Longevity Briefs: Is Napping A Sign Of Failing Health?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

The problem:

The relationship between sleep, daytime napping and ageing is a difficult one to untangle. Are naps a normal and healthy part of ageing, or are they indicative of poorer quality sleep during the night during the night that requires compensation during the day? Studies suggest that excessive napping in later life is associated with increased risk of neurodegenerative disease and death, but this is a chicken and egg situation, as neurodegenerative diseases may contribute to sleep disruption before they are detected. In this study, researchers asked a question that has not often been considered in studies of napping: does the timing and frequency of naps influence the association between napping and mortality?

The discovery:

In order to answer this question, researchers looked at data from a study that followed 1338 people aged 56 and above from 1997 to 2025. Participants had worn a wrist actigraph, a wearable device that measures movement, for 14 days. When combined with modern algorithms, this allowed researchers to accurately determine when the participants were sleeping. They found that the duration, timing and number of naps all had an association with mortality after controlling for confounding factors. In the model with the strictest controls, they found that each 1 hour increase in nap time was associated with a 13% increase in mortality from all causes, which was roughly equivalent to the mortality risk associated with being 1.1 years older. For example, a 60 year-old who napped for 3 hours a day would have roughly the same risk of death as a 62 year-old who napped for 1 hour a day.

A similar relationship was observed for nap frequency, with each additional nap being associated with a 7% increase in mortality risk in the strictest model, roughly equivalent to being 0.6 years older in terms of risk. This could simply have been reflective of more frequent naps amounting to longer total time spent napping.

Finally, the researchers looked at the subset of participants that were frequent nappers (napped more than 15 minutes per day and on more than 2 days during the measurement period) and classified them as morning, early afternoon or late afternoon nappers based on when their 3 hour ‘peak napping window’ was. They found that with the strictest controls, there was a statistically significant association between morning napping and mortality when compared to early afternoon napping (but not late afternoon napping). Those who napped primarily in the morning had a 30% increase in all-cause mortality compared to those who napped in the early afternoon, roughly equivalent to the risk associated with being 2.5 years older. However, when the researchers broke participants down according to cognitive function, they found that this association went away in cognitively intact people.

The implications:

This research suggests that longer time spent napping is indicative of higher mortality risk. Since this study was observational in nature, it doesn’t necessarily mean that more napping causes increased mortality – rather that napping may be a compensation for other health issues. We know that poor sleep quality and quantity during the night is associated with increased mortality, but the researchers controlled for nighttime sleep patterns, meaning that napping habits were less likely to be compensating for poor sleep and more likely to be related to fatigue caused by underlying disease. Respiratory, cardiovascular, neurodegenerative disease and diabetes have all been found to be associated with increased fatigue during the day in previous studies.

So, there is nothing in this study indicating that taking a nap when you need one is harmful compared to resisting the urge to nap, but long or frequent naps, especially if they occur in the morning, could be a sign of disease. Also, given that most participants were white Americans, it is unlikely that many of the naps taking place were planned naps such as siestas, but rather naps of necessity brought on by fatigue. A study in a culture for which napping is a more common element of one’s daily routine might yield different results.