Staying Sharp: Sleeping Your Way to the Top

Americans are not renowned for their powers of self-deprivation; doing without is not something we do particularly well. But experts say there is one necessity of life most of us consistently fail to get: a good night's sleep.

The recommended daily requirements should sound familiar: eight hours of sleep a night for adults and at least an hour more for adolescents. Yet 71% of American adults and 85% of teens do not get the suggested amount, to the detriment of body and mind. "Sleep is sort of like food," says Robert Stickgold, a cognitive neuroscientist at Harvard Medical School. But, he adds, there's one important difference: "You can be quite starved and still alive, and I think we appreciate how horrible that must be. But many of us live on the edge of sleep starvation and just accept it."

Part of the problem is we are so used to being chronically sleep deprived--and have become so adept at coping with that condition--that we no longer notice how exhausted we really are. In 2003, sleep expert David Dinges and colleagues at the University of Pennsylvania School of Medicine tested the effects of restricting slumber to eight, six or four hours a night for two weeks. During the first few days, subjects sleeping less than eight hours admitted to being fatigued and lacking alertness. But by Day 4, most people had adapted to their new baseline drowsiness and reported feeling fine--even as their cognitive performance continued to plummet.

Over time, the experiment's sleep-restricted subjects became so impaired that they had difficulty concentrating on even the simplest tasks, like pushing a button in response to a light. "The human brain is only capable of about 16 hours of wakefulness [a day]," says Dinges. "When you get beyond that, it can't function as efficiently, as accurately or as well."

In the real world, people overcome their somnolence--at least temporarily--by drinking coffee, taking a walk around the block or chatting with office mates. But then they find themselves nodding off in meetings or, worse, behind the wheel. Those short snatches of unconsciousness are what researchers call microsleep, a sure sign of sleep deprivation. "If people are falling asleep because 'the room was hot' or 'the meeting was boring,' that's not coping with sleep loss. I would argue that they're eroding their productive capability," says Dinges.

What most people don't realize is that the purpose of sleep may be more to rest the mind than to rest the body. Indeed, most of the benefits of eight hours' sleep seem to accrue to the brain: sleep helps consolidate memory, improve judgment, promote learning and concentration, boost mood, speed reaction time and sharpen problem solving and accuracy. According to Sonia Ancoli-Israel, a psychologist at the University of California at San Diego who has done extensive studies in the aging population, lack of sleep may even mimic the symptoms of dementia. In recent preliminary findings, she was able to improve cognitive function in patients with mild to moderate Alzheimer's simply by treating their underlying sleep disorder. "The need for sleep does not change a lot with age," says Ancoli-Israel, but often because of disruptive illnesses and the medications used to treat them, "the ability to sleep does."