If you’ve ever felt guilty for indulging in an afternoon nap, you’re not alone. While millions of people around the world routinely enjoy a midday snooze, the long-term effects of napping on brain health have remained unclear. However, recent research is offering fresh insights into whether short bouts of daytime rest might actually benefit the aging brain.
Investigating the Link Between Napping and Brain Size
A collaborative study conducted by researchers from University College London, the University of the Republic in Uruguay, and the Broad Institute in Massachusetts explored whether habitual napping might play a role in preserving brain health. Specifically, they investigated whether a genetic tendency to nap is associated with larger brain volume, a marker commonly linked to better neurological function.
Using data from nearly 379,000 participants in the UK Biobank, aged 40 to 69, the researchers focused on 92 genetic markers previously tied to frequent napping. They then compared these markers with brain scans and cognitive test results, including measurements of total brain volume, hippocampal volume, reaction time, and visual memory.
Mendelian Randomization: A Genetic Approach
To determine whether the connection between napping and brain health was causal rather than coincidental, the researchers used a method called Mendelian randomization. This approach analyzes genetic variations that are set at birth to help eliminate external factors like lifestyle or environment, which often complicate traditional observational studies.
By focusing on inherited genetic traits, the team hoped to determine whether the tendency to nap could directly influence brain size, rather than simply being associated with it.
Key Findings from the Study
The results showed a modest but meaningful connection: individuals genetically inclined to nap had slightly larger brain volumes.
The difference was around 15.8 cubic centimeters—the equivalent of postponing age-related brain shrinkage by approximately 2.5 to 6.5 years. Since brain shrinkage is often linked with cognitive decline and neurodegeneration, this suggests that napping could play a role in maintaining brain structure over time.
However, the study didn’t find any significant association between the genetic markers and other brain functions such as memory, reaction time, or hippocampal size.
So, while habitual nappers may have slightly larger brains, this didn’t necessarily translate into sharper mental performance based on the metrics used.
Cultural Norms and Conflicting Evidence
Napping is common in many cultures, from Mediterranean siestas to afternoon breaks in parts of Asia.
Previous studies have found that short naps can enhance alertness and cognitive function in the short term. But when it comes to long-term brain health, the evidence has been mixed.
Some research links frequent napping to increased risk of neurological disorders, while other studies suggest the opposite.
This recent research aims to clarify that debate by examining the genetic influence on napping and its possible connection to brain health.
Interpreting the Results with Caution
Although Mendelian randomization offers a more reliable way to explore cause and effect, it doesn’t provide definitive proof. The study did not track actual nap behavior—only genetic predisposition—so it’s unclear how nap duration, frequency, or quality might impact brain health.
The study also relied on broad, self-reported categories like “never,” “sometimes,” or “usually” for napping frequency, which leaves room for subjective interpretation. Moreover, the sample group was not highly diverse, and overlapping data sets may have introduced subtle biases.
Why Might Napping Be Helpful?
The study didn’t explore how naps might support brain health, but other research suggests sleep helps clear toxins from the brain and supports neural maintenance.
If naps include deep, slow-wave sleep, they might help preserve brain volume by promoting restorative processes. Some speculate that dreaming and REM sleep may also contribute to mental rejuvenation.
Final Thoughts: To Nap or Not to Nap?
While the findings don’t prove that naps make you smarter or improve memory, they do suggest that daytime rest could play a small but meaningful role in preserving brain structure as we age. Still, experts warn against overreliance on naps, as excessive daytime sleep can disrupt nighttime rest.
Ultimately, maintaining a healthy sleep schedule over a full 24-hour period remains key. Napping, when done in moderation, might be a helpful addition, not a substitute, for good sleep hygiene.
