A newly presented study at the SLEEP 2025 annual meeting has shed light on the intriguing link between daytime napping behaviours and mortality risk in middle-aged to older adults. The research, which relied on objective measurements of sleep patterns, found that certain daytime napping habits, specifically longer nap durations, higher day-to-day variability in nap lengths, and an increased frequency of naps around midday and the early afternoon, were significantly associated with a greater risk of death. These findings challenge some of the long-held assumptions about the potential benefits of napping in older populations, suggesting that the timing, duration, and consistency of naps could be more consequential than previously thought.
The data gathered for this investigation revealed that the median nap duration among participants was approximately 0.40 hours each day. Nap timing varied considerably across the day, with the highest percentage of naps, 34%, occurring between 9 a.m. and 11 a.m. In contrast, only 10% of naps were taken between 11 a.m. and 1 p.m. The frequency increased later in the day, with 14% of naps between 1 p.m. and 3 p.m., 19% between 3 p.m. and 5 p.m., and 22% between 5 p.m. and 7 p.m. Such distribution suggests a noteworthy trend of increased napping as the day progresses, raising questions about how these patterns might interact with the body’s natural circadian rhythms and overall sleep-wake cycles.
Dr. Chenlu Gao, the study’s lead author and a postdoctoral research fellow at Massachusetts General Hospital in Boston, expressed her team’s surprise at the prevalence and inconsistency of napping among middle-to-older adults. She remarked, “In evaluating the sleep study results, 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.” Her observations suggest that not all naps are created equal: longer naps, irregular nap schedules, and naps timed around midday may be more problematic than short, early-afternoon power naps, at least regarding longevity.
This stands in contrast to existing guidelines from the American Academy of Sleep Medicine, which suggest that healthy adults can benefit from naps lasting 20 to 30 minutes, ideally in the early afternoon. These brief naps are thought to boost alertness and cognitive performance without the drawbacks of grogginess, or “sleep inertia,” that often accompany longer naps. However, the study’s findings indicate that naps extending beyond this optimal duration—particularly when taken later in the day or with considerable day-to-day variability—might carry unintended health consequences. This discovery challenges the notion that any daytime nap is beneficial and highlights the importance of a more nuanced approach to sleep hygiene in older populations.
What is particularly compelling about these results is their diverging from what was previously believed about midday and early afternoon naps. Dr Gao acknowledged this apparent contradiction: “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.” This discrepancy suggests that underlying physiological or behavioural factors may be at play that are not yet fully understood. For instance, the desire to nap during these periods might reflect undiagnosed health issues that contribute to increased mortality risk, or subtle circadian effects may render these nap periods more harmful than beneficial.
The methodology of the study itself was robust, encompassing 86,565 participants from the UK Biobank who were not engaged in shift work. Participants had an average baseline age of 63, and 57% were women. The researchers employed actigraphy, a method that tracks movement to infer sleep over seven days, defining daytime naps as any sleep episode between 9 a.m. and 7 p.m. Mortality data were obtained from national registries, providing a comprehensive and reliable source for long-term outcomes. During a follow-up period of up to 11 years, 5,189 participants, or 6% of the cohort, died. Notably, the analysis accounted for a range of potential confounding variables, such as demographic details, body mass index, smoking and alcohol use, and the duration of night-time sleep, all of which could have influenced the observed associations.
Dr. Gao did, however, caution that the study’s reliance on actigraphy presented some limitations. Since actigraphy measures only movement rather than brain activity, periods of quiet wakefulness may have been mistaken for sleep, leading to potential misclassification of some naps. Moreover, defining daytime napping as any sleep occurring between 9 a.m. and 7 p.m. could have inadvertently included segments of some participants’ main sleep episodes, particularly those with unconventional sleep schedules. Despite these limitations, the results offer valuable insights into how the nuanced patterns of daytime napping could significantly predict long-term health outcomes.
Ultimately, these findings underscore the importance of integrating daytime sleep patterns into broader health assessments, particularly in middle-aged and older adults. Dr. Gao suggested that incorporating such data into clinical and public health practices might offer new avenues for early risk identification and targeted interventions to support longevity. In light of these discoveries, it is becoming increasingly clear that night-time and daytime sleep behaviours deserve closer scrutiny in efforts to promote healthy ageing and reduce the burden of chronic disease. As researchers continue to explore the intricate connections between sleep and mortality, this study provides a timely and compelling impetus to consider how even small details in our daily rest routines carry weighty implications for our future well-being.
More information: Chenlu Gao et al, Objectively-Assessed Napping Behaviors Predict Mortality in Middle-to-Older Aged Adults, SLEEP. DOI: 10.1093/sleep/zsaf090.0350
Journal information: SLEEP Provided by American Academy of Sleep Medicine
