How Much Is Enough Sleep?

There's no prescription for the perfect amount of sleep. Contrary to the long-held notion that every adult needs 8 hours of sleep a night, a new Washington State University study suggests that genetics may determine the amount of sleep an individual needs. That may explain the perky person you know who seems to thrive on less; she just may have inherited efficient sleep genes. On the other hand, people who seem to require an extreme amount of sleep may not be genetically programmed for it. Instead, they may suffer from a disorder such as obstructive sleep apnea, which interrupts shut-eye but can improve with treatment.