Q & A Library

Lack of sleep does appear to be associated with obesity - one theory is that sleep deprivation disrupts production of hormones that regulate appetite. But findings from a door-to-door government survey of 87,000 U.S. adults from 2004 through 2006 suggests that those who get the least sleep are also more likely to put their health at risk by smoking cigarettes, drinking too much alcohol, and not being physically active. In the case of cigarettes and physical inactivity, this was also true for those who slept nine or more hours per night.

The study was conducted by the National Center for Health Statistics, an arm of the Centers for Disease Control and Prevention. It doesn't prove that sleep deprivation leads to smoking or alcohol consumption - or vice versa - and it doesn't tell us what other factors might influence these risky health habits. In some cases, depression or stress could be the underlying reasons for not getting enough sleep and for drinking.

But the findings are striking. Here's a summary:

• Smoking: Of those who slept seven to eight hours a night only 18 percent were smokers compared to 31 percent of those who slept less than six hours and 26 percent of those who slept more than nine hours.
• Alcohol: Adults who got the least sleep were slightly more likely to have had five or more drinks in one day than those who got seven to eight hours, but here, the difference was only three percent: 19 percent of those who had a good night's sleep had five or more drinks a day compared to 22 percent of those who slept six hours or less.
• Physical Inactivity: For both men and women regardless of age, those who slept less than six or more than nine hours a night were more likely to be physically inactive than those who slept seven to eight.
• Obesity: The rate of obesity was highest (33 percent) among those who slept less than six hours and lowest (22 percent) among those who slept seven to eight hours a night. This held true for both men and women regardless of age.

Adequate sleep is key to a healthy lifestyle, and accumulating research suggests that it plays an even larger role in health than we once thought. There is more to learn about this subject. I'll keep you posted on developments. Meanwhile, if you're not getting seven to eight hours sleep per night, based on what we now know, it might benefit your weight - and your overall health - to strive for more shut-eye.

Andrew Weil, M.D.