Brief naps during the day may help protect brain health as we age, researchers suggest after finding the practice appears to be associated with larger brain volume.
While previous research has suggested that long naps may be an early symptom of Alzheimer’s disease, other work has shown that short naps can improve people’s ability to learn.
Now researchers say they’ve found evidence that napping may help protect against brain shrinkage.
That’s of interest, the team says, because brain shrinkage, a process that occurs with age, is accelerated in people with cognitive problems and neurodegenerative diseases, with some research suggesting it may be linked to sleep problems.
“Consistent with these studies, we found an association between habitual daytime naps and larger total brain volume, which may suggest that regular napping offers some protection against neurodegeneration by compensating for poor sleep,” the researchers note.
Researchers from UCL and the University of the Republic of Uruguay report in the journal Sleep Health how they drew on data from the UK Biobank study, which collected genetic, lifestyle and health information from 500,000 people aged 40 to 69 at recruitment were collected.
The team used data from 35,080 biobank participants to examine whether a combination of genetic variants previously associated with self-reported habitual daytime napping are also associated with brain volume, cognition, and other aspects of brain health.
Given that such variants are established at birth and are assumed to be assigned randomly, this approach allows researchers to study the effects of napping on the brain by reducing the impact of lifestyle factors affecting napping habits and napping habits can affect brain health in humans, such as B. Smoking or smoking physical activity.
“It’s like a natural randomized control study,” said Dr. Victoria Garfield, co-author of the study from University College London, added that the variants are quite common. “They’re found in at least 1% of the population, which is actually quite a lot of people.”
While it initially appeared that participants who reported never or rarely napping during the day had greater total brain volume, when genetic predisposition to napping was taken into account, the team found the opposite association, suggesting that the original finding could be due to other factors skewing the results of the relationship between daytime sleep and brain size.
Overall, the team found an association between being genetically predisposed to habitual daytime naps and larger brain volume, equivalent to aging by 2.6 to 6.5 years, although there was no association with cognitive performance such as reaction times.
“It might be that taking short naps during the day… might help maintain brain volume, and that’s potentially a positive thing.” [for] Dementia prevention,” Garfield said, adding that previous research suggested that durations of up to 30 minutes could be beneficial.
Garfield noted that there are a variety of risk factors that could lead to dementia, while many other factors could also affect brain volume.
Additionally, the study is only based on data from white Britons and the exact length of naps associated with the benefits is unclear. It’s also unclear whether the same benefits of napping would occur in non-predisposed people.
Prof Tara Spiers-Jones, President of the British Neuroscience Association, Group Leader at the UK Dementia Research Institute and Associate Director of the Center for Discovery Brain Sciences at the University of Edinburgh, welcomed the study, although she said it had limitations, including that the self-reported napping habits of UK Biobank participants may not be entirely accurate.
“This study is important because it adds to the data showing that sleep is important for brain health,” she said.