Research suggests that taking regular daytime naps could be good for brain health.
A study led by researchers at University College London and the University of the Republic in Uruguay found a correlation between daytime napping and the rate at which brains shrink as they age.
The study suggests the average difference in brain volume between people programmed to be habitual nappers and those who were not was equivalent to 2.6 to 6.5 years of ageing.
“Our findings suggest that, for some people, short daytime naps may be a part of the puzzle that could help preserve the health of the brain as we get older,” said senior author Victoria Garfield, MRC Unit for Lifelong Health & Ageing at UCL.
The study, published in the journal Sleep Health, analysed data from people aged 40 to 69.
Past research has suggested people who have had a short nap perform better in cognitive tests in the hours afterwards than those who did not nap.
The new study looked at whether there was a causal relationship between daytime napping and brain health.
Researchers looked at 97 snippets of DNA thought to determine people’s likelihood of habitual napping.
They compared measures of brain health and cognition of people who are more genetically programmed to nap with people who did not have these changes in DNA, using data from 378,932 people in the UK Biobank study.
They found that, overall, people predetermined to nap had a larger total brain volume.
The genetic variants – DNA changes – influencing the likelihood of someone to nap were identified in an earlier study looking at data from 452,633 UK Biobank participants.
But the researchers did not find a difference in how well those programmed to be habitual nappers performed on three other measures of brain health and cognitive function.
“This is the first study to attempt to untangle the causal relationship between habitual daytime napping and cognitive and structural brain outcomes,” said lead author and doctoral candidate Valentina Paz, University of the Republic and MRC Unit for Lifelong Health & Ageing at UCL.
“By looking at genes set at birth, Mendelian randomisation avoids confounding factors occurring throughout life that may influence associations between napping and health outcomes.”
Dr Garfield added: “I hope studies such as this one showing the health benefits of short naps can help to reduce any stigma that still exists around daytime napping.”
