Sleep can enhance your creativity, lift your spirits, improve your sense of humor, and amplify your sociability. So why do so many of us struggle to get a good night’s rest? Russell Foster, a professor of circadian neuroscience at the University of Oxford, says it’s because we’ve let the frantic drumbeat of modern life drown out the steady tick-tock of our biological clocks. That’s the bad news. The good news is that Russell’s here to share science-backed tips that will have you catching more z’s in no time.
Listen to Russell’s appearance on the Next Big Idea podcast below. If you want to listen to this and other episodes ad-free, and enjoy hundreds of audio summaries of the best nonfiction books, written and read by the authors themselves, download the Next Big Idea app.
Don’t get eight hours of sleep every night? Don’t worry.
Rufus Griscom: Well, Russell, I have to ask you on the front end — how did you sleep last night?
Russell Foster: Actually I slept quite badly last night, which is not characteristic. Normally I sleep very well indeed. Last night was a bit of an anomaly.
Rufus: What’s the minimum that you need to feel like you’re functioning well?
Russell: I can function optimally between seven and eight hours. Of course there’s lots of individual variations. Some people can function perfectly well on six hours, other people may need 10. And I think it raises a very important point. Sleep is like shoe size: one size does not fit all. And part of the reason for writing Life Time was because I was getting a little bit irritated with the sort of sergeant majors of sleep screaming, “You must do this and you must do that!” You know, the mantra that you must get eight hours. Well, that’s an average, but some people are perfectly fine on less and some absolutely need more.
I was asked before lockdown by a chap who said to me, “I don’t get eight hours of sleep. Am I going to die?” And I said, “Well, yeah, I can guarantee you’re going to die, but it may have nothing to do with the fact that you’re not getting eight hours of sleep.” We need to assess for ourselves whether we are getting sufficient sleep to allow us to function optimally during the day.
The dire consequences of poor sleep.
Rufus: Having read your book, Russell, I feel like I know you to some degree, and I believe you’re a “glass half full” guy, as am I. It may not be in our nature to scare people, but I think it may be helpful, as a public service, to just hit people straight up with how profound the negative impact of inadequate sleep can be.
Russell: I think we can divide the impact of not getting enough sleep into two domains.
One is the acute impact of not getting sleep, which is what we all experience. If we think about these short term effects, many of the things that make us human are affected. We see fluctuations in mood and what’s called a negative salience—it’s been shown that the tired brain remembers negative experiences but forgets the positive ones, so if you’re tired, your whole world view is being biased by those negative experiences. You get feelings of irritability and anxiety when you’re tired. Loss of empathy—this is such an interesting one. You’re failing to pick up the social signals of your family, friends, and colleagues, and you show increased levels of frustration, risk-taking, and impulsivity.
The tired brain seeks stimulants, such as caffeinated drinks, to try and keep it going throughout the day, but that’s also associated with sedative use at night, so tired people drive the waking day with endless cups of coffee, and then, of course, caffeine lasts in the body for some considerable time, so they think, Oh, goodness, I’ve got to get some sleep, and they sedate themselves using alcohol. And, of course, alcohol can actually impair some of the important things going on in the brain whilst we sleep, like memory consolidation and the processing of information to come up with innovative solutions to complex problems. Some beautiful science has shown that a night of sleep can genuinely enhance our capacity for creativity.
“Those wonderful things that make us this very special animal have been blasted by a lack of sleep.”
Whilst we’re asleep, the brain is not turned off. It’s laying down memories and processing information. Those wonderful things that make us this very special animal have been blasted by a lack of sleep.
And that’s just the short term stuff. If we think about the longer chronic impact of sleep on our physiology and health, we now have very good data showing that night shift workers, for example, or the business community, where people are getting very little sleep during the nighttime, we’re seeing cardiovascular disease really increasing. Altered sensory thresholds—so feelings of coldness, strange stress responses. You’re pumping out much higher levels of the stress hormones cortisol and adrenaline. That may be associated with increased levels of infection and lowered immunity, and that may be connected to the higher rates of cancer. The World Health Organization has now classified night shift work as a probable carcinogen because of the studies correlating high rates of cancer with night shift work.
And a really important factor is that if you are vulnerable to depression or psychiatric illness, poor sleep can slide you into a more pathological state.
I think the really important point here is that poor sleep is not just feeling tired at an inappropriate time. It’s having massive impacts upon our emotional and cognitive health, our physiological wellbeing, and our mental health. So, yeah, it’s really important.
Why do we sleep in the first place?
Rufus: How is it that our need for sleep evolved to begin with? Why do we have to surrender eight hours of our lives every day?
Russell: Let me give you my theory for sleep. I published this paper a few years ago and, with the advice of the editor, the title got changed to “There Is No Mystery to Sleep,” which, of course, has irritated some of my sleep colleagues incredibly. If I can try and summarize, the argument is essentially that almost all life on the planet has had an evolutionary response to the earth rotating on its axis and producing a day/night cycle—a period of light or dark, warmth or cold, and all the rest of it. What life has done is evolved specializations to allow us to cope optimally when you are active or inactive, because you can’t be both.
Think about the specializations that owls have to allow them to function at night. They’re completely different from birds who function during the day. And that’s true for nocturnal and diurnal animals generally. If you put them in the wrong part of the day—take a night animal and put it during the day—they usually fail very badly.
“What life has done is evolved specializations to allow us to cope optimally when you are active or inactive, because you can’t be both.”
So once you’ve made the evolutionary decision to become day active or night active, then you need to avoid moving around within an environment to which you are poorly adapted, and once you’ve made that decision to be active or inactive, you will portion your physiology accordingly. So for us, we have all this information flooding in during the day, so what we do is we park it, and then we process it offline. When we’re inactive, we’ve got the capacity to start to play with that sensory information, consolidate it to memory, and turn it into creative ideas. Similarly, if we’ve been metabolizing stuff during the day, we then need to package up some of the toxins at night.
So my definition of sleep would be a period of physical inactivity preventing you from moving around within an environment to which you’re poorly adapted, but during which time you undertake critical biological processes.
How to become a morning person.
Russell: Morning light advances the clock, the sleep/wake cycle. It makes you get up. Evening light does the opposite. It makes you go to bed later and get up later.
We did a study of university students around the world a few years ago, showing that the later the chronotype—the more owl-like an individual was—reflected the fact they didn’t get much morning light, which would make them get up earlier, but they got lots of late afternoon light, which would push them to a later stage.
So if you happen to be a late type and you need to be more of a morning type, you can set the alarm, either sit in front of a light box or go outside, preferably get that morning photon shower, which will advance the clock and make it easier for you to get up earlier and go to bed earlier.
Russell’s tips for getting a good night’s rest.
During the day:
- “Get that photon shower, that morning exposure to light. And it’s very important to appreciate that those specialized cells need bright light, the kind of levels that you get outside, so several thousands of lux, not room light, which is 100–300 lux. So get outside or get a bright light box.”
- “If you nap during the day, make sure it’s not longer than 20 minutes and not within six hours of bedtime.”
- “We’ve shifted our eating massively. In 1100, the main meal of the day was breakfast. By the 1500s, it had shifted to 12 o’clock. And then we had the Industrial Revolution. People were rushing off in the morning, didn’t have time for a decent breakfast, and certainly weren’t coming home for a big lunch, so when they finally got home in the evening, they’d eat massively before bedtime. That has been shown to increase your chances of type 2 diabetes and obesity. And, of course, those problems increase sleep problems. So try and concentrate your main calories during the first half of the day.”
- “Step back from stressful situations. I think many of us would argue that most people don’t have a sleep problem, they have a stress or anxiety problem. So do find ways of de-stressing towards the end of the day. That might be going to the gym, for example.”
- “Keep the light levels low 30 minutes before bedtime. The brighter the light, the greater the alerting effect that light will have. And the more alert you are, the more difficult it is to get to sleep.”
- “Stop using electronic devices 30 minutes before bedtime. That’s tricky, I know, but get the televisions out of the bedroom and stop using your smartphone.”
- “I used to be very, very snooty about mindfulness. I put it in the same box as crystal waving. But then I looked into it, and actually it’s a great relaxation technique.”
- “The bedroom itself shouldn’t be too warm. It should be quiet, and if it isn’t, you could use white noise or some relaxing sound such as the sea. Keep it dark. Blackout curtains can be quite useful.”
- “Keep a good routine. That’s really important.”
- “I don’t know about Americans, but Brits are a bit mean about their bedding. I don’t think we realize that 30 percent of our lives will be spent in bed, and we’re a bit cheap about mattresses and pillows and things. It’s worth investing in a gloriously comfortable mattress and pillows.”
- “If your partner snores, then try earplugs. Now, many people can’t hack earplugs, and my advice here is to find an alternative sleeping space. This is not a reflection on your relationship. It just means you get a better night’s sleep and the wake time that you have together will be better. You’ll have a better sense of humor. You’ll enjoy each other’s company more.”
- “If you wake, stay calm. We are all taught that we’ve got to have eight hours of consolidated sleep. Nonsense! There’s strong evidence, both from the lab and from studies of literature, that the natural sleep pattern of humans, like all other mammals, is: you’re asleep for a while, you wake up — you may be conscious that you’ve woken up or you may not — and you fall back to sleep again. You go through a series of sleep/wake cycles. The key thing is that if you do wake, it is not necessarily the end of sleep. Many people will wake up in the middle of the night thinking, Oh my goodness, that’s it. They’ll abandon sleep, start drinking coffee, looking at my emails. Whereas if you stay calm by lying in bed or going to another room, keeping the lights low, listening to some relaxing music, reading a few pages of your favorite novel, you’ll feel tired, and then you’ll go back to sleep again. It’s so important to appreciate that waking up in the middle of the night is not necessarily the end of sleep. It’s a natural process and we mustn’t get stressed about it.”
To enjoy ad-free episodes of the Next Big Idea podcast, download the Next Big Idea App today: