A new study led by the University of Colorado Boulder, performed in collaboration with the CU Anschutz Medical Campus, suggests that sufficient sleep could be a significant strategy in the battle against 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 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.
In the new study, published in the Proceedings of the National Academy of Sciences, the researchers show that, while staying awake longer requires more energy, the quantity of food study participants ate more than made up for the extra calories they 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."
For the study, researchers monitored 16 young, healthy adults who stayed 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 — along with a room that is sealed allowing researchers to measure how much energy participants are using depending on the amount of oxygen they breathe in and the amount of carbon dioxide they breathe out.
All study participants spent 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. But after the first few days, the study group was split into two categories: 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, they 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 five per cent more energy than those who slept up to nine hours a night, but they consumed six per cent 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 findings provide additional evidence that overeating at night may contribute to weight gain.
"When people are sleep-restricted, our findings show they eat during their biological night-time when internal physiology is not designed to be taking in food," said Wright, who is already working on a new study to better determine the implications of when people are eating not just what they're eating.
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