Harvard scientists have revealed that taking naps between 9 am and 7 pm can raise the risk of early death by 13% for each additional hour of napping per day, and by 7% for each extra nap.. The study, which followed 1,400 adults aged 56 and older for up to two decades, found that 926 participants—about two‑thirds—died during the period. Morning naps were singled out as especially concerning, suggesting sleepiness when people are expected to be most alert.

Harvard’s 20‑Year Cohort Shows 13% Rise in Mortality per Nap Hour

According to the study, each extra hour of napping between 9 am and 7 pm was associated with a 13% increase in the risk of death. The researchers tracked participants’ sleep patterns and health outcomes over a 20‑year period, providing a robust longitudinal dataset. The finding underscores that daytime sleep, particularly in the late‑morning to early‑afternoon window, may be a red flag for underlying health issues.

Morning Naps Signal Hidden Health Risks, Not Sleep Quality Alone

The authors note that napping itself is unlikely to cause death; rather, it may indicate a disrupted sleep architecture linked to chronic conditions.. Morning naps, in particular,were linked to a higher risk, perhaps because they reflect sleepiness when alertness is required. The study cites prior research showing that disrupted sleep can lead to inflammation, weight gain, and chronic diseases such as heart disease and neurodegeneration.

Two‑Thirds of Participants Died , Yet Napping Was Not the Direct Cause

Of the 1,400 adults studied, 926—about two‑thirds—died over the follow‑up period. While the study could not prove causation, it suggests that daytime napping may serve as an independent marker for mortality risk. The researchers emphasizze that the timing and frequency of naps could help clinicians identify patients at higher risk of early death.

Observational Study Limits Causal Claims, Calls for Further Research

The Harvard team acknowledges that the observational nature of the study prevents definitive proof that napping raises death risk. Nonetheless, the findings highlight the importance of considering nap timing and frequency in health assessments. Future research will need to disentangle whether napping is a symptom of underlying disease or a contributing factor to mortality.