Study Ties 6-7 Hours of Sleep to Longer Life

February 15, 2002; Chicago, IL (AP) - Research suggests that adults live longer if they get six or seven hours of sleep a night rather than the accepted standard of eight hours. The research is based on a nationwide survey of 1.1 million adults. It found that those who slept eight hours a night were 12 percent more likely to die within six years than those who got 6.5 to 7.5 hours of sleep. The increased risk was more than 15 percent for those who reported getting more than 8.5 hours or less than about 4 hours nightly. The participants were ages 30 to 102. Few reported frequent insomnia, which was not associated with an increased risk of death.

Additional studies are needed to determine if setting your alarm clock earlier will actually improve your health," said the lead author, Dr. Daniel Kripke, a Psychiatrist at the University of California at San Diego. The study was published in the February issue of the Archives of General Psychiatry.

Sleep experts said the research had several flaws. The study was not designed to look at sleep's effect on longevity. It relied on patients' recollections of their sleep habits and did not ask if they took naps. It did not look at the quality of people's sleep or whether they felt drowsy all day. Dr. Phyllis Zee, Director of Northwestern Memorial Hospital's Sleep Disorders Center, said "participants who got little sleep or slept eight hours or more may have had medical problems that would explain their increased death rate."