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Sleep Loss Feeds Appetite
Dec. 6, 2004 - America's hectic lifestyle, fueled by sleep loss, is feeding the obesity epidemic, according to new research.
This week, two studies address this phenomenon -- building on earlier research pointing to the same conclusion - that sleep loss "brings about physiologic changes in the hormonal signals that promote hunger and, perhaps thereby, obesity," writes Jeffrey S. Flier, MD, with Beth Israel Deaconess Medical Center in Boston, in his editorial in Annals in Internal Medicine.
The "simple goals" to get a better night's sleep and more exercise "may well become a part of our future approach to combating obesity," writes Flier.
But sleep loss is just one factor in weight control, senior researcher Emmanuel Mignot, with the Howard Hughes Medical Institute at Stanford University, tells WebMD.
"It's certainly not the only factor. It's not that sleeping two or three more hours will solve a weight problem. It's one of many factors, and a factor that no one has looked at very much. It's good that sleep loss is getting so much attention right now. It's amazing what we're discovering." Mignot co-authored a study appearing in the journal Public Library of Science.
The Evidence Against Sleep Loss
Just last month, another study came to similar conclusions -- that chronic sleep loss triggers hormones that can lower the "appetite control" hormone leptin. Lower levels of leptin are associated with obesity. It's what researchers call the "yin yang" of appetite control. The hormone ghrelin is produced in the stomach and triggers hunger. Leptin is produced by fat cells and signals satiety, telling the brain when we have eaten enough.
Mignot's study investigated the effects of sleep loss on body mass index (BMI), an indirect measure of body fat. His was part of an ongoing sleep disorder study involving 1,024 Wisconsin state employees, all between 30 and 60 years old.
For researchers, this type of large-scale, ongoing study "is a good way to show that what you are finding applies to the general population," Mignot tells WebMD.
Every four years, each volunteer came to a sleep laboratory for an overnight stay, with blood sampling and a check of BMI and weight. Every five years, each completed a questionnaire about sleep habits; they also kept a six-day "sleep diary."
During the 15-year study period (since 1989) researchers found that short sleep was associated with low leptin levels. They show a 15% increase in ghrelin and a 16% decrease in leptin in people who consistently got only five hours of sleep.
"It shows that there is a regulatory problem," Mignot tells WebMD. "In natural evolution, when you were more active, you needed to eat more calories, so you had this natural reaction that increased your appetite and your sleep." Compare that with today, when people aren't as physically active yet burning the candle at both ends, either in traffic or in front of the TV. Also, food is more readily available. All those factors have caused increase in weight.
Researchers also show an association between sleep duration and BMI. Those getting three hours of sleep had a 5% increase in body weight. "That's not an enormous amount, but the effect might be underestimated," says Mignot. "Still, it's something we can do something about. It may be the reason why dieting has been so disappointing for so many people."
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