Losing Just 80 Minutes of Sleep a Night Makes You Gain Weight, Six-Week Study Finds

A Columbia University study published in the Annals of Internal Medicine finds that chronic mild sleep deprivation — just 80 minutes less per night — leads to measurable weight gain and increased sedentary behavior over six weeks.

A new study from Columbia University has found that cutting sleep by just 80 minutes a night — roughly the amount lost by the 30% of American adults who get only 5 or 6 hours — leads to weight gain within six weeks.

The randomized trial, published July 6 in the Annals of Internal Medicine, followed 95 adults who normally sleep 7 to 8 hours. Participants were instructed to delay their bedtime by 90 minutes for one six-week phase. On average, they gained about one pound and spent 17 more minutes per day being sedentary — a figure that rose to nearly 30 minutes for men and postmenopausal women.

"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 Marie-Pierre St-Onge, professor of nutritional medicine at Columbia University Vagelos College of Physicians and Surgeons and lead author of the study.

Unlike previous research that examined extreme sleep deprivation — typically just 4 hours a night for a few days — this study looked at the kind of mild, chronic sleep loss that millions of people experience every night. "These studies only show us what happens under the most extreme conditions and don't tell us if mildly sleep-deprived people will gain weight," St-Onge noted.

The findings are part of a broader body of research from St-Onge's lab, funded by the American Heart Association and the National Institutes of Health. Earlier work on subsets of the same participants found that women with elevated cardiometabolic risk developed increased insulin resistance after mild sleep restriction, while men and women with elevated heart risk showed an influx of inflammatory cells in the heart.

"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 co-author Faris Zuraikat. "This is notable, as people who are more sedentary have elevated risk for chronic diseases."

The researchers say the next step is to study whether improving sleep in habitually sleep-deprived people can reverse these effects.