Multiple Health Outcomes of Daytime Napping: A Comprehensive Umbrella Review

Objectives: This umbrella review aimed to clarify the dose-response relationship between napping duration and multiple health outcomes. Methods: Following JBI guidelines, the review included studies from PubMed, Web of Science, the Cochrane Library, and EMBASE. Data on health outcomes, effect sizes, and study characteristics were extracted, and the quality of the studies was assessed using AMSTAR-2 and GRADE. A random effects model and a sensitivity analysis were used to evaluate the associations. Results: This umbrella review identified 16 meta-analyses encompassing 244 health-related outcomes. Napping for <60 min maximizes cognitive enhancement (SMD = 0.69, 95% CI: 0.37-1.00) and reduces fatigue, while minimizing the risk of all-cause mortality and chronic diseases. Napping for >60 min correlates with a 30% higher risk of coronary heart disease and a 20% increased risk of diabetes and obesity; short naps (20-30 min) improve athletic performance (SMD = 0.99, 95% CI: 0.67-1.31) and recovery, particularly in sleep-deprived individuals. Conclusion: Limiting nap duration to ≤60 min may optimize cognitive and physical benefits while reducing chronic disease risks. For individuals with chronic conditions, it is prudent to avoid prolonged naps (>60 min) and prioritize nighttime sleep quality.