June 20, 2023

expert reaction to study suggesting an association between regular napping and larger brain volume

A study published in Sleep Health looks at daytime napping, cognitive function and brain volume.

Prof Tara Spires-Jones, President of the British Neuroscience Association, Group leader at the UK Dementia Research Institute, and Deputy Director of the Centre for Discovery Brain Sciences at the University of Edinburgh, said:

“This paper by Paz, Dashti, and Garfield shows a small but significant increase in brain volume in people who have a genetic signature associated with taking daytime naps. Scientists studied participants in the large UK Biobank cohort using a method called Mendelian Randomization that used the fingerprint of genes associated with napping to try and determine whether napping causes changes in the brain.  While this is a well-conducted study, it does have limitations. Mendelian randomization is intended to establish whether napping caused the observed changes in brain volume, instead of other lifestyle factors which may be associated with napping, by using a genetic signature.  This is stronger for establishing causation that studies that look at napping behaviour (instead of the genetics) but that depends on the accuracy of the signature.  The napping habits of UK Biobank participants were self-reported, which might not be entirely accurate, and the “napping” signature overlapped substantially with the signature for cognitive outcomes in the study, which makes the causal link weaker.  Even with those limitations, this study is interesting because it adds to the data indicating that sleep is important for brain health.”

‘Is there an association between daytime napping, cognitive function and brain volume? A Mendelian randomisation study in the UK Biobank’ by Valentina Paz et al. was published in Sleep Health at 00:01 UK Time Tuesday 20 June 2023.

DOI: 10.1016/j.sleh.2023.05.002

Declared interests

Prof Tara Spires-Jones: I have no conflicts with the study.