Today in unsettling news: Results published in a recent issue of the American Journal of Epidemiology suggest a correlation between daytime napping and increased mortality risk.
Photo Credit: Ernesto De Quesada // CC BY 2.0
The study, led by University of Cambridge epidemiologist Yue Leng, looked at the associations between daytime napping and mortality in a survey of over 16,000 British men and women. Their findings suggest that daytime nappers are nearly a third more likely to die before they turn 65 (even after they accounted for things like sex, social class, smoking status, and more). Here's the abstract:
Among the 16,374 men and women who answered questions on napping habits between 1998 and 2000, a total of 3,251 died during the 13-year follow-up. Daytime napping was associated with an increased risk of all-cause mortality (for napping less than 1 hour per day on average, hazard ratio = 1.14, 95% confidence interval: 1.02, 1.27; for napping 1 hour or longer per day on average, hazard ratio = 1.32, 95% confidence interval: 1.04, 1.68), independent of age, sex, social class, educational level, marital status, employment status, body mass index, physical activity level, smoking status, alcohol intake, depression, self-reported general health, use of hypnotic drugs or other medications, time spent in bed at night, and presence of preexisting health conditions. This association was more pronounced for death from respiratory diseases (for napping less than 1 hour, hazard ratio = 1.40, 95% confidence interval: 0.95, 2.05; for napping 1 hour or more, hazard ratio = 2.56, 95% confidence interval: 1.34, 4.86) and in individuals 65 years of age or younger. Excessive daytime napping might be a useful marker of underlying health risk, particularly of respiratory problems, especially among those 65 years of age or younger.
It bears mentioning that we're talking about correlation here, not causation, so saying that "taking a nap will knock years off your life" is a bit dishonest, to say the least. Still, if you find yourself consistently dozing off in the daytime, there's reason to believe it could be linked to an underlying health issue. Leng and the other authors of the present study note that "the exact mechanisms of these associations remain unknown," but previous investigations into the link between napping and increased mortality have found daytime sleepiness to be associated with poor sleep hygiene, which itself is linked to a whole slew of other problems cardiovascular, respiratory and metabolic in nature.
The full results of the present study can be accessed in their entirety, free of charge, at the American Journal of Epidemiology.