Skipping just an hour and a half of sleep each night could see you gain a pound of weight every six weeks – and the blame lies not with late-night snacking but with the extra time spent sitting down, according to a new study from Columbia University.
Researchers at the Vagelos College of Physicians and Surgeons recruited nearly 100 adults who normally slept seven to eight hours a night and asked them to delay their bedtime by 90 minutes for a six-week period. The results, published Monday, showed that on average participants gained one pound and their daily sedentary time increased by 17 minutes. For men and postmenopausal women – groups already at higher risk of being overweight – that inactivity jumped to nearly 30 minutes a day.
“Losing 1.5 hours of sleep a night for six weeks leads to 1lb weight gain due to increased inactivity, study finds.”
“Even when we accounted for the fact that they were awake longer when sleep was shortened, participants spent more time being inactive than when they got adequate sleep,” said Faris Zuraikat, an assistant professor at Columbia’s Department of Medicine and Institute for Human Nutrition. “This is notable, as people who are more sedentary have elevated risk for chronic diseases.”
While a single pound may not sound alarming, the researchers warn that the effect compounds. “When extrapolated to a full year, we would expect that losing less than an hour and a half of sleep per night could result in clinically meaningful weight gain,” Zuraikat added.
During the study, participants also spent a separate six-week phase getting their normal amount of sleep. Activity and sleep were tracked using wrist monitors, and researchers measured body weight, waist circumference, body composition and levels of hunger-related hormones. The same group had previously shown that restricting sleep by 80 minutes for six weeks increased insulin resistance in women and boosted inflammatory cells in the hearts of those already at risk.
“Our study shows that getting adequate sleep may help reduce the risk of weight gain and obesity-related conditions like heart disease and diabetes,” said senior author Marie-Pierre St-Onge, a professor of nutritional medicine at Columbia. The team believes about a third of adults regularly get too little sleep, making the findings relevant to millions.