Researchers at University College London and Massachusetts General Hospital tested that assumption using genetic data from more than 378,000 adults in the UK Biobank, using variants linked to habitual daytime napping as a proxy for the habit itself.
People with a stronger genetic tendency to nap had measurably larger total brain volume, a difference the team calculated as equivalent to between two and a half and six and a half years of typical age-related brain shrinkage. Hippocampal volume, reaction time and visual memory showed no such link.
Mendelian randomization cannot prove napping itself caused the difference, only that the genetic tendency to nap moves alongside it, and it cannot rule out other causes of daytime sleepiness, like undiagnosed sleep apnea. The method sidesteps the usual confound that unwell people nap more, since it starts from genes fixed at birth rather than habits adopted later.
Read the original study
Paz et al., Sleep Health, 2023 · doi.org/10.1016/j.sleh.2023.05.002
A nap, written into the genes.
Source
- Paz, V., Dashti, H. S., & Garfield, V. (2023). Is there an association between daytime napping, cognitive function, and brain volume? A Mendelian randomization study in the UK Biobank. Sleep Health, 9(5), 786–793. https://doi.org/10.1016/j.sleh.2023.05.002