Regular Day Time Napping Could Help Preserve the Health of the Brain

Researchers have found that daytime napping could help in preserving the health of the brain by slowing down the rate at which the brain shrinks as we grow older.¹✅ JOURNAL REFERENCE
DOI: 10.1016/j.sleh.2023.05.002

Data were analyzed from individuals between the ages of 40 and 69 and observed a causal association between regular napping and greater total brain volume, which is an indication of healthy brain function associated with a reduced risk of dementia as well as other conditions.

The results indicate that, for some individuals, short naps in the daytime could help in preserving brain health as we age.

Prior studies have demonstrated the cognitive benefits that napping has, with individuals who’ve had a short nap outperforming those who didn’t nap in cognitive testing in the hours after napping.

The goal of the current study was to determine if there was a causal association between napping in the daytime and the health of the brain.

Making use of a method known as Mendelian randomization, 97 DNA snippets were looked at which are believed to determine the likelihood of a person’s habitual napping. Cognition and brain health measures of individuals more genetically predetermined to nap were compared with individuals without these genetic variants, making use of information from 378,932 individuals who took part in the UK Biobank study, and it was generally observed that individuals programmed to nap had a greater total brain volume.

The average brain volume difference between individuals predetermined to be regular nappers and individuals who weren’t was estimated to be equal to 2.6 to 6.5 years of aging.

A difference was however not observed in how well individuals predetermined to be regular nappers performed on 3 other cognitive function and brain health measures, namely visual processing, reaction time, and hippocampal volume.

This study attempted to unravel the causal association between regular daytime napping and structural and cognitive brain outcomes. Mendelian randomization takes a look at genes determined at birth which reduces the risk of confounding factors happening during life that could influence links between daytime napping and health outcomes.

The study suggests a causal association between regular napping and greater total brain volume.

The genetic variants having an influence on the likelihood of napping were established in a previous study that looked at data from 452,633 individuals who participated in the UK Biobank study. The variants were identified based on self-reported napping backed up by objective physical activity measurements recorded by an accelerometer worn on the wrist.

In the current study, cognition and health outcomes for individuals having these genetic variants were analyzed in addition to a number of different variant subsets, adjusted for avoiding potential bias, for example avoiding variants associated with excessive daytime sleepiness.

MRI brain scans and genetic data were accessible for 35,080 people taken from the larger sample of the UK Biobank study.

In regards to the limitations of the study, all of the individuals were white Europeans, so the results may not apply to other ethnicities.

Although the researchers didn’t have data on the duration of naps, earlier research suggests that naps of half an hour or less offer the optimal cognitive benefits, and naps taken earlier in the day are unlikely to disrupt sleep at night.