, you're going back to sleep again, or indeed polytheistic sleep.

And historically, there are some studies which suggest that this may be the default pattern of human sleep.

And the key thing is that if you do wake up in the middle of the night, the tendency is to think, oh my God, you know, that's it.

I might as well start drinking coffee and doing emails.

And if you lie there and you relax, you'll almost invariably get back to sleep.

Nerina, we've talked about anxiety over sleep, and part of that anxiety is that people don't want to be exhausted during the day.

Another part is because of their concern that bad sleep is bad for you in both the medium term and the long term, are they right?

And if they are, how do we know that it is bad for you?

What aspects of our health get affected by it?

Yeah, there's certainly research that shows that we can become more prone to disease risk.

And I can see Russell's nodding as well.

But you know things like heart disease, diabetes, weight gain.

Our physiology is a complex interplay of all these hormones and neurotransmitters that are beautifully controlled by the levels of light and dark.

But when people are working against these rhythms, it starts to affect our physiology.

And if that goes on for a chronic period of time, it can start to affect our health.

And as we get older, and if you look at shift workers, the impact, you know, disease risk and shift workers is well documented, particularly as they get older, past the age of 35, 40, disease risk increases.

And when I worked in the psychiatric clinic, I started to see the impact on mental health, people presenting with anxiety and depression, even eating disorders and addictions and the poor sleep is kind of all wrapped up in there as well.

Sleep is the golden medicine, but it's also one of the things that can fall by the wayside if people are feeling unwell and mentally unwell.

We produced a model a few years ago suggesting that yes, at the core there's an overlap between the fundamental mechanisms in the brain that are generating normal sleep and those that are generating normal mental health.

I mean, key neurotransmitters.

So that if you have a change in a neurotransmitter that predisposes you to a mental health condition, it's almost certainly going to have an impact on sleep at some level.

But the key thing is the poor sleep, because of its impact on our cognition, our emotional responses and our physiological responses can make the mental health condition worse.

And poor mental health can feed back and make the sleep worse.

So we did some experiments a few years ago on individuals who were on the psychosis spectrum.

This was led by Dan Freeman, whereby we were able to partially stabilise sleep.

And what was so wonderful is that you were able to reduce the levels of paranoia and the hallucinatory experiences.

So there's an absolute link between poor sleep and levels of of mental health severity.

Russell, what about mental degeneration?

Because there has been talk of a link to dementia.

I mean, there's been a long sort of correlation that poor sleep in the middle years is associated as a risk factor for dementia in the later years, and there's never been a really satisfactory explanation for that until recently.

And there's been a recently discovered system within the brain called the lymphatic system, which clears out toxins and misfolded proteins, one of which is beta amyloid, and build up of beta amyloid - which is like chewing gum, sticking in cells and making them not work very well - a buildup of beta amyloid has been associated, of course, with dementia and Alzheimer's.

Now the lymphatic system is turned on whilst we sleep and actually is clearing out some of those misfolded proteins and other toxins.

And so it could be, and this is all correlation at the moment, that poor sleep in the middle years affects the lymphatic system, and that predisposes you to some of these degenerative conditions.

I want to turn, if I can, to the impact of both the lifestyles people lead and also where they live in terms of how much daylight they see.

It's really about the impact of less daylight upon people and whether it changes how much sleep they need or that they feel they need.

Russell, has there been research into this?

Yes, quite a bit.

We've done some and there are many labs around the world.

So basically what the circadian system needs to be of any use at all is to set the internal clock to the external world.

And the most important daily signal is the light dark cycle.

And so morning exposure to light especially is really important in setting the clock.

How much have you worked with night shift workers and the impact that their work has on their sleep patterns and their health?

Quite considerable amount actually, I have done quite a bit of work in the past with police services, other emergency services, hospital workers and helping them to manage those shifts and to manage their rest when they're working shifts and when they come off shifts, it's a really important consideration because there are so many health implications of working shifts and missing out on those crucial kind of hours of sleep that they should be getting at night.

I mean, is it as unhealthy as we are now led to believe?

The levels of light and dark and the way that impacts the health, it impacts our physiology and night shift workers, shift workers are very prone to not just physical ailments.

They can be prone to mental health, emotional and and even the social implications.

I think the divorce rate...

in fact, I was married to a shift worker.

Right. Past tense.

But it has implications for health, relationships.

And what's interesting, I think, is that the assumption by employers is that people will adapt to the night shift work, and they don't.

And the reason they don't is because of light.

So they're under relatively dim light in the workplace at night.

Then we'll be exposed to natural light during the day, and the clock will always defer to the brighter light signal as being daytime, which it is.

So in a sense, what you're doing is having to override this entire biology, saying you should be asleep.

And one of the problems, of course, is that you override it by activating the stress axis.

And as we know, sustained stress activation distorts our physiology.

One aspect that gets hit is our immune system.

So nightshift workers are more vulnerable to infection and indeed cancer.

So the World Health Organization now has designated nightshift work as a probable carcinogen because of the higher rates of colorectal cancer, breast cancer that have been documented in nightshift nurses.

I want to talk about solutions very much because I don't want the audience to walk away desperately depressed by the whole thing.

Your top tips if you would for sleep.

And I want to hear from both you, Russell and Nerina, start with you, Russell. Your top ideas for, I suppose, the relatively simple things that people can do.

I think making sure you're getting morning light to stabilize the circadian system and making sure that you're winding down and you're de-stressing, whether that be exercise or whatever before you go to bed.

There are other things I think that one can factor in.

And I sort of talked about this fairly recently, that if your partner snores, for example, or you find difficulty sleeping in the same space as your partner, obviously you would have checked that they haven't got obstructive sleep apnea, but it's not an indicator of the quality of your marriage if you sleep in separate rooms.

And I know a lot of people have real problems with that concept, but actually it's not the end of a relationship.

It's the beginning of a new one.

You'll be more refreshed, you'll be happier, you'll have a greater sense of humour, and you can turn it into who's going to make the tea in the morning type stuff.

So I agree with everything Russell has said.

There we go. Of course, that's good.

Especially I love the one on, you know, negotiating separate caves as well.

I think that's very important.

So these are the five things that I recommend to my clients with the clients, patients and a version of this to school children as well.

And athletes, all of them, these five things, what they do, 10 to 14 days of doing these things, I have noticed they start to reset the nervous system from this highly activated stress side to this more restful sleep accessing part of the nervous system.

Okay. Have I sold it?

I'm gasping for it. I can't wait.

Okay. Number one, eat breakfast in the morning.

Don't skip breakfast.

So eat within about 30 to 45 minutes of rising.

Big thumbs up from Russell. Okay. Thank you.

So, number two, don't use caffeine as a substitute for food.

Eat first, then have your coffee.

That's what I did this morning.

Ideally no more than one or two a day.

Ideally no caffeine after midday.

I would say number three, make sure you're well hydrated.

Number four, get to bed earlier.

So I recommend that people start preparing to go to bed around 9:30, 10:00ish.

I don't mean get into bed and be asleep, but get into your lovely haven of a bedroom and be restful.

You could be reading a book, you could be meditating, you could be journalling.

This is about sort of advising your body that it is bedtime.

Yes, and finding that sweet spot for restfulness which will enable you to kind of access then those deeper phases of restoration.

Number five, stop flooding the brain with the wrong kind of light at the end of the day.

So Russell talked about getting light in the morning, the light shower in the morning.

But similarly we need to pay attention to how we're misusing light at the end of the day.

What's the wrong kind of light?

Blue light from your phones, your electronic devices.

The activating effect that they have on our sleep.

It's the doomscrolling and and all the rest of it.

And so that's actively different from reading a book?

Well, actually the initial study suggested that it was.

It is, yes. When we're reading a book, the eyes. If you're reading a paper book, your eyes are moving almost in a hypnotic way from left to right.

Often when people are reading on a screen, and even if it's one of those light corrected screens, you know, they're sort of reading almost in a question mark.

You know, the eyes start to speed up and speed reading.

But as Russell said, it's that doomscrolling and what we put into our minds before we go to bed has an impact on where we reside in the nervous system.

And at the end of the day, when the hunter gatherer feels safe, the hunter gatherer sleeps.

If you're doomscrolling, if you're looking at the news, if you're looking at the dating sites telling you that no one loves you, if you're looking at share prices, if you're looking at all your emails and what's going to hit you the next day, that doesn't make you feel safe.

We will leave it there.

Russell, Nerina, thank you so, so much for both your analysis of what has been going wrong and your suggestions of how things might go right.

Thank you very much indeed.

Great pleasure. Great pleasure.

And thanks so much to you for watching.

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