Sleep less for better health

USA Today

The truism that all adults need at least eight hours of sleep a night for good health should be put to rest by mounting evidence that less may be better.

People who sleep about seven hours a night live the longest, three huge studies have found, the newest out in the February issue of the journal SLEEP. Still, many sleep experts think lots of adults get too little rest, and that can lead to dangerous health problems.

The latest report from Japanese researchers found that adults getting an average of seven hours had the lowest death rates. Surprisingly, less sleep, even as little as four hours a night, didn’t significantly increase deaths for men and only lowered survival for women if they averaged less than four hours. But adults, who slept longer than seven hours, particularly women, were likely to die during the 10 years.

Other studies came to similar conclusions, says psychiatrist Daniel Kripke, a sleep researcher at University of California-San Diego School of Medicine. Doctors shouldn’t tell all patients to get at least eight hours of sleep, he says. Hormonal changes triggered by darkness or other unknown biological effects from long sleep could be affecting survival, Kripke says.

But short sleepers may suffer other bad effects. In his brief studies, those sleeping four to five and a half hours did poorly on tests that measure memory, clear thinking and ability to pay attention, “and they did progressively worse as the week went on,” says psychologist David Dinges of University of Pennsylvania School of Medicine. Adults who slept about seven hours performed best, he says.

Other smaller studies have found adults who sleep less than six hours a night may be at higher risk for diabetes and obesity. And sleep deprivation also causes car crashes.

“People should get as many hours sleep as they need to feel rested,” says Kripke.