redOrbit Staff & Wire Reports – Your Universe Online
While previous studies have uncovered a link between a lack of sleep and weight gain, new research published in Monday´s edition of the journal Proceedings of the National Academy of Sciences (PNAS) has discovered the reasons why the phenomenon occurs.
Individuals who sleep just five hours each night over the course of an entire workweek and have unlimited access to food can put on nearly two pounds of weight, the researchers said. They concluded that being forced to stay awake the extra hours required more energy, which in turn led the study participants to consume more food — and to actually eat more than their body needed to keep functioning.
“I don´t think extra sleep by itself is going to lead to weight loss,” lead researcher Kenneth Wright, director of the Sleep and Chronobiology Laboratory at the University of Colorado Boulder, said in a statement. “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,” he added, noting that more study would be required to support that hypothesis. “Just getting less sleep, by itself, is not going to lead to weight gain. But when people get insufficient sleep, it leads them to eat more than they actually need.”
Wright and his associates monitored 16 young, lean, healthy adults at over a period of two weeks. Each study participant slept in a specialized location that allowed the researchers to exert control over the amount of time the subjects slept, as well as monitor how much energy they exerted based on the amount of oxygen they inhaled and the amount of carbon dioxide they exhaled.
For the first three days, each study participant was given the opportunity to sleep nine hours each night and eat portion-controlled meals designed to give them only the amount of calories needed to maintain weight. This was done to establish a baseline measurement, but within a few days, the 16 subjects were split into two different groups. One group was allowed to sleep just five hours for a period of five days, and the other was allowed to continue sleeping for the entire nine-hour period.
“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,” the university explained. “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.”
Wright and his colleagues also observed that those who slept for just five hours were more likely to eat smaller breakfasts and then binge on after-dinner snacks. In fact, the researchers said, the total amount of calories of those nighttime snacks were higher than the caloric content of any of the regularly scheduled daily meals — a discovery that they believe helps demonstrate that nocturnal overeating could contribute to weight gain.
The study also detected differences in the way men and women responded to having access to unlimited quantities of food. Even with full nights of sleep, male subjects were more likely to gain weight when they could eat as much as they want. Females, on the other hand, tended to just maintain their current bodyweight when they were allowed to sleep for nine hours, no matter how much they were allowed to consume. Both genders gained weight when they were only allowed to sleep for a maximum of five hours each night, however.