Sleepyheads

By Sora Song

We all know the risks of getting too little sleep, but is there danger in getting too much? A study in the journal Sleep suggests there may be. Researchers in Japan studied more than 104,000 people, ages 40 to 79, for nearly 10 years and found that those who reported sleeping eight or more hours a night were at higher risk of death than those who slept seven hours. Less was more: five or six hours of nightly shut-eye didn't increase mortality risk (but risk did rise in people getting less than 4.5 hours). Overall, subjects who slept seven hours had the best survival rate. --S.S.