A significant new study has revealed that daytime napping may be associated with a higher risk of premature death. Conducted by researchers who monitored the sleep habits of over 86,000 healthy middle-aged adults, the findings indicate that individuals who regularly nap, particularly in the early afternoon, face a greater likelihood of dying earlier than those who do not nap. This research was presented at the SLEEP 2025 conference and highlights critical insights into the implications of daytime sleep.
The study discovered that the risk of death among frequent nappers increased by as much as 20%. Experts suggest that excessive daytime sleepiness may signal disrupted or poor-quality night-time sleep and could indicate underlying health issues, including sleep disorders, dementia, or heart failure. Professor James Rowley from Rush University Medical Center emphasized the importance of this finding, stating that healthcare providers should inquire about patients' napping habits in addition to their overall sleep patterns.
The study specifically focused on middle-aged adults who did not work night shifts and had no significant health issues at the beginning of the research. This approach helped eliminate other factors that could contribute to excessive daytime sleepiness, suggesting that the connection between napping and early death is not merely due to existing health problems or lifestyle choices. Participants' sleep was monitored over a week using actigraphy, which involves a small, watch-like device that tracks sleep-wake patterns.
Daytime napping was defined as any sleep occurring between 9 AM and 7 PM. On average, participants napped for approximately 24 minutes, with about one-third of these naps occurring in the morning, specifically between 9 AM and 11 AM. Over an 11-year follow-up period, 5,189 participants died. The study noted that as participants aged, their daytime sleep duration increased. After accounting for various lifestyle factors such as smoking, alcohol consumption, and nighttime sleep duration, the results demonstrated that inconsistent napping patterns correlated with a 14% increased risk of mortality.
Lead researcher Professor Chenlu Gao from Harvard Medical School explained that the study fills a critical gap in understanding the relationship between napping and health. He emphasized that it's not just about whether someone naps, but also the duration, variability, and timing of naps that may serve as significant indicators of future health risks. While previous studies have mainly focused on nighttime sleep, Gao pointed out that napping is an essential aspect of the 24-hour sleep-wake cycle and could have distinct health implications.
The researchers urged for additional studies to explore the biological mechanisms behind these associations. They noted that longer or more irregular naps might reflect underlying health conditions such as heart disease, type 2 diabetes, depression, and dementia. Other research has suggested that disruptions to our circadian rhythms—the natural cycles that regulate various bodily functions—could play a role in this relationship. Experts from the Karolinska Institute in Stockholm also proposed that daytime sleep could hinder the brain's ability to eliminate waste accumulated during wakefulness.
This study's findings align with previous research indicating that nearly half of all Alzheimer's disease cases—one of the leading causes of dementia—could be prevented by addressing 14 lifestyle factors, such as hearing loss, high cholesterol, vision loss, and lack of exercise. Published in the prestigious journal The Lancet, this study provided renewed hope for preventing this debilitating disorder. In the UK alone, Alzheimer’s disease affects approximately 982,000 individuals, with dementia being the leading cause of death, accounting for 74,261 fatalities in 2022.
Moreover, a 2019 estimate indicated that the annual death toll from dementia-related health issues stands at around 70,000, costing the NHS approximately £700 million annually. The World Health Organization reports that physical inactivity contributes to around 2 million deaths each year globally, positioning it among the top 10 leading causes of death and disability worldwide.
