“I had been looking at the brainwave patterns of individuals with unique kinds of dementia, but I was failing miserably at finding some difference between them,” he recalls now. One night, however, he read a scientific paper that changed everything. It described which parts of the brain were being attacked by these different types of dementia: “Some were attacking parts of the mind that had to do with controlled sleep, while other kinds left those sleep centres unaffected. I realised my mistake. I was measuring the brainwave activity of my patients while they were awake, when I should have been doing this while they were asleep.” Over the next six months, Walker taught himself how to set up a sleep laboratory and, sure enough, the recordings he made in it subsequently spoke loudly of a clear difference between patients. Sleep, it seemed, could be a new early diagnostic litmus test for different subtypes of dementia.
After this, sleep became his obsession. “Only then did I ask: what’s this thing called sleep, and what does it do? I was always curious, annoyingly so, but when I started to read about sleep, I would look up and hours would have gone by. No one could answer the easy question? That seemed to be the scientific mystery. I went to attack it, and I went to do that in a couple of decades. But I was naive. I didn’t realise that some of the greatest scientific minds had been attempting to do the same thing for their careers. That was two decades ago, and I’m still cracking away.” After gaining his doctorate, he moved to the US. Formerly a professor of psychiatry at Harvard Medical School, he is now professor of neuroscience and psychology at the University of California.
Does his obsession extend to the bedroom? Does he take his own advice when it comes to sleep? “Yes. I give myself a sleep chance every night, and I keep hours: if there is one thing I tell people, it’s to go to bed and to wake up at precisely the same time every day, no matter what. I take my sleep incredibly because I have seen the evidence. As soon as you know that after just one night of just four or five hours’ sleep, your natural killer cells — the ones that attack the cancer cells that appear in your body every day — drop by 70%, or that a lack of sleep is linked to cancer of the bowel, prostate and breast, or even just that the World Health Organisation has classed any form of night-time shift work as a probable carcinogen, how could you do anything else?”
There is, however, a sting in the tale. Should his eyelids don’t close, Walker admits that he can be a touch “Woody Allen-neurotic”. When, for example, he came to London over the summer, he found himself jet-lagged and wide awake in his hotel room. His problem as always in these situations, was that he knew too much. His brain started to race. “I thought: my orexin isn’t being turned off, the sensory gate of my thalamus is wedged open, my dorsolateral prefrontal cortex won’t shut down, and my melatonin surge won’t happen for another seven hours.” What did he do? In the long run, it seems, even world experts in sleep behave like the rest of us when struck by the curse of sleeplessness. He read for some time and turned on a light.
Can Why We Sleep have the effect its author hopes? I’m not sure. But what I can tell you is that it had a powerful effect on me. After reading it, I was determined to go to bed a regime to which I am sticking. In a way, I was prepared for this. I first struck Walker several months ago, when he spoke at an event at Somerset House in London, and he struck me then as both passionate and convincing (our later interview occurs via Skype from the basement of his “sleep centre”, a spot which, with its bedrooms off a long corridor, apparently looks like the ward of a private hospital). But in a different way, it was unexpected. I am mostly immune to health advice. Inside my head, there is always a voice that says “just enjoy life while it lasts”.
The evidence Walker gifts, however, is enough to send anyone. It’s no kind of choice at all. Without sleep, there is energy and disease. With sleep, there is health and vitality. More than 20 large scale epidemiological studies the shorter your life, all report the relationship that is clear: the shorter your sleep. To take just one example, adults aged 45 years or older who sleep less than six hours a night are 200% more likely to have a heart attack or stroke in their lifetime, as compared with those sleeping seven or eight hours each night (part of the reason behind this has to do with blood pressure: even just one night of modest sleep loss will speed the rate of a person’s heart, hour upon hour, and significantly increase their blood pressure).
A lack of sleep appears to hijack the effective control of blood glucose, the cells of the appearing of the body, in experiments, to cause a prediabetic state of hyperglycaemia, and thus to become less responsive to insulin. When your sleep becomes short, moreover, you are vulnerable to weight gain. Are the fact that insufficient sleep reduces levels of leptin, this satiety-signalling hormone, and raises levels of this hunger-signalling hormone. “I’m not going to say that the obesity crisis is caused by the sleep-loss epidemic alone,” says Walker. “It’s not. However, processed food and sedentary lifestyles do not adequately explain its rise. Something is missing. It’s now clear that sleep is that third ingredient.” Motivation, also affects.
Sleep has a potent influence on the immune system, which is why, when we have flu, our first instinct is to go to bed: our body is attempting to sleep itself. Reduce sleep even for a night, and your endurance is reduced. You are more likely to catch a cold, if you are tired. The well-rested also respond better to the flu vaccine. As Walker has already said studies indicate that short sleep can affect our cancer-fighting immune cells. Numerous epidemiological studies have reported that the disruption and night-time shift work to circadian rhythms and rhythms that it causes increase the odds of cancers including colon, prostate, endometrium and breast.
Getting too little sleep will raise your risk of developing Alzheimer’s disease. The reasons for this are hard to summarise, but in essence it’s to do with the amyloid deposits (a poison protein) that accumulate in the brains of those suffering from the illness, killing the surrounding cells. In the brain deposits are effectively cleaned during deep sleep. What occurs in an Alzheimer’s patient is a kind of vicious circle. These plaques build up, especially in the brain’s deep-sleep-generating regions, degrading and attacking them. Our ability to remove them is therefore lessened by the loss of deep sleep brought on by this assault. More amyloid less deep sleep, on, and so more amyloid. (In his book, Walker notes “unscientifically” that he has always found it curious that Margaret Thatcher and Ronald Reagan, both of whom were vocal about how little sleep they had, both went on to develop the disease; it is, moreover, a myth that older adults need less sleep.) Away from dementia, sleep aids our ability and restores our capacity.
And then there is sleep’s impact on health. She had been wise when your mom told you that what would look in the morning. Walker’s book contains a long section on dreams (which, says Walker, contrary to Dr Freud, can’t be analysed). Here he details the many methods by which the dream state and creativity connect together. He also indicates that dreaming is a balm. If we sleep to recall (see above), then we also sleep to forget. Deep sleep — the part when we begin to dream — is a state during which we cast off the charge of our experiences, which makes them more easy to bear. Sleep, or a lack of itaffects our mood more generally. Brain scans carried out by Walker showed a 60% amplification in the reactivity of the amygdala — a spot for sparking anger and rage. In adolescents, sleeplessness was linked in children, to suicidal thoughts. Insufficient sleep is associated with relapse in addiction disorders. A prevailing view in psychiatry is that sleep disruption is caused by mental disorders. But Walker considers it is, in actuality, a two-way road. Regulated sleep can improve the health of, for example, people who have bipolar disorder.
I have mentioned profound sleep in this (too brief) summary several times. What is it, exactly? We sleep in cycles, and it’s only towards the end of every one of these that we go into deep sleep. Each cycle comprises two types of sleep. First, there is NREM sleep (non-rapid eye movement sleep); this is then followed by REM (rapid eye movement) sleep. When Walker talks about these cycles, which have their mysteries, his voice changes. He seems bewitched, almost dazed.
“During NREM sleep, your brain goes into this incredible synchronised pattern of rhythmic chanting,” he says. “There’s a remarkable unity across the surface of the brain, like a deep, slow mantra. Researchers were once fooled that this state was similar to a coma. But nothing could be further from the truth. Vast amounts of memory processing is going on. To produce these brainwaves, hundreds of thousands of cells all sing together, and then go silent, and on and on. Meanwhile, your body settles into this lovely low state of energy, the best blood-pressure medicine you could ever hope for. REM sleep, on the other hand, is sometimes known as paradoxical sleep, because the brain patterns are identical to when you’re awake. It’s an incredibly active brain state. Your heart and nervous system go through spurts of activity: we’re still not exactly sure why.”
Does the 90-minute cycle imply that so-called power naps are unworthy? “They can take the edge off basic sleepiness. But you need 90 minutes to get to deep sleep, and one cycle isn’t enough to do all the work. You need four or five cycles to get all the benefit.” Is it possible to have a lot of sleep? This is unclear. “There is no good evidence at the moment. But I do think 14 hours is too much. Too much water can kill you, and too much food, and I think ultimately the same will prove to be true for sleep.” Is it possible to tell if there is a person sleep-deprived? Walker thinks we should trust our instincts. Those who would sleep on if their alarm clock was turned off are not really getting enough. Ditto those who need caffeine in the afternoon. “I see it all the time,” he says. “I get on a flight at 10am when people should be at peak alert, and I look around, and half of the plane has immediately fallen asleep.”
So what can the person do? First, they should avoid pulling “all-nighters”, at their desks or on the dancefloor. You’re as impaired after being awake for 19 hours. Second, they should begin considering sleep as a kind of work, like going to the gym (with the crucial difference that it is both free and, if you are me, enjoyable). “People use alarms to wake up,” Walker says. “So why don’t we have a bedtime alarm to tell us we’ve got half an hour, that we should start cycling down?” We should begin thinking of midnight more in terms of its original meaning. Later begins should be considered by schools for students; such delays correlate with improved IQs. Companies should think about sleep. Productivity will rise, and motivation, creativity and even amounts of honesty will be improved. Sleep can be measured using tracking devices, and some businesses in the US already give employees time off if they clock enough of it. Pills, incidentally, should be avoided. Among other things, they can have a deleterious effect on memory.
Those who are focused on so-called “clean” sleep are determined to outlaw phones and computers in the bedroom — and quite right, too, given the impact of LED-emitting apparatus on melatonin, the sleep-inducing hormone. Ultimately, however, Walker believes that technology is going to be sleep’s saviour. “There is going to be a revolution in the quantified self in industrial nations,” he says. “We will know everything about our bodies from one day to the next in high fidelity. That will be a seismic shift, and we will then start to develop methods by which we can amplify different components of human sleep, and do that from the bedside. Sleep will come to be seen as a preventive medicine.”
What questions does Walker most want to answer? For a while, he’s quiet. “It’s so difficult,” he says, with a sigh. “There are so many. I would still like to know where we go, psychologically and physiologically, when we dream. Dreaming is the second state of human consciousness, and we have only scratched the surface so far. But I would also like to find out when sleep emerged. I like to posit a ridiculous theory, which is: perhaps sleep did not evolve. Perhaps it was the thing from which wakefulness emerged.” He laughs. “If I could have some kind of medical Tardis and go back in time to look at that, well, I would sleep better at night.”
Why We Sleep: The New Science of Sleep and Dreamsby Matthew Walker is published by Allen Lane (#20). To order a copy for #17 go toguardianbookshop.com or call 03303336846. Free UK p&p over #10 . Phone orders p, min p & of #1.99
Sleep in numbers
Two-thirds of adults in developed countries fail to get the nightly eight hours of sleep advocated by the World Health Organisation.
An adult sleeping just 6.75 hours a night would be predicted to live only to their early 60s without medical intervention.
A 2013 study reported that men who slept too small had a sperm count 29 percent lower than those who regularly get a full and restful night’s sleep.
If you drive a car when you’ve had less than five hours’ sleep, then you are 4.3 times more likely to be involved in a crash. If you push having had four hours, then you are 11.5 times more likely to be involved in an accident.
A hot bath aids sleep not because it makes you warm, but as your dilated blood vessels radiate inner heat, and your core body temperature drops. Your core temperature should drop about 1C to successfully initiate sleep.
The time required to reach physical fatigue by athletes who obtain anything less than eight hours of sleep, and especially less than six hours, drops by 10-30%.
There are now more than 100 diagnosed sleep disorders, of which insomnia is the mostcommon.
Morning kinds, who prefer to awake at or about dawn, make up about 40 percent of the population. Types, who prefer to go to bed and wake up late, account for about 30%. The remaining 30% lie somewhere in between.