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Sleep off the fat

Posted: May 28, 2009

Research supports the connection between the amount of sleep you get and the levels of appetite-regulating hormones in your body, and points to an association between sleep deprivation and higher body mass index.

Dr. Shahrad Teheri, an endocrinologist at Bristol University is the lead author of several studies including one using data from the Wisconsin Sleep Cohort*, which tracked the sleep habits of over 1,000 volunteers for 17 years. They found that those people who slept on average for five hours or less compared to those who slept around eight hours each night had a higher body mass index. Blood samples from the volunteers revealed that the sleep-deprived had higher levels of ghrelin in their blood. Ghrelin, a hormone produced in the stomach, sends out hunger signals to the brain.

The same group of volunteers who tested positive for higher levels of hunger-stimulating ghrelin also had lower levels of leptin. Leptin,a hormone that also regulates appetite, is produced by fat cells and signals to your brain that you've had enough to eat. The end result? Too little sleep produces a hormonal imbalance of high ghrelin/low leptin that stimulates a craving for food, which in turn leads to the consumption of extra calories.

"Before this, people thought obesity was the result of sitting on your butt and stuffing your face," Teheri said. "But it turns out sleep has an influence. It makes sense to me personally, because when I was a sleep-deprived medical resident, I always had the munchies."

According to Terry Young, PhD, a professor of epidemiology at the University of Wisconsin-Madison, associate editor for the journal SLEEP, and co-author of Teheri's study, "While there is a lot of attention on diet and exercise for weight loss, these studies underscore the importance of adequate sleep. Unfortunately, people think of sleep as an irresponsible activity. It's as if they are being macho, and want to prove how busy and important their lives are. I predict someday that attitude will be as socially unacceptable as smoking."

*In 1988, Dr. Terry Young, PhD initiated the landmark Wisconsin Sleep Cohort Study, a longitudinal, population-based study of 1,500 adults that continues today.

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