Mixed
In older adults (aged 64+), nighttime sleep duration of 7-7.9 hours is associated with the lowest mortality risk, while sleeping ≥10 hours in men and ≥8 hours in women significantly increases all-cause mortality.
If you are over 64, aim for 7 to 7.9 hours of nighttime sleep. Sleeping significantly longer (10+ hours for men, 8+ for women) is linked to higher death risk, likely due to underlying health issues rather than the sleep itself. Taking an afternoon nap does not increase or decrease this risk, so you can nap without worry if it helps you feel rested.
Compared to older adults sleeping 7~7.9 hours at night, those with longer sleeping time (≥ 10 hours in males and ≥ 8 hours in females) had a significantly higher risk of total mortality.
Why this rating
Prospective cohort study with large sample size (n=3079) and long follow-up (10 years), though observational and subject to residual confounding.
Source
Nighttime Sleep, Chinese Afternoon Nap, and Mortality in the Elderly
Tzuo-Yun Lan et al. · SLEEP · 2007
DOI 10.1093/sleep/30.9.1105
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