Matthew Walker’s bestselling ‘Why We Sleep’ is an eye-opening account of how we’re missing out on the number-one, life-extending and enriching thing we can do for our wellbeing. Sleep is free and we do it every day but fully two thirds of us of aren’t getting the recommended eight hours, a habit that’s as damaging as smoking or regularly drinking to excess.
Get it right and over 17,000 well-scrutinised scientific reports say that it enhances your memory, makes you more creative, makes you look more attractive, keeps off bodyfat, cuts cravings, protects you from cancer, lowers risk of heart attacks and makes you happier – here’s what RSNG learned about the new science of sleep and dreams…
The Sleep Questions You Need To Ask Yourself Life is busy – that’s so true that it’s become a universal cliche. When you’re striving to do more, everyday, the first thing that gets chopped is sleep, so being chronically sleep deprived has become the new normal. Matthew Walker says there are some questions we all need to ask ourselves: ‘If you didn’t set an alarm clock would you sleep past that time?… After waking up in the morning, could you fall back asleep at 10 or 11am?… Could you function optimally without caffeine before noon? If the answer is “no,” then you are most likely self-medicating your state of chronic sleep deprivation.’
Caffeine Kills Sleep Pressure There are two things that make us sleep: our 24-hour circadian rhythm and the daily build up of a chemical called adenosine in our brains. The longer you spend awake the more adenosine builds up, creating sleep pressure, which becomes irresistible after 12-16 hours. As Matthew Waker points out, caffeine acts as a chemical mute button for adenosine and sleepiness, and its use (and abuse) is a massive, unsupervised drug experiment on the whole human race.
What’s more, caffeine has a half life of 5-7 hours, so drinking a cup of coffee after a 7:30pm evening meal will leave 50% of it buzzing around your brain at 1:30am. ‘Sleep will not come easily or be smooth throughout the night as your brain continues the battle against the opposing force of caffeine,’ writes Walker. Even worse news is that many of us are genetically sensitive to caffeine, because our livers use a slower-acting enzyme to break it down.
We’re Not Sleeping As Nature Intended Walker has looked at all of the available evidence, from studies of pre-industrial hunter gatherer humans, to current biological and genetic analysis and has come to a startling conclusion: we should all take daily naps. He says that biphasic sleep is the natural standard humans evolved to do best on, which means: ‘The true pattern of biphasic sleep… is one consisting of a longer bout of continuous sleep at night, followed by one shorter mid-afternoon nap.’ As an example he points to a Harvard University School Of Public Health study on 23,000 Greek people stopping their siestas, which found that working men had a 60% greater chance of dying from heart disease or a stroke after they ditched their daily nap.
Most of us would find it a challenge to fit a snooze into our afternoons but even some workplaces are beginning to realise the benefits: read RSNG’s guide to napping for some pointers.
Getting 4.5 hours sleep means eating an extra 300 calories and putting on 10-15lbs a year
Short Sleep Makes You Fat Increasing your activity levels fast tracks you to a healthier, leaner body – most of the time. If it doesn’t the first thing to look at is your sleep. ‘Sleeping less than seven or eight hours a night will increase your probability of gaining weight,’ says Walker. In, fact a study by Dr Eve Van Cauter at University of Chicago found that people who slept 4.5 hours a night, rather than 8.5 hours, ate 300 calories more each day. Scale that up to a year, Walker says, and you’ll eat 70,000 extra cals, putting on 4.5-7kg (10-15lbs) of extra weight.
Another Van Cauter study showed that lean, healthy people on the 4-5 hours of sleep, which more than a third of us get, become ravenously hungry because inadequate sleep decreases levels of the fullness-signalling hormone leptin, while at the same time boosting levels of the hunger-driving hormone ghrelin. And it gets worse – Van Cauter also discovered that cravings for sweet, carb-rich foods and salty snacks increase 30-40% when we’re sleep deprived.
Bad Sleep Ages You By 15 Years If you think it’s macho and ‘alpha male’ to go without sleep, then you should hear the results of a University of Chicago experiment that took a group of lean, healthy young men in their mid-twenties and limited them to five hours of sleep per night. They measured their blood testosterone levels after one week and found that they had been blunted to the extent that they had been effectively ‘aged’ by 10-15 years in terms of testosterone virility.
Not only are you less likely to be able to procreate when sleep deprived, but you’re also going to be less attractive. Dr Tina Sundelin ran an experiment where two photos of the same person, one after five hours sleep, and the other after eight hours, were rated in a blind test. ‘The faces pictured after one night of short sleep were rated as looking more fatigued, less healthy, and significantly less attractive,’ says Walker.
We awake with a revised “Mind Wide Web” capable of divining solutions to impenetrable problems
Good Sleep Fuels Your Immune System One of the messiest sleep experiments Walker’s colleagues have done is when Dr Aric Prather at University of California squirted a dose of common cold virus up the noses of 150 healthy men and women. He then separated them according to how much sleep they had had in the week before and recorded which ones came down with a cold. The results were clear: the more sleep you had in the week before the less likely you were to get flu. On an average of five hours a night the infection rate was almost 50% – on seven hours a night it was just 18%.
REM Sleep Boosts Creativity In the fast-approaching world of automated work the only things that humans are going to be better at than machines are being creative, and making intuitive leaps of understanding. But to do this, says Walker, REM sleep is vital. ‘Apart from being a stoic sentinel that guards your sanity and emotional well-being, REM sleep and the act of dreaming have another distinct benefit: intelligent information processing that inspires creativity and promotes problem solving.’
This processing of vast banks of knowledge lights up the brain. ‘We awake with a revised “Mind Wide Web” that is capable of divining solutions to previously impenetrable problems.’ In fact, Humans are the only primates evolved to sleep on the ground, allowing for REM sleep, which temporarily paralyses our muscles from the chin down (apart from the heart and the diaphragm), so that we don’t ‘act out’ our dreams. Dreaming is one of the key reasons human intelligence developed in the first place...
WHAT NEXT? Find out your sleep score, and get some tips on how to improve it, with this online quiz.
Why We Sleep by Matthew Walker is available here
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