GENERAL MEDICINE
Excessive daytime napping linked with increased mortality risk
Regular napping around noon and in the early afternoon was associated with an increased risk of all-cause mortality
June 18, 2025
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Timing, duration and variability of daytime napping are associated with an increased risk for mortality in middle- to older-aged adults, new research has shown.An analysis of UK Biobank data, which included more than 86,000 non-shift workers, showed that longer naps, greater variability in daytime napping duration, and higher percentages of naps around noon and in the early afternoon are associated with an increased risk for all-cause mortality.“Our study fills a gap in knowledge by showing that it’s not just whether someone naps but how long, how variable, and when they nap may be meaningful indicators of future health risk,” said lead investigator Chenlu Gao, Division of Sleep Medicine, Harvard Medical School and Massachusetts General Hospital in Boston.For the study, the researchers examined whether actigraphy-measured objective daytime napping behaviors predict all-cause mortality in 86,565 non-shift workers.The cohort had a mean age of 63 years at baseline, and 57% were women. They were monitored by actigraphy for 7 days, and daytime napping was defined as sleep between 9 AM and 7 PM.Median nap duration was 0.40 h/d, with 34% of naps taken between 9 and 11 AM, 10% between 11 AM and 1 PM, 14% between 1 and 3 PM, 19% between 3 and 5 PM, and 22% between 5 and 7 PM.During a follow-up period of up to 11 years, 5189 (6.0%) participants died. Overall, as individuals aged, naps tended to become longer and more irregular, with timing shifting toward the afternoon.After adjusting for potential confounders, including demographics, BMI, smoking, alcohol use, and nighttime sleep duration, longer nap duration was associated with an increased risk for mortality (hazard ratio [HR], 1.20 for 1 SD; P < .0001).Greater intraindividual variability (HR, 1.14 for 1 SD; P < .0001) and a higher percentage of naps between 11 AM and 1 PM (HR, 1.07 for 1 SD; P = .0005) and between 1 and 3 PM (HR, 1.07 for 1 SD; P = .0002) were also associated with an increased risk for mortality.