A new clinical study suggests that a fairly small, sustained drop in nightly sleep can lead to measurable weight gain and more sedentary behavior. Researchers at Columbia University combined data from two randomized crossover trials to study how reducing sleep by about 78 minutes per night for six weeks affected adults at elevated cardiometabolic risk.
Study design and measurements
Ninety-five adults age 20 and older who typically slept at least seven hours nightly took part. Each person experienced two six-week conditions: “adequate sleep,” when they kept their usual schedule (≥7 hours), and “sleep restriction,” when bedtime was delayed by roughly 1.5 hours to cut nightly sleep by about 90 minutes. The trials used a crossover design so each participant served as their own control.
Researchers monitored sleep and activity with wrist actigraphy and sleep diaries, and performed detailed assessments before and after each condition. Measurements included body weight, waist circumference, whole-body MRI for fat and muscle volumes, blood tests for hormones related to hunger and energy balance (leptin, ghrelin, GLP-1), and, in a smaller group, total daily energy expenditure measured by doubly labeled water.
Key findings
– Average nightly sleep was reduced by about 78 minutes in the sleep-restricted condition. Over six weeks, participants gained an average of 0.45 kg (nearly 1 pound) compared with the adequate-sleep condition.
– Waist circumference increased about 0.5 cm during sleep restriction, suggesting some gain around the abdomen. MRI showed an increase in whole-body volume but no consistent shift in the proportion of fat versus muscle.
– Leptin levels rose with sleep restriction, consistent with increased energy stores. Ghrelin tended to decrease slightly but not significantly; GLP-1 showed no change.
– Participants spent roughly 17 more minutes per day being sedentary during the sleep-restricted weeks. Time in moderate-to-vigorous physical activity did not change. In the subgroup measured with doubly labeled water, total daily energy expenditure did not differ significantly between conditions.
Interpretation
The pattern observed suggests that modest, chronic sleep loss can lead to small but measurable weight gain and more sedentary time. Because energy expenditure did not drop significantly in the measured subset, the researchers propose that increased calorie intake and reduced incidental movement (more sitting) likely explain the weight gain rather than a large decline in calories burned.
Expert perspective
Clinicians not involved in the study emphasize that disrupted or insufficient sleep affects hunger regulation, impulse control, insulin sensitivity, and stress hormones—factors that can promote overeating and abdominal fat storage. Sleep loss also tends to reduce spontaneous physical activity and recovery from exercise, compounding weight and metabolic risk.
Practical tips to protect sleep and weight
– Aim for a consistent sleep schedule, going to bed and waking at about the same times each day.
– Build a calming bedtime routine: reading, a warm shower, light stretching, or relaxing music.
– Limit screen use and work-related tasks before bed to help wind down.
– Avoid late-day caffeine and be cautious with alcohol near bedtime, as it can fragment sleep.
– Keep the bedroom dark, quiet, and comfortably cool.
– Exercise regularly, but avoid very intense workouts right before bed.
– If you struggle to fall or stay asleep or feel unrefreshed despite sufficient time in bed, consult a healthcare professional to evaluate possible sleep disorders.
Bottom line
Even a relatively small nightly sleep deficit—about 78 minutes—sustained over several weeks was associated with nearly a pound of weight gain, a modest increase in waist size, and more sedentary time in this trial. Prioritizing regular, restorative sleep is an important and often overlooked component of healthy weight management and metabolic health.
