By Tina Hesman Saey, Science News
For many people, days just don’t seem long enough. In order to cram everything into one 24-hour period, something has to give. Judging by many surveys of Americans, it’s sleep.
Sleep is regarded by some as unproductive, wasteful downtime. People who would rather hit the hay than the dance floor are told that only losers snooze and that they can sleep when they’re dead.
But new data about sleep’s benefits suggest that losing sleep might speed up death’s arrival. Recent research also shows that people who don’t snooze enough face a higher risk of losing their health than those who regularly get a good night’s sleep.
“What is certain is that we can’t do without sleep,” says Peter Meerlo, a neuroscientist at the University of Groningen in the Netherlands.
Some of the consequences of lost sleep are immediate, obvious and unpleasant, such as a toddler’s crabbiness after missing a nap. Older children and adults get irritable when tired, too. Sleepy students don’t learn or perform as well as their well-rested peers. And nodding off at work probably won’t help anyone get a promotion.
Other penalties for staying up too late can be far more serious, even deadly. Studies have linked chronic sleep loss to obesity, heart disease, high blood pressure, diabetes and shorter lives (SN: 2/8/03, p. 85) in people and laboratory animals. And now, a new study links sleep loss in mice to Alzheimer’s disease plaques (SN: 10/24/09, p. 11). And some evidence suggests that stinting on sleep night after night may cause long-term — maybe even permanent — changes in the brain, some of which may predispose people to mental disorders such as depression.
Just one night of short sleep has been shown to increase levels of inflammatory chemicals in the blood (SN: 10/11/08,p. 14) and increase hunger-promoting hormones. A week of getting just two hours less sleep per night than usual changed the way people in one study responded to glucose, mirroring a change seen in people who develop diabetes.
And lack of sleep can also have immediate injurious or fatal consequences: The National Highway Transportation Safety Administration estimates that drowsy-driving crashes result in about 40,000 nonfatal injuries and 1,550 deaths each year, probably a conservative estimate. Now, scientists are trying to understand not only how sleep deprivation affects driving performance, but also why one sleepy person might drive fine while another becomes a road menace.
Too tired to function
Nodding off behind the wheel is a common occurrence in David Dinges’ lab at the University of Pennsylvania School of Medicine in Philadelphia.
Dinges and his colleagues limit volunteers’ time in bed to four hours a night for five nights, then let the volunteers sleep up to 10 hours for two days. The aim of the experiments is to learn more about how the brain responds to the kind of chronic sleep deprivation people experience in real life, and to find out how much sleep is needed to repay the debt.