Skipping an hour and a bit of sleep for six weeks is the kind of thing most of us do without noticing. In a pooled analysis of two randomized crossover trials, it was enough to move the scale. When 95 adults cut their sleep by about 78 minutes a night, they gained weight, added to their waistline, and spent more time sitting than when they slept enough.[1]
How the trials worked
Both trials enrolled adults aged 20 or older with at least seven hours of habitual sleep and elevated cardiometabolic risk. Every participant did two six-week phases, separated by a washout of several weeks: one with adequate sleep and one with sleep cut by 1.5 hours a night. A crossover design like this matters because each person is compared with themselves. Researchers measured weight, waist circumference, body volume, and fat with MRI, and tracked appetite-related biomarkers and behavior.[1]
What changed
- Sleep: down by 78.4 minutes per night (95% CI, 73.3 to 83.5).
- Body weight: up 0.45 kg (CI, 0.33 to 0.57), roughly one pound, in six weeks.
- Waist circumference: up 0.52 cm (CI, 0.25 to 0.79).
- Whole-body volume: up 0.56 L (CI, 0.19 to 0.93).
- Leptin: up 2.03 ng/mL (CI, 0.38 to 3.68). Leptin is a hormone made by fat tissue that is tied to appetite and energy balance.
- Sedentary time: up 17.2 minutes per day (CI, 11.7 to 22.7).
The authors conclude that prolonged, moderately short sleep may lead to weight gain, and that weight management and cardiometabolic disease prevention programs should consider adding sleep strategies.[1]
How big is this, honestly?
Modest. The authors list that themselves: effect sizes were small, the six weeks may have been too short to show changes in body composition, and the study had limited power to look at individual differences.[1] The participants were adults at elevated cardiometabolic risk, so the results may not carry over to everyone. Still, a pound in six weeks is a signal worth taking seriously, especially because the pattern, an hour or so short on most nights, is common.
What to do with it
- Treat sleep like part of your weight plan. If you are doing everything right with food and exercise and the scale creeps up, check your sleep before you tighten the diet.
- Protect one anchor. Fix your wake time first, then work backward and move bedtime earlier in 15-minute steps.
- Plan for the extra sitting. Short sleepers in the trial moved less. After a short night, schedule a walk rather than relying on willpower.
- Aim for the 7-plus hours these participants started from. That was their normal, and it was the comparison group.
References
[1] Zuraikat FM, Scaccia SE, Cochran JA, Cheng B, Diaz KM, Creasy SA, et al. Prolonged Short Sleep and Its Effect on Body Weight and Composition: A Pooled Analysis of Randomized Trials. Ann Intern Med, 2026;179(8):1085-1093. Population: 95 adults aged 20 or older with elevated cardiometabolic risk and habitual sleep of 7 or more hours; pooled analysis of 2 randomized crossover trials (NCT02960776, NCT02835261); six weeks of adequate sleep versus six weeks of sleep restriction by 1.5 hours per night, separated by a multiweek washout. DOI: https://doi.org/10.7326/ANNALS-25-01660. Finding as used: sleep fell by 78.4 minutes per night (95% CI, -83.5 to -73.3); body weight rose 0.45 kg (CI, 0.33 to 0.57), waist circumference 0.52 cm (CI, 0.25 to 0.79), whole-body volume 0.56 L (CI, 0.19 to 0.93), leptin 2.03 ng/mL (CI, 0.38 to 3.68), and sedentary time 17.2 minutes per day (CI, 11.7 to 22.7), all relative to adequate sleep; limitations were a possibly too short intervention to identify body composition changes, limited power for individual differences, and modest effect sizes; the authors conclude prolonged moderately short sleep may lead to weight gain and weight management programs should consider incorporating sleep strategies. ↑︎
Kurt Greiner
Kurt is a digital strategist and IT professional blending emerging technology with practical application, exploring how individuals can leverage modern tools to navigate the second half of life with purpose.
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