We've all heard about the importance of getting a good night's sleep, and now scientists offer more evidence to back that up. A new study found that people who get less sleep may be inclined to eat more, move less and gain weight.
Scientists at the Mayo Clinic in Rochester, Minn., studied a group of 17 healthy volunteers between the ages 18 and 40 for a week in their homes, monitoring how much each one typically slept and ate. Then, they brought the volunteers into the clinic's research lab for eight days: Half of the volunteers were allowed to sleep according to their usual pattern, and the other half got only two-thirds of their usual shut-eye.
All the volunteers were allowed to eat as much food as they wanted from the hospital cafeteria or from outside the research center. The researchers also measured how much energy each volunteer expended each day.
The sleep-deprived participants wolfed down an average of 549 calories beyond their usual intake but burned no more calories than their well-rested peers.
"A lot of people have this idea that if they're up late, working hard, they're burning more energy. But we found no change in how much they moved when sleep deprived," said Dr. Andrew Calvin, lead author of the study and an assistant professor of medicine at the Mayo Clinic. "They're consuming an additional 549 calories per day, but not burning any of them off."
Those excess of unburned calories is a surefire way to gain weight, which numerous studies have connected to a variety of chronic health problems.
The volunteers who got less sleep also had higher levels of leptin, a hormone that suppresses appetite, and lower levels of ghrelin, a hormone that stimulates appetite, in their blood. The findings seem counterintuitive to what researchers would expect in people who are hungrier, but Calvin said the hormones were most likely an outcome, rather than a cause of people eating more.
Scientists have previously studied the physical downsides of getting too little sleep.
In 2011, Australian researchers found that adolescents and teenagers were more likely to be slimmer if they went to bed earlier, while those who stayed up late were more likely to engage in sedentary activities.
Previous studies have also found that workers covering late and overnight shifts were more likely to be obese and have type 2 diabetes, which may be associated with unhealthy eating habits, according to an editorial published in December.
The connection between sleep and weight may be important for the more than one-quarter of Americans who get six hours of sleep or less every night. Calvin said the future research on how sleep affects eating habits may give scientists useful insights into two of America's biggest health problems: sleep deprivation and obesity.
"This study, while small, suggests that these two may indeed be linked, and if the findings are confirmed, they may suggest that sleep is a powerful factor in how much we eat and our chances of gaining weight," he said.