Research
Energy balance
Long sleep duration (≥ 9 hours) is associated with increased weight gain in men, potentially due to reduced energy expenditure from time in bed or underlying conditions like sleep apnea.
Sleeping 9 hours or more is also linked to weight gain in men, possibly because you are less active while in bed or because of undiagnosed sleep disorders like apnea. Aim for the 'Goldilocks' zone of 7-8 hours for optimal metabolic health.
ModerateSupportsMEDIUM confidence
The present study also showed that sleep duration of over 9 h was significantly associated with weight gain.
Why this rating
Association is significant for weight gain (BMI change) but not for incident obesity (OR 1.42, not statistically significant). Mechanism is speculative.
Source
Association of Short Sleep Duration with Weight Gain and Obesity at 1-Year Follow-Up: A Large-Scale Prospective Study
Mayumi Watanabe et al. · SLEEP · 2010
DOI 10.1093/sleep/33.2.161
cohort · n=34852Cited 259×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
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