Link Found Between Daytime Napping and Brain Health

Link Found Between Daytime Napping and Brain Health

John Patterson – In our fast-paced world, napping during the day often carries a negative stigma. Many perceive it as a sign of laziness or lack of productivity. However, a groundbreaking study led by researchers at UCL and the University of the Republic in Uruguay challenges these misconceptions.

The study, published in the prestigious journal Sleep Health, reveals a fascinating connection between daytime napping and the preservation of brain health as we age. These findings offer valuable insights into the potential benefits of incorporating short naps into our daily routines.

A Puzzle Piece for Brain Health

The study examined data from individuals aged 40 to 69 and identified a causal relationship between habitual napping and larger total brain volume. Total brain volume serves as an essential marker of good brain health, associated with a decreased risk of dementia and other cognitive diseases.

Dr. Victoria Garfield, senior author from the MRC Unit for Lifelong Health & Ageing at UCL, explains that “short daytime naps may be a part of the puzzle that could help preserve the health of the brain as we get older.”

Previous research has already demonstrated the cognitive benefits of napping, with individuals who engage in short naps performing better in cognitive tests than their non-napping counterparts. This new study aimed to establish a causal link between daytime napping and brain health to provide a deeper understanding of the relationship.

Mendelian Randomization Unveils Insights

To investigate this connection, researchers utilized a technique called Mendelian randomization. They examined 97 snippets of DNA associated with the likelihood of habitual napping. By comparing brain health and cognition measures of individuals genetically predisposed to napping with those lacking these genetic variants, the study analyzed data from 378,932 participants from the UK Biobank study.

The findings revealed that people genetically inclined to nap exhibited larger total brain volumes.

The research team estimated that the average difference in brain volume between habitual nappers and non-nappers was equivalent to a difference of 2.6 to 6.5 years of aging. However, no significant differences were found in other measures of brain health and cognitive function, such as hippocampal volume, reaction time, and visual processing, among those predisposed to napping.

Valentina Paz, the lead author and PhD candidate from the University of the Republic (Uruguay) and MRC Unit for Lifelong Health & Ageing at UCL, highlights the significance of their study, stating that it is the first to explore the causal relationship between daytime napping and cognitive and structural brain outcomes.

By relying on genetic factors established at birth, Mendelian randomization helps eliminate confounding variables that may influence the associations between napping and health outcomes. Ultimately, this study confirms a causal link between habitual napping and larger total brain volume.

Diminishing Stigma and Promoting Awareness

Dr. Garfield expresses hope that studies like this one, showcasing the health benefits of short naps, can help eradicate the stigma surrounding daytime napping. Napping, when incorporated responsibly into our routines, may prove to be a valuable tool in maintaining brain health and overall well-being.

The Genetic Connection

The genetic variants influencing an individual’s likelihood to nap were identified in a previous study analyzing data from 452,633 UK Biobank participants. Dr. Hassan Dashti, from Harvard University and Massachusetts General Hospital, led the study, which identified the variants based on self-reported napping, supported by objective measurements of physical activity recorded by a wrist-worn accelerometer.

In the current study, researchers examined health and cognition outcomes for individuals possessing these genetic variants, alongside various subsets of these variants, while adjusting for potential biases. Magnetic resonance imaging (MRI) scans of the brain and genetic data were available for 35,080 individuals drawn from the larger UK Biobank sample.

Considerations and Future Research

Although this study presents compelling evidence, it is crucial to acknowledge certain limitations. The participants in the study were predominantly of white European ancestry, and further research is necessary to ascertain the generalizability of these findings to other ethnicities.

While the study did not account for nap duration, earlier research suggests that naps lasting 30 minutes or less offer the best short-term cognitive benefits. Furthermore, napping earlier in the day is less likely to disrupt nighttime sleep.


This ground breaking study sheds light on the surprising connection between daytime napping and brain health preservation. By establishing a causal link between habitual napping and larger total brain volume, it challenges the negative perceptions associated with napping and highlights its potential benefits.

As we strive to maintain cognitive well-being as we age, short daytime naps could be an integral part of the puzzle. Let us embrace this knowledge and consider incorporating short, restorative naps into our daily routines to safeguard the health of our brains in the long run.


Valentina Paz, Hassan S. Dashti, Victoria Garfield. Is there an association between daytime napping, cognitive function, and brain volume? A Mendelian randomization study in the UK Biobank. Sleep Health, 2023;

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