Stress hormones
In a laboratory experiment in Paris, healthy men were limited to two hours of sleep for one night. The next day, their level of norepinephrine, a hormone involved in the stress response, rose 2.5-fold. When participants were allowed to nap after such a night, this rise did not occur, and their level of interleukin-6, a protein linked to the immune system, stayed normal.[1] The authors concluded that napping has stress-relieving and immune-supporting effects.[1]
The heart: occasional naps
The Swiss CoLaus cohort study followed 3,462 adults for an average of five years. People who napped once or twice a week had a 48% lower risk of cardiovascular events than people who didn’t nap. No link was found for more frequent napping or for nap length.[2] This is an observational study: it shows an association, not a cause.
A warning: long daily naps
A meta-analysis by Japanese researchers found a J-shaped relationship. Daily naps of 60 minutes or more were linked to an 82% higher risk of cardiovascular disease and 27% higher all-cause mortality. Naps under 60 minutes showed no link with heart disease.[3]
Long daily daytime sleep can be a sign of poor night-time sleep or an underlying health problem. If you need a long nap every day, talk to your doctor.
Conclusion
A short, planned nap is the best-supported option. Long daily daytime sleep isn’t a tool; it’s a signal.
Sources
- Faraut B et al. Napping reverses the salivary interleukin-6 and urinary norepinephrine changes induced by sleep restriction. Journal of Clinical Endocrinology & Metabolism. 2015;100(3):E416–E426. doi.org/10.1210/jc.2014-2566 (opens in a new window)
- Häusler N, Haba-Rubio J, Heinzer R, Marques-Vidal P. Association of napping with incident cardiovascular events in a prospective cohort study. Heart. 2019. doi.org/10.1136/heartjnl-2019-314999 (opens in a new window)
- Yamada T, Hara K, Shojima N, Yamauchi T, Kadowaki T. Daytime napping and the risk of cardiovascular disease and all-cause mortality: a prospective study and dose-response meta-analysis. Sleep. 2015;38(12):1945–1953. pmc.ncbi.nlm.nih.gov/articles/PMC4667384 (opens in a new window)
