‘Sleep should be pre­scribed’

Neu­ro­sci­en­tist Matthew Walker has spent his life’s work re­search­ing how sleep loss in­creases our risk of cancer and Alzheimer’s. Rachel Cooke finds out what we can do about it

The Guardian Weekly - - Weekly Review - Why We Sleep is pub­lished by Allen Lane

Matthew Walker has learned to dread the ques­tion “What do you do?” At par­ties, it sig­nals the end of his evening; there­after, his new ac­quain­tance will in­evitably cling to him like ivy. On an aero­plane, it usu­ally means that while ev­ery­one else watches movies or reads a thriller, he will find him­self run­ning an hours-long salon for the ben­e­fit of pas­sen­gers and crew alike. “I’ve be­gun to lie,” he says. “Se­ri­ously. I just tell peo­ple I’m a dol­phin trainer. It’s bet­ter for ev­ery­one.”

Walker is a sleep sci­en­tist. To be spe­cific, he is the di­rec­tor of the Cen­ter for Hu­man Sleep Sci­ence at the Uni­ver­sity of Cal­i­for­nia, Berke­ley, a re­search in­sti­tute whose goal – pos­si­bly un­achiev­able – is to un­der­stand ev­ery­thing about sleep’s im­pact on us, from birth to death, in sick­ness and health. No won­der, then, that peo­ple long for his coun­sel. As the line be­tween work and leisure grows ever more blurred, rare is the per­son who doesn’t worry about their sleep. But even as we con­tem­plate the shad­ows be­neath our eyes, most of us don’t know the half of it – and per­haps this is the real rea­son Walker has stopped telling strangers how he makes his liv­ing. When Walker talks about sleep he can’t, in all con­science, limit him­self to whis­per­ing com­fort­ing noth­ings about camomile tea and warm baths. It’s his con­vic­tion that we are in the midst of a “cat­a­strophic sleep-loss epi­demic”, the con­se­quences of

‘We chas­tise peo­ple for sleep­ing what are only nor­mal amounts. We think of them as sloth­ful’

which are far graver than any of us could imag­ine. This sit­u­a­tion, he be­lieves, is only likely to change if gov­ern­ment gets in­volved.

Walker has spent the last four and a half years writ­ing Why We Sleep, a com­plex but ur­gent book that ex­am­ines the ef­fects of this epi­demic close up, the idea be­ing that once peo­ple know of the pow­er­ful links be­tween sleep loss and, among other things, Alzheimer’s dis­ease, cancer, di­a­betes, obe­sity and poor men­tal health, they will try harder to get the rec­om­mended eight hours a night (sleep de­pri­va­tion, amaz­ing as this may sound to Don­ald Trump types, con­sti­tutes any­thing less than seven hours). But, in the end, the in­di­vid­ual can achieve only so much. Walker wants ma­jor in­sti­tu­tions and law­mak­ers to take up his ideas, too. “No as­pect of our bi­ol­ogy is left un­scathed by sleep de­pri­va­tion,” he says. “It sinks down into ev­ery pos­si­ble nook and cranny. And yet no one is do­ing any­thing about it. Things have to change: in the work­place and our com­mu­ni­ties, our homes and fam­i­lies. But when did you ever see an NHS poster urg­ing sleep on peo­ple? When did a doc­tor pre­scribe, not sleep­ing pills, but sleep it­self? It needs to be pri­ori­tised, even in­cen­tivised. Sleep loss costs the UK econ­omy over £30bn [$40bn] a year in lost rev­enue, or 2% of GDP. I could dou­ble the NHS bud­get if only they would in­sti­tute poli­cies to man­date or pow­er­fully en­cour­age sleep.”

Why are we so sleep-de­prived? What has hap­pened? In 1942, less than 8% of the pop­u­la­tion was try­ing to sur­vive on six hours or less sleep a night; in 2017, al­most one in two peo­ple is. The rea­sons are seem­ingly ob­vi­ous. “First, we elec­tri­fied the night,” Walker says. “Light is a pro­found de­grader of our sleep. Sec­ond, there is the is­sue of work: not only the por­ous bor­ders be­tween when you start and fin­ish, but longer com­muter times, too. No one wants to give up time with their fam­ily or en­ter­tain­ment, so they give up sleep in­stead. And anx­i­ety plays a part. We’re a lone­lier, more de­pressed so­ci­ety. Al­co­hol and caf­feine are more widely avail­able. All th­ese are the en­e­mies of sleep.”

But Walker be­lieves, too, that in the de­vel­oped world sleep is strongly as­so­ci­ated with weak­ness, even shame. “We have stig­ma­tised sleep with the la­bel of lazi­ness. We want to seem busy, and one way we ex­press that is by pro­claim­ing how lit­tle sleep we’re get­ting. It’s a badge of hon­our. When I give lec­tures, peo­ple will wait be­hind un­til there is no one around and then tell me qui­etly: ‘I seem to be one of those peo­ple who need eight or nine hours’ sleep.’ It’s em­bar­rass­ing to say it in pub­lic. They would rather wait 45 min­utes for the con­fes­sional. They’re con­vinced that they’re ab­nor­mal, and why wouldn’t they be? We chas­tise peo­ple for sleep­ing what are, af­ter all, only suf­fi­cient amounts. We think of them as sloth­ful. No one would look at an in­fant baby asleep, and say ‘What a lazy baby!’ We know sleep­ing is non-ne­go­tiable for a baby. But that no­tion is quickly aban­doned [as we grow up]. Hu­mans are the only species that de­lib­er­ately de­prive them­selves of sleep for no ap­par­ent rea­son.” In case you’re won­der­ing, the num­ber of peo­ple who can sur­vive on five hours of sleep or less with­out any im­pair­ment, ex­pressed as a per­cent of the pop­u­la­tion and rounded to a whole num­ber, is zero.

The world of sleep sci­ence is still rel­a­tively small. But it is grow­ing ex­po­nen­tially, thanks both to de­mand and new tech­nol­ogy, which en­ables re­searchers to have what Walker de­scribes as “VIP ac­cess” to the sleep­ing brain. Walker, who is 44 and was born in Liver­pool, has been in the field for more than 20 years, hav­ing pub­lished his first re­search pa­per at the age of just 21. “I would love to tell you that I was fas­ci­nated by con­scious states from child­hood,” he says. “But in truth, it was ac­ci­den­tal.” He started out study­ing for a med­i­cal de­gree, but hav­ing dis­cov­ered that doc­tor­ing wasn’t for him he switched to neu­ro­science, and af­ter grad­u­a­tion, be­gan a PhD in neu­ro­phys­i­ol­ogy sup­ported by the UK’s Med­i­cal Re­search Coun­cil. It was while work­ing on this that he stum­bled into the realm of sleep.

“I was look­ing at the brain­wave pat­terns of peo­ple with dif­fer­ent forms of de­men­tia, but I was fail­ing mis­er­ably at find­ing any 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 brain that had to do with con­trolled sleep, while other types left those sleep cen­tres unaf­fected. I re­alised my mis­take. I had been mea­sur­ing the brain­wave ac­tiv­ity of my pa­tients while they were awake, when I should have been do­ing so 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 is 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 sim­ple ques­tion: ‘Why do we sleep?’ That seemed to me to be the great­est sci­en­tific mys­tery. I was go­ing to at­tack it, and I was go­ing to do that in two years. But I was naive. I didn’t re­alise that some of the great­est sci­en­tific minds had been try­ing to do the same thing for their en­tire 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 non-ne­go­tiable eight-hour sleep op­por­tu­nity ev­ery night, and I keep very reg­u­lar hours: if there is one thing I tell peo­ple, it’s to go to bed and to wake up at the same time ev­ery day, no mat­ter what. I take my sleep in­cred­i­bly se­ri­ously be­cause I have seen the ev­i­dence. Once you know that af­ter just one night of

only 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 fail to close, Walker ad­mits that he can be a touch “Woody Allen-neu­rotic”. When, for in­stance, he came to Lon­don ear­lier this year, he found him­self jet-lagged and wide awake at 2am. His prob­lem then, as al­ways in th­ese sit­u­a­tions, was that he knew too much. His brain be­gan 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 end, it seems, even world ex­perts in sleep act like the rest of us when struck by in­som­nia. He turned on a light and read for a while.

Will Why We Sleep have the im­pact its au­thor hopes? I’m not sure: the sci­ence bits, it must be said, re­quire some con­cen­tra­tion. 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 ear­lier – a regime to which I am stick­ing. In a way, I was pre­pared for this. I first en­coun­tered Walker some months ago, when he spoke at an event at Som­er­set House in Lon­don, and he struck me then as both pas­sion­ate and con­vinc­ing.

The ev­i­dence Walker presents, how­ever, is enough to send any­one early to bed. With­out sleep, there is low en­ergy and dis­ease. With sleep, there is vi­tal­ity and health. More than 20 large-scale epi­demi­o­log­i­cal stud­ies all re­port the same clear re­la­tion­ship: the shorter your sleep, the shorter your life. 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 a night (part of the rea­son for this has to do with blood pres­sure: even just one night of mod­est sleep re­duc­tion will speed the rate of a per­son’s heart and sig­nif­i­cantly in­crease their blood pres­sure).

A lack of sleep also ap­pears to hi­jack the body’s ef­fec­tive con­trol of blood sugar, the cells of the sleep-de­prived ap­pear­ing, in ex­per­i­ments, to be­come less re­spon­sive to in­sulin, and thus to cause a pre­di­a­betic state of hy­per­gly­caemia. When your sleep be­comes short, more­over, you are sus­cep­ti­ble to weight gain. Among the rea­sons for this are the fact that in­ad­e­quate sleep de­creases lev­els of the sati­ety-sig­nalling hor­mone, lep­tin, and in­creases lev­els of the hunger-sig­nalling hor­mone, ghre­lin. “I’m not go­ing to say that the obe­sity cri­sis is caused by the sleep-loss epi­demic alone,” he says. “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.” Tired­ness, of course, also af­fects mo­ti­va­tion.

Sleep has a pow­er­ful ef­fect on the im­mune sys­tem, which is why, when we have flu, our first in­stinct is to go to bed: our body is try­ing to sleep it­self well. Re­duce sleep even for a sin­gle night, and your re­silience is dras­ti­cally re­duced. If you are tired, you are more likely to catch a cold. The well-rested also re­spond bet­ter to the flu vac­cine. As Walker has al­ready said, more gravely, stud­ies show that short sleep can af­fect our cancer-fight­ing im­mune cells. A num­ber of epi­demi­o­log­i­cal stud­ies have re­ported that night-time shift work and the dis­rup­tion to cir­ca­dian sleep and rhythms that it causes in­crease the odds of de­vel­op­ing can­cers in­clud­ing breast, prostate, en­dometrium and colon.

Get­ting too lit­tle sleep across the adult life­span will sig­nif­i­cantly raise your risk of de­vel­op­ing Alzheimer’s dis­ease. The rea­sons for this are dif­fi­cult to sum­marise, but in essence it has to do with the amy­loid de­posits (a toxin pro­tein) that ac­cu­mu­late in the brains of those suf­fer­ing from the dis­ease, killing the sur­round­ing cells. Dur­ing deep sleep, such de­posits are ef­fec­tively cleaned from the brain. What oc­curs in an Alzheimer’s pa­tient is a kind of vi­cious cir­cle. More amy­loid, less deep sleep; less deep sleep, more amy­loid, and so on. (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 needed, both went on to de­velop the dis­ease; it is, more­over, a myth that older adults need less sleep.) Away from de­men­tia, sleep aids

‘No one wants to give up time with their fam­ily or en­ter­tain­ment, so they give up sleep in­stead’

our abil­ity to make new mem­o­ries, and re­stores our ca­pac­ity for learn­ing.

And then there is sleep’s ef­fect on men­tal health. When your mother told you that ev­ery­thing would look bet­ter in the morn­ing, she was wise. Walker’s book in­cludes a long sec­tion on dreams (which, says Walker, con­trary to Freud, can­not be an­a­lysed). Here he de­tails the var­i­ous ways in which the dream state con­nects to cre­ativ­ity. He also sug­gests that dream­ing is a sooth­ing balm. If we sleep to re­mem­ber, then we also sleep to for­get. Deep sleep – the part when we be­gin to dream – is a ther­a­peu­tic state dur­ing which we cast off the emo­tional charge of our ex­pe­ri­ences, mak­ing them eas­ier to bear. Sleep, or a lack of it, also af­fects our mood more gen­er­ally. Brain scans car­ried out by Walker re­vealed a 60% am­pli­fi­ca­tion in the re­ac­tiv­ity of the amyg­dala – a key spot for trig­ger­ing anger and rage – in those who were sleep-de­prived. In chil­dren, sleep­less­ness has been linked to ag­gres­sion and bul­ly­ing; in ado­les­cents, to sui­ci­dal thoughts. In­suf­fi­cient sleep is also as­so­ci­ated with re­lapse in ad­dic­tion disor­ders. A pre­vail­ing view in psy­chi­a­try is that men­tal disor­ders cause sleep dis­rup­tion. But Walker be­lieves it is, in fact, a two-way street. Reg­u­lated sleep can im­prove the health of, for in­stance, those with bipo­lar dis­or­der.

I’ve men­tioned deep sleep in this (too brief) sum­mary sev­eral times. What is it, ex­actly? We sleep in 90-minute cy­cles, and it’s only to­wards the end of each one of th­ese that we go into deep sleep. Each cy­cle com­prises two kinds 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 still have their mys­ter­ies, his voice changes. He sounds 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 mean that so-called power naps are worth­less? “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 too much 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.” How is it pos­si­ble to tell if a per­son is sleep-de­prived? Walker thinks we should trust our in­stincts. Those who would sleep on if their alarm clock was turned off are sim­ply not get­ting enough. Ditto those who need caf­feine in the af­ter­noon to stay awake. “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 in­di­vid­ual do? First, they should avoid pulling “all-nighters”, at their desks or on the dance­floor. Af­ter be­ing awake for 19 hours, you’re as cog­ni­tively im­paired as some­one who is drunk. Sec­ond, they should start think­ing about sleep as a kind of work, like go­ing to the gym (with the key dif­fer­ence that it is both free and, if you’re 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 start think­ing of mid­night more in terms of its orig­i­nal mean­ing: as the mid­dle of the night. Schools should con­sider later starts for stu­dents; such de­lays cor­re­late with im­proved IQs. Com­pa­nies should think about re­ward­ing sleep. Pro­duc­tiv­ity will rise, and mo­ti­va­tion, cre­ativ­ity and even lev­els of hon­esty will be im­proved. Sleep can be mea­sured us­ing track­ing de­vices, and some far­sighted com­pa­nies in the US al­ready give em­ploy­ees time off if they clock enough of it. Sleep­ing pills, by the way, are to 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 mo­biles and com­put­ers from the bed­room – and quite right, too, given the ef­fect of LED-emit­ting de­vices on mela­tonin, the sleep-in­duc­ing hor­mone. Ul­ti­mately, though, Walker be­lieves that tech­nol­ogy will 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 still most want to an­swer? For a while, he is 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.”

‘No as­pect of our bi­ol­ogy is left un­scathed by sleep de­pri­va­tion. It sinks into ev­ery nook and cranny’

Saroyan Humphrey; Deco/Alamy

‘Sleep will come to be seen as a pre­ven­ta­tive medicine’ … neu­ro­sci­en­tist Matthew Walker, and, top, brain waves dur­ing REM sleep

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