New research from Columbia University found that adults who cut their sleep by about 80 minutes for six weeks packed on a pound (0.45 kg) and moved less during the day.
The mild sleep deprivation common to nearly a third of American adults may be quietly driving long-term weight gain, not through overeating, but inactivity. Image credit: Sweet Briar College.
Much of what’s known about the link between insufficient sleep and obesity is based on small, brief studies of people who endured severe sleep restriction.
Such studies show that severe sleep deprivation leads to changes in appetite and overeating, which can contribute to weight gain over time.
But most people cannot tolerate severe sleep deprivation for more than a few days.
“These studies only show us what happens under the most extreme conditions and don’t tell us if mildly sleep-deprived people, like a lot of Americans who get 5 or 6 hours of sleep a night, will gain weight,” said Columbia University’s Professor Marie-Pierre St-Onge.
To investigate the effects of chronic mild sleep deprivation, a sleep pattern adopted by roughly 30% of adults, Professor St-Onge and colleagues recruited 95 adults who usually get 7-8 hours of sleep.
Participants were instructed to delay their normal bedtime by 90 minutes for one six-week phase and to get the usual amount of sleep for another six-week phase.
Sleep and activity levels were measured throughout each phase with a wrist monitor, along with changes in body weight, waist circumference, body composition, and fasting levels of several hormones known to increase or suppress appetite.
“While the one-pound weight gain observed with modest sleep curtailment is not overwhelming, it is important to remember this is occurring over just six weeks,” said Dr. Faris Zuraikat, also from Columbia University.
“Our study was designed to mimic sleep patterns that most adults experience chronically.”
“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.”
Sedentary time also increased by an average of 17 minutes per day during the sleep-restriction phase overall, and by nearly 30 minutes per day for men and postmenopausal women.
“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,” Dr. Zuraikat said.
“This is notable, as people who are more sedentary have elevated risk for chronic diseases.”
“Our study shows that getting adequate sleep may help reduce the risk of weight gain and obesity-related conditions like heart disease and diabetes,” Professor St-Onge said.
“People tend to gain weight over the course of their adulthood, and obesity is a major risk factor for heart disease.”
“But focusing on eating a healthier diet and getting more physical activity to offset weight gain is simplistic and can be difficult to maintain.”
The study was published this month in the Annals of Internal Medicine.
_____
Faris M. Zuraikat et al. Prolonged Short Sleep and Its Effect on Body Weight and Composition: A Pooled Analysis of Randomized Trials. Annals of Internal Medicine, published online July 7, 2026; doi: 10.7326/ANNALS-25-01660
