How Less Sleep Might Make You Fatter

lack of sleep may be connected to weight gainLast year a study led by the University of Colorado Boulder found that sleeping just five hours a night over a workweek and having unlimited access to food caused participants to gain nearly two pounds of weight. Researchers suggest that sufficient sleep could help battle the obesity epidemic.

“I don’t think extra sleep by itself is going to lead to weight loss,” said Kenneth Wright, director of CU-Boulder’s Sleep and Chronobiology Laboratory, which led the Colorado study. “Problems with weight gain and obesity are much more complex than that. But I think it could help. If we can incorporate healthy sleep into weight-loss and weight-maintenance programs, our findings suggest that it may assist people to obtain a healthier weight.” But further research is needed to test that hypothesis, Wright added.

Researchers at CU-Boulder monitored 16 young, lean, healthy adults who lived for about two weeks at the University of Colorado Hospital, which is equipped with a “sleep suite” for controlling sleep opportunities — by providing a quiet environment and by regulating when the lights are on and off — and a sealed room that allows researchers to measure how much energy participants are using based on the amount of oxygen they breathe in and the amount of carbon dioxide they breathe out.

All participants spent the first three days with the opportunity to sleep nine hours a night and eating meals that were controlled to give participants only the calories they needed to maintain their weight in order to establish baseline measurements. But after the first few days, the participants were split into two groups: one that spent five days with only five hours to sleep in and one that spent five days with nine hours of sleep opportunity. In both groups, participants were offered larger meals and had access to snack options throughout the day ranging from fruit and yogurt to ice cream and potato chips. After the five-day period, the groups switched.

On average, the participants who slept for up to five hours a night burned 5 percent more energy than those who slept up to nine hours a night, but they consumed 6 percent more calories. Those getting less sleep also tended to eat smaller breakfasts but binge on after-dinner snacks. In fact, the total amount of calories consumed in evening snacks was larger than the calories that made up any individual meal. The current findings add to the growing body of evidence showing that overeating at night may contribute to weight gain.

Previous research has shown that a lack of sleep can lead to weight gain, but the reasons for extra pounds were unclear. In this study, published March 11, 2013 in the Proceedings of the National Academy of Sciences, the researchers show that, while staying awake longer requires more energy, the amount of food study participants ate more than offset the extra calories burned.

“Just getting less sleep, by itself, is not going to lead to weight gain,” Wright said. “But when people get insufficient sleep, it leads them to eat more than they actually need.”

As if that weren’t compelling enough, a new study out of University College London found that very young children who sleep fewer than 10 hours a day consumed more daily calories than their peers who slept more than 13 hours a day.

This latest study provides further evidence that sleep can strongly influence our eating habits and risks for weight gain, and that sleep can be an important therapeutic tool in losing weight and keeping it off.