Habitually Taking Daytime Naps Associated with Larger Total Brain Volume

According to research published in Sleep Health, people who habitually took daytime naps had brains that were larger by a volume equivalent to 2.6 to 6.5 years of aging compared to people who didn’t nap. The findings suggest that daytime napping may play a role in delaying the process of brain shrinking that occurs with age.

The study genotyped 487,409 participants from the UK Biobank (UKB) cohort, then excluded participants based on quality-controlled genotype and phenotype data and ancestry, narrowing to a sample size of 378,932 participants aged 40-69 years with European ancestry. Primary outcomes of the study were cognitive function, as measured by visual memory and reaction time tests, and hippocampal and total brain volume, as measured by magnetic resonance imaging (MRI). Researchers instrumented daytime napping using 123 genome-wide genetic variants which were identified by participants’ answers to the question, “Do you have a nap during the day?” Associations between genome variants and primary outcomes were evaluated by linear regression performed with PLINK 2.0. Larger total brain volumes were associated with the analyzed genetic instrument and self-reported napping behavior, with no relationships identified for cognitive function and hippocampal volume.

“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 study author Dr Victoria Garfield. “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.”

The study was conducted by researchers at University College London. A potential direction for future investigations is whether habitual daytime napping has any role in preventing neurodegenerative conditions such as Alzheimer disease.