Overview
- A pooled randomized crossover analysis published in Annals of Internal Medicine found that shortening sleep by roughly 80–90 minutes per night for six weeks caused an average weight gain of about 1 pound and an increase in sedentary time.
- The trial pooled two six‑week phases involving 95 adults who normally slept 7–8 hours and used wrist actigraphy, body measurements and blood tests to compare usual sleep with delayed bedtimes.
- Sedentary time rose by about 17 minutes per day overall and by nearly 30 minutes per day for men and for postmenopausal women, a change the authors link to lower daily movement rather than more exercise.
- Related analyses of the same participants found signals of metabolic and heart risk, including increased insulin resistance in some women and inflammatory cell influx to the heart after sleep loss.
- Study leaders emphasize the short‑term effect is modest but say it could accumulate over months to years and call for trials that test whether restoring sleep reverses weight, hormonal and cardiometabolic changes.