The Association Between Sleep and Obesity in Adults: An Umbrella Review of Meta‐Analyses

ABSTRACT Background and Aims Short sleep duration, poor sleep quality, and circadian disruption have been linked to obesity, but the proliferation of systematic reviews with meta‐analyses (SRMAs) has fragmented the evidence. No prior umbrella review has synthesized all sleep characteristics exclusively in adults or formally graded the credibility of associations. We aimed to evaluate the association between various sleep characteristics and obesity‑related outcomes in adults. Methods We conducted an umbrella review of SRMAs. PubMed, Embase, Cochrane Database of Systematic Reviews, Scopus, CINAHL, and Epistemonikos were searched from inception to March 1, 2026. We included SRMAs examining adults (≥ 18 years) reporting any sleep exposure and obesity outcomes. Methodological quality was assessed using AMSTAR 2. Overlap of primary studies was quantified with the corrected covered area (CCA). Evidence was graded using Ioannidis criteria. Results Sixteen SRMAs encompassing approximately 13.8 million participants were included. Primary study overlap was very low (overall CCA = 0.024). Short sleep duration was associated with a 40% increased odds of obesity (pooled OR 1.40, 95% CI 1.27–1.55; I2 = 83.7%). Long sleep showed a modest association (OR 1.05, 95% CI 1.02–1.08; I2 = 0%). Both were classified as Class III (Suggestive) evidence. Daytime napping, social jetlag, and insomnia symptoms met only Class IV (Weak) criteria. Objective sleep measurement (polysomnography) yielded substantially larger effects (OR 2.70, 95% CI 1.80–4.05) than self‑report (OR 1.14, 95% CI 0.98–1.33). AMSTAR 2 assessment revealed two high‑quality, four moderate, nine low, and one critically low review. Conclusions Short and long sleep durations are suggestively associated with obesity in adults, with short sleep showing a stronger effect. Other sleep characteristics have weak or limited evidence. Clinicians should consider sleep duration a potentially modifiable risk factor for obesity. PROSPERO Registration CRD420261326462.