Long-term sleeping during the day damages human health
Multiple recent studies and umbrella reviews indicate that prolonged or excessive daytime sleeping (typically over 30 to 60 minutes) is associated with negative health outcomes, including increased risks of metabolic syndrome, chronic disease, biological aging, and all-cause mortality.
The claim specifies that long-term sleeping during the day damages human health. Multiple large-scale prospective cohort studies, umbrella reviews, and Mendelian randomization analyses demonstrate that prolonged or frequent daytime napping is causally or observationally linked to adverse health outcomes such as metabolic syndrome, cardiovascular disease, accelerated biological aging, and mortality, while only very short or moderate napping shows occasional nuanced benefits in specific subgroups.
Zhang B, Liu W, Wang J, Zhang L, Wang K, Wang P. Sleep duration, daytime napping and the risk of incident metabolic syndrome vary by age and sex: findings from the China health and retirement longitudinal study.. 2025. https://doi.org/10.1186/s12889-025-21915-0
Longer daytime napping (>30 min/day) was significantly associated with a higher risk of developing metabolic syndrome.
Hou QQ, Liao HM, Tian WQ, Yao QY, Qin DY, Yuan XQ, Yao W, Du YY, Li J, Wang Y, Zeng Q, Deng TR, Liu C, Li YF. Associations between daytime napping and parameters of ovarian reserve among women undergoing assisted reproductive technology.. 2026. https://doi.org/10.1186/s12905-026-04316-2
Daytime napping of one hour or less was inversely associated with certain hormone levels, suggesting a potentially beneficial profile for ovarian reserve under specific conditions.
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Pengqiang Du, Jiqian Li, Zixin Hua, Yiqi Sun, Siyang Song, Yin Liao, Sheng Cheng, Xingang Li. Multiple Health Outcomes of Daytime Napping: A Comprehensive Umbrella Review. 2026. https://doi.org/10.3389/phrs.2026.1609013
Napping for >60 minutes correlates with a 30% higher risk of coronary heart disease and a 20% increased risk of diabetes and obesity.
Zhang Z, Wang X, Qiu H, Luo Q, Jiang C, Yang G. Distinct roles of chronotype, daytime napping, and sleep duration in biological and functional aging: a univariable and multivariable Mendelian randomization study.. 2026. https://doi.org/10.1186/s13148-026-02068-2
Mendelian randomization analysis indicates that excessive daytime napping causally influences accelerated biological aging indicators like GrimAge and frailty.
Gao C, Cai R, Zheng X, Gaba A, Yu L, Buchman AS, Bennett DA, Gao L, Hu K, Li P. Objectively Measured Daytime Napping Patterns and All-Cause Mortality in Older Adults.. 2026. https://doi.org/10.1001/jamanetworkopen.2026.7938
Actigraphy-measured longer and more frequent daytime napping in older adults are associated with higher all-cause mortality.
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