(RxWiki News) That midnight snack you're stealing while you're struggling to get back to sleep may satisfy late night hunger - but it may also be extra calories your body doesn't need.
A recent study found, like related studies before it, that not getting enough sleep can mess with the hormones that control hunger and appetite, thereby leading people to consume more calories than they need and potentially increasing their likelihood of becoming obese.
"Get plenty of sleep each night to help control your weight."
Dr. Virend Somers, M.D., Ph.D., professor of medicine and cardiovascular disease at the Mayo Clinic, and his colleagues investigated the connection between the hormones that stimulate hunger and insufficient sleep.
The two primary hormones involved in appetite control are leptin and ghrelin. Leptin is released in response to excessive eating to inhibit the appetite, and gherkin stimulates the appetite in the gastrointestinal tract.
For the study, 17 normal, healthy young mean and women spent eight days in the sleep study: half slept normally and half only got two thirds of their normal sleep. Both groups could eat as much as they wanted during the study.
They found that the sleep-deprived group not only consumed more calories, but they didn't expend enough excess energy over the other group to burn off those extra calories.
The group that slept one hour and 20 minutes less than the control group ate an average of an extra 549 calories - about the number of calories in McDonald's Big Mac or two slices of a Pizza Hut 12-inch pepperoni pizza.
The energy expenditure of the people in both groups remained about the same, so those who got less sleep probably did not burn off the extra 550 calories, said the authors.
The researchers also found an association between lack of sleep and higher levels of leptin and lower levels of ghrelin, but they believe these changes in leptin and ghrelin most likely resulted from over-eating rather than actually causing the over-eating.
Previous studies have shown that lack of sleep alone can decrease leptin and increase ghrelin - thereby making insomniacs hungrier and less likely to feel satisfied after eating.
According to Dr. William Kohler, director of the Florida Sleep Institute in Spring Hill, FL, another possible explanation for this study showing an opposite effect from sleep deprivation on leptin and ghrelin might be a condition called leptin-resistance.
Regardless of the mechanism, however, Kohler said this study continues to add to the body of research that shows a link exists between poor sleep and obesity.
"The literature is mixed as to the exact effect on leptin and ghrelin," Kohler said. "But this is an important study in correlating lack of sleep to obesity and increased caloric consumption. Previous work has shown a definite correlation between sleep deprivation and obesity."
This study was a small one, the authors noted, so more research on sleep deprivation and obesity would be worthwhile. But with high numbers of people who suffer from sleeping issues, understanding the precise mechanisms of the link could be helpful.
"Sleep deprivation is a growing problem, with 28 percent of adults now reporting that they get six or fewer hours of sleep per night," said co-author Andrew D. Calvin, M.D., M.P.H., a cardiology fellow and assistant professor of medicine at the Mayo Clinic.
The study was presented at the American Heart Association's Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism 2012 Scientific Sessions. Information regarding funding and conflicts of interest was unavailable.