A new analysis in Annals of Internal Medicine suggests that going to bed about an hour and a half later than usual, for just six weeks, was enough to nudge body weight up. The gain was small, but the researchers say it could add up.
What the researchers did
The study, led by Columbia University researchers, pooled data from randomized trials involving 95 adults who normally sleep 7 to 8 hours a night. In one six-week phase, participants were told to delay their usual bedtime by 90 minutes. In another six-week phase, they slept as they normally do. Wrist monitors tracked sleep and activity, and the team also measured weight, waist size, body composition and appetite-related hormones.
What they found
During the shortened-sleep phase, participants gained about one pound (0.45 kg) on average. Columbia’s summary describes the sleep cut as around 80 minutes a night. Sedentary time rose by an average of 17 minutes a day, and by nearly 30 minutes a day among men and postmenopausal women.
Lead author Faris Zuraikat called the one-pound gain “not overwhelming” over six weeks, but said that if the pattern continued for a year, losing less than an hour and a half of sleep a night could plausibly lead to clinically meaningful weight gain. That year-long figure is the authors’ projection, not something the study measured.
The catch
The public summaries leave out a lot: they give no numbers for fat mass, waist size or hormones, no age range, and no listed limitations, and we could not read the full paper. The sleep loss was assigned by researchers rather than chosen by participants, and each phase lasted only six weeks, so the year-long claim is an extrapolation. One pound is also small enough to vary with ordinary day-to-day habits.
What it means for you
The finding fits a broader idea: when sleep gets short, people tend to move less, and that may be part of the story. If you routinely stay up later than you need to, the study is one more reason to treat bedtime as something worth protecting. Our earlier look at a study linking short daily exercise to deeper sleep covers the other direction.
This article is for general information, not medical advice.
More on Contoh
- Just 10 Minutes of Daily Exercise Was Linked to Deeper Sleep in a Study of Young Adults
- Late-Night Eating Linked to Higher Risk of Fatty Liver Disease and Cirrhosis in a Study of 199,000 Adults
Sources
- Columbia University Irving Medical Center: Skimping on Sleep Leads to Weight Gain
- News-Medical: Six Weeks of Shorter Sleep Increases Weight and Sedentary Time
- Sci.News: Losing Even 80 Minutes of Sleep a Night Linked to Weight Gain
- Annals of Internal Medicine: Zuraikat et al., DOI 10.7326/ANNALS-25-01660