Less sleep leads to eating more, weight gain: study

Sleeping just five hours a night over a workweek and having unlimited access to food caused participants in a new study led by the University of Colorado Boulder to gain nearly two pounds of weight.

The study, performed in collaboration with the CU Anschutz Medical Campus, suggests 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 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.

Previous research has shown that a lack of sleep can lead to weight gain, but the reasons for extra pounds were unclear. In the new study, published 11 March 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.''

For the study, researchers 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.