No one wants either of the above outcomes
Add this feather to our you-need-to-sleep-more-cap: “Just getting less sleep, by itself, is not going to lead to weight gain,” says Kenneth Wright, director of CU-Boulder’s Sleep and Chronobiology Laboratory, which led a new study. “But when people get insufficient sleep, it leads them to eat more than they actually need.”
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, 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.
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.
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. The total amount of calories consumed in evening snacks was larger than the calories that made up any individual meal.
Interestingly, men gained some weight even with adequate sleep when they could eat as much as they wanted, while women simply maintained their weight when they had adequate sleep, regardless of how much food was available. Both men and women gained weight when they were only allowed to sleep for up to five hours.