Certain objectively measured daytime napping behaviors are associated with an increased risk of mortality for middle-to-older aged adults, according to a new study presented at Sleep 2025.
Results show that the median nap duration was 0.40 hours per day. Thirty-four percent of naps were taken between 9 am and 11 am, 10% were taken between 11 am and 1 pm, 14% were taken between 1 pm and 3 pm, 19% were taken between 3 pm and 5 pm, and 22% were taken between 5 pm and 7 pm. An analysis found that longer naps, greater variability in daytime nap duration, and higher percentages of naps around noon and in the early afternoon are associated with greater mortality risks.
RT’s Three Key Takeaways
- Longer and Irregular Naps Increase Risk: Objectively measured long and inconsistent daytime naps were associated with higher mortality risk in middle-to-older aged adults.
- Midday and Early Afternoon Naps Raise Concerns: Napping around noon and early afternoon was unexpectedly linked to greater mortality, challenging current napping guidelines.
- Daytime Sleep May Signal Underlying Health Risks: Findings suggest that tracking daytime sleep behaviors via actigraphy could help identify adults at increased health risk and inform personalized interventions.
“In evaluating the results of the sleep study, we were surprised by how common napping was among middle-to-older aged adults, how much their daytime sleep patterns varied across days, and when during the day they are sleeping,” said lead author Chenlu Gao, a postdoctoral research fellow at Massachusetts General Hospital in Boston. “People who slept longer during the day, had irregular daytime sleep patterns, or slept more around midday and early afternoon were at greater risk, even after accounting for health and lifestyle factors.”
The American Academy of Sleep Medicine encourages healthy adults to limit naps to no longer than 20-30 minutes in the early afternoon. While a brief “power” nap can improve daytime alertness and performance, naps of 30 minutes or longer may cause a person to feel groggy after waking up. This grogginess, or “sleep inertia,” can delay the short-term performance benefits of a nap.
“Interestingly, the data that shows risks associated with napping around midday and early afternoon contradicts what we currently know about napping, so further research on that link could be warranted,” Gao added.
The study sample comprised 86,565 non-shiftworking participants in the UK Biobank with an average baseline age of 63 years; 57% were women. They were monitored by actigraphy for seven days, and daytime napping was defined as sleep between 9 am and 7 pm. Mortality data were obtained from national registries. There were 5,189 (6.0%) participants who died during a follow-up period of up to 11 years. Results were adjusted for potential confounders including demographics, body mass index, smoking, alcohol consumption, and nighttime sleep duration.
Gao noted that the results are important because they highlight the potential significance of considering daytime sleep behaviors in the risk stratification of mortality in adults. However, the study has some limitations. Because it relied on actigraphy, which detects movement but not brain activity, quiet wakefulness may have been misclassified as sleep. Additionally, defining daytime napping as sleep between 9 am and 7 pm could have inadvertently included portions of participants’ primary sleep episodes, potentially affecting the accuracy of nap classification.
“Incorporating actigraphy-based daytime sleep assessments into clinical and public health practices may provide novel opportunities for early risk identification and personalized interventions to promote longevity,” Gao said.
