Get some sleep. That’s the urgent advice the newly refreshed science of slumber has for North Americans.
Never mind the majority who got less than the recommended eight hours of sleep last night. In April, yet another air-traffic controller – the fifth in as many months – was suspended for falling asleep on the job, leaving a plane circling Reno, Nev., for 16 minutes with no one in the control tower to talk to.
A more alert tin-pusher on duty in neighbouring California eventually talked down the pilot – who, unlike several infamous colleagues last year, was awake. A British pilots-union survey recently discovered that 20 per cent of pilots pass out on the job.
We live under the enduring spell of The Warrior Who Does Not Sleep, believing that many accomplished people survive on no more than 4.5 hours of “core sleep” a night. It’s a myth.
Many heroic non-sleepers used pills (John F. Kennedy was a walking pharmacy and once fell asleep interviewing a prospective secretary of agriculture) or were inveterate nappers (Napoleon, Ronald Reagan, Bill Clinton and even Winston Churchill, who used sleeping tablets and survived his famous midnight meetings by climbing into bed for an hour every single afternoon).
And as David Dinges, chief of the division of sleep and chronobiology at the University of Pennsylvania School of Medicine, points out: “There are lots of other heroic, high-achieving figures – Einstein, Albert Schweitzer – who got their sleep.”
But we want to believe we’re big kids who don’t need to go to bed.
Our stubborn refusal is making the world a measurably more dangerous place. Sleep scientists make few exceptions – most of us need 7½ hours in bed, and preferably eight, to be fully capable. Top performers (such as violinists) often need more than eight, plus an afternoon nap.
Human sleep is regulated by a circadian clock located in a tiny, cone-shaped but essential intersection of cells in the hypothalamus called the suprachiasmatic nucleus. It is in turn fed by ganglion cells in the retina, which take their cues from light and dark cycles – that is, the rising and setting sun, the main determinant of when we want to wake up and when we want to sleep.
The farther we stray from that simple schedule, the more we pay.
In a 2007 study, U.S. Army researchers found that two sleepless nights impaired the prefrontal cortex’s ability to integrate cognitive and emotional processes, which in turn interfered with the ability to make moral judgments. Sleeplessness, in other words, makes the mind one-dimensional, which is why it was used at Abu Ghraib. Sleep deprivation as a torture dates at least as far back as medieval Italy, when Ippolito Marsili invented the so-called alarm clock: The victim could avoid anal penetration if he stayed awake. (If you work in a modern corporation, this may sound familiar.) We need one hour of sleep for every two we stay alert.
Because sleep is when the body and especially the brain regenerate and repair themselves, sleeplessness has been identified as a factor in an endless list of afflictions, including hypertension, heart disease, diabetes, obesity, memory loss, bipolar disorder, reduced immunity, mood swings, impaired carbohydrate metabolism and increased heart-rate variability. Not to mention depression and substance abuse and the impairment of memory, self-expression and the ability to read emotions in others. Oh, and a hundred thousand motor-vehicle accidents a year
A hamster kept awake for three days will die. Randy Gardner, a high-school student, stayed awake for a record of just over 11 days as part of a 1964 Stanford University study. By the end, he couldn’t talk. Former prime minister Kim Campbell blamed the implosion of the Conservative Party under her leadership on sleep deprivation. Yasser Arafat slept only three to five hours a day – yet another model human being. We stay awake at our peril.
Going, going, yawn
But we stay awake nonetheless. The once-drowsy world of sleep research is currently engaged in a raging debate about whether we sleep more or less than we used to, historically. Diane Lauderdale, a sleep researcher at the University of Chicago, studied the sleep patterns of early-middle-aged adults, and found that average sleep duration ranged from 6.7 hours for white women to 5.1 hours for African-American men – well below the big eight.
Most people overestimate the amount they have slept: Pennsylvania’s Dr. Dinges estimates that 7½ to eight hours in bed snuggles down to 6.3 hours of actual shut-eye.
Even the “circadian larks” – the 20 per cent of the population who are early risers and can resist the effects of sleeplessness better than others – “eventually have problems,” he says.
It is Dr. Dinges and a group of colleagues who demonstrated over the past decade just how impairing sleep loss can be. In one of the most extensive sleep studies ever undertaken, the researchers restricted the sleep of their subjects continuously for two weeks, while administering psychomotor vigilance tests every day. The PVT requires a subject to press a button every time a signal appears on a screen. It’s not a hard test.
The findings were terrifying. The performances of people who got four to six hours of sleep a night declined steadily with every passing day. By the sixth day, a quarter of the six-hours group was falling asleep at the computer, lapsing into five times as many “microsleeps” as they had on Day 1. Working memory, accuracy and speed collapsed.
By the end of the two-week period, the six-hour-a-nighters were as impaired as they would have been staying up 24 hours straight – the equivalent, in performance terms, of being legally drunk.
This is not a trivial result: A two-second delay in response is enough to veer into oncoming traffic. Imagine the effects of six hours of sleep a night for four nights in a row combined with talking on a cellphone while driving (which, of course, no one does any more).
But six hours isn’t much sleep. Another researcher, Gregory Belenky, a psychiatrist who now heads the Sleep and Performance Research Centre at Washington State University in Spokane, performed much the same experiment on subjects who got seven hours sleep a night – more than the average North American. The seven-hour crowd’s scores slowed for three days, then plateaued at a lower rate of performance.
They insisted they were not impaired in any way, despite their drooping PVT scores. The first thing sleep deprivation knocks out, in other words, is your ability to tell if you’re sleep-deprived.
And forget about paying off your sleep debt. “It’ll take several weeks to get performance back,” Dr. Belenky says. “And it isn’t enough to sleep in on the weekends.”
Rattled on the ‘rattler’ shift
A deeper cause of sleeplessness – and a more serious safety issue – is the growing popularity of night shifts, early starts and extended hours. All three are popular cost-saving devices in a recession-conscious, union-wary economy.
Night shifts are particularly nasty because they shorten the light-dark cycle of our circadian clocks – the same effect as the jet lag produced by flying west to east. Most shift workers get off at 6 a.m., drive home to a rising run, fall asleep at 8 a.m., but then wake up at 1 p.m., as their circadian body temperature rises. As a result, Dr. Belenky estimates, the average shift worker gets five hours sleep a night – “which is not enough.”
Which workers are most affected by 24-hour shift work? Precisely the ones you want at their sharpest – train and truck drivers, pilots, police officers, nurses and physicians, financial traders and power-plant and utility workers.
If the night shifts are staggered, they’re even more pernicious. The “rattler” shift brings an air-traffic controller in from 4 a.m. to midnight on Monday, and then earlier and earlier each day until Thursday, when he finishes his shift at 2 p.m. and comes back in to do an all-night shift at midnight. Air-traffic controllers average just over two hours of sleep before such a midnight shift.
In other words, you might not want to arrive on a red-eye flight before 8 on a Friday morning – “not if it takes more than 10 minutes from top of descent to landing,” Dr. Belenky says. One solution that has been successful in Europe is controlled on-the-job naps.
When the latter idea was introduced in the United States, government-spending hawks laughed the idea out of Congress. Better, apparently, to die in a plane crash.
On the red-eye
If we aren’t sleeping, what are we doing? Mathias Basner, a medical researcher at the University of Pennsylvania School of Medicine, conducted a time-use survey of nearly 50,000 people. He found that the biggest sleep bandits in North America are work, travel (including commuting and grocery shopping) and social and leisure activities such as family time.
The study didn’t look at the time-eating capacity of online activity, but “it’s a reasonable hypothesis,” Dr. Dinges says.
The biggest sleep losers are men between the ages of 45 and 54. Remember that, darling, the next time you wake me up at 3 a.m. for snoring.
But “the real issue” as to why we are so sleep-challenged today, Dr. Dinges argues, “is the value of time. Because it’s under our discretionary control, time becomes a commodity, and it becomes a great deal more valuable. For many people these days, time is worth more than money. Anything that keeps time trapped in, that eludes our discretionary ability to control time, is seen as something that’s expendable.”
Thus to maximize our time-use profits, we sleep less and work and shop and Facebook more. “Social factors now control time, asleep and awake,” Dr. Dinges says, “even though sunset and sunrise were what we evolved by.”
The true north, sleepy and free
There was a lot of yammer about national economic productivity during the recent election campaign, but in terms of addressing our fundamental capacity to be productive by getting enough sleep, Canada is still snoozing.
Sleep medicine is a board-certified medical subspecialty in the U.S., but not so here, where the Calgary police force and hospital nurses are among the few professional groups to have openly addressed the exhaustion issue. The rest of us have just grown used to being a sleepy society.
“Sleep is the No. 1 performance enhancer for meeting the challenge of the next day,” Dr. Dinges says. “We need to reprioritize sleep – make it more important than TV, more important than long commutes, more important than a lot of irrelevant social-networking activities that make us feel good. Ten minutes a day on e-mail may be enough.” Radical!
His cause may be helped by sleep’s emergence as one of the new darlings of scientific research. The slowly dawning recognition that sleep is essential to both self-reliance and public performance, no matter what the boss says, has “made sleep medicine kind of a fair-haired child, scientifically,” Dr. Dinges declares.
“But it’s also up against this huge social desire to be awake. Basically we’ve become addicted to a 24-hour cycle that challenges our biology.”
More sleep? Perchance we dream.
Ian Brown is a feature writer for The Globe and Mail.