Do You Really Need Seven Hours of Sleep?

By Temma Ehrenfeld | Newsweek Web Exclusive http://www.newsweek.com/id/113270?g=1

Yep, you do. Although people do vary in how much sleep they need, the differences are slight, and the vast majority of us (including seniors) need seven to eight hours. Most people who regularly get less than seven hours of rest are simply unaware of the damage that fatigue and sleepiness is doing to their bodies. Chronic "short-sleepers," as scientists call them, have forgotten what it feels like to be well-rested, says Robert Rosenberg, medical director of the Sleep Disorders Center of Prescott Valley, in Arizona.

The evidence indicates that a person who regularly sleeps less than seven hours a night functions as badly as someone who hasn't slept for one to three days, according to a research review published in the Journal of Clinical Sleep Medicine last year. Furthermore, the largest current longitudinal studies (one involving 21,268 people and another 10,308) showed that sleep-deprivation increased mortality: the chance of dying younger than people of the same age, gender and health-risk factors. In the larger study researchers at the Finnish Institute of Occupational Health assessed the sleep habits of the group in 1975 and 1981 and then checked to see who was still alive on Dec. 31, 2003. After comparing subjects' survival rates to the average for people of the same age (and adjusting for other known death risks, like smoking), the researchers concluded that lack of sleep increased mortality in the study participants by 26 percent for men and 21 percent for women. The cause of death might be accidents, or diseases exacerbated by sleep-deprivation. Other current research indicates that lack of sleep affects the body's hormones, immune system and metabolism; hence, it can be a risk factor for obesity, diabetes and heart disease.

To evaluate the quality of your own sleep—and whether you're getting enough—try these tools offered by the American Academy of Sleep Medicine