Daytime Napping May Combat Brain Shrinkage

Adults who partake in short daytime naps could be doing more than catching up on sleep. New research suggests they could also be slowing the rate at which the brain shrinks with age. Researchers at University College London and Uruguay's University of the Republic took data from 35,080 people, aged 40 to 69, collected through the UK Biobank project, per the Guardian. They then keyed in on those with genetic variants previously associated with self-reported habitual daytime napping—an approach that "avoids confounding factors ... that may influence associations between napping and health outcomes," lead author Valentina Paz, a PhD candidate at University of the Republic, tells the Independent.

"We found an association between habitual daytime napping and larger total brain volume, which could suggest that napping regularly provides some protection against neurodegeneration through compensating for poor sleep," the researchers write in the journal Sleep Health, per the Guardian. The brains of those with the genetic predisposition to habitual daytime napping were about 0.9 cubic inches larger than those of the genetic non-nappers, which researchers said was equivalent to 2.6 to 6.5 fewer years of aging. "It could be having a short daytime nap … could help preserve brain volume and that's a positive thing, potentially, [for] dementia prevention," says study co-author Dr. Victoria Garfield of UCL, per the Guardian.

"We are suggesting that everybody could potentially experience some benefit from napping," Garfield adds, per the BBC. However, it's not clear if the same benefits would apply to daytime nappers without the genetic predisposition, which only about 1% of people have, the Guardian reports. Across the sample size, participants who reported never or rarely having a daytime nap actually had a larger total brain volume than those who reported sometimes or usually having a daytime nap, though those in the latter group were more likely to smoke and suffer from diabetes and cardiovascular disease. The approach also failed to show what duration of nap was beneficial, though previous research suggests under 30 minutes is best. (More napping stories.)