Meta-analysis: alertness improves
A systematic review and meta-analysis published in 2021 looked at the cognitive performance of working-age adults after a daytime nap. Overall performance improved in the nap group, especially alertness. The benefit appeared mainly within two hours of the nap, and early-afternoon naps gave better results.[1]
The authors note that almost all of the studies they analysed were done in a laboratory.[1]
Naps and brain volume
Researchers at University College London and the University of the Republic in Uruguay used UK Biobank data and Mendelian randomisation, a genetic method that reduces bias from lifestyle factors. Habitual daytime napping was linked to a total brain volume 15.8 cm³ larger.[2]
The researchers estimate that this difference corresponds to roughly 2.6–6.5 years of brain ageing. They found no link with hippocampal volume, reaction time or visual memory, and describe the association as modest.[2]
Bottom line
A nap won’t make anyone a genius. But a short break helps you focus for the next couple of hours, and may support brain health in the long run.
Sources
- Dutheil F, Danini B, Bagheri R et al. Effects of a short daytime nap on the cognitive performance: a systematic review and meta-analysis. International Journal of Environmental Research and Public Health. 2021;18(19):10212. doi.org/10.3390/ijerph181910212 (opens in a new window)
- Paz V, Dashti HS, Garfield V. Is there an association between daytime napping, cognitive function, and brain volume? A Mendelian randomization study in the UK Biobank. Sleep Health. 2023. doi.org/10.1016/j.sleh.2023.05.002 (opens in a new window)
