Data from nearly 400,000 people show that regular naps can increase brain capacity, but the duration should not exceed this

As we age, our brain changes and the number of neurons and connections in our brain gradually decreases, causing brain shrinkage. This can lead to cognitive decline, such as problems with memory and concentration. However, some studies have shown that lifestyle factors have a significant impact on cognitive function, such as exercise, sleep, etc., and can slow down this shrinkage.

Naps are considered an integral part of a healthy lifestyle. In recent years, people have paid more and more attention to naps, but whether naps are good for the brain remains controversial.

Recently, researchers from the University of the Republic of Uruguay, University of London, and Harvard Medical School in the United States published a research paper titled "Is there an association between daytime napping, cognitive function, and brain volume? A Mendelian randomization study in the UK Biobank" in the journal "Sleep Health".

The study showed a causal link between people who take regular naps and larger total brain volume, and that naps slow the rate at which the brain shrinks with age, helping to keep the brain healthy.

In this study, researchers analyzed 378,932 participants in the UK Biobank database with an average age of 57. Through Mendelian randomization, the researchers analyzed 92 genetic variants related to naps and compared the total brain volume, hippocampal volume, reaction time and visual memory of people with and without the nap gene.

Overall, 57% of participants reported never taking naps, 38% reported taking naps occasionally, and 5% reported taking naps frequently.

The analysis showed that people with a genetic tendency to nap were associated with a 15.8 cubic centimeters larger total brain volume compared to those without a genetic tendency to nap.

The researchers estimate that this is equivalent to slowing down brain volume aging by 2.6-6.5 years for people who have the habit of taking naps.

Association between napping and total brain volume

However, the study did not find any differences in hippocampal volume, reaction time, or performance in visual processing.

The results suggest a causal relationship between napping habits and larger total brain volume, which helps protect brain health, the researchers said. This is the first study to attempt to disentangle the causal relationship between napping habits and cognitive and structural brain outcomes.

So, how long is the most beneficial nap?

On April 26, 2023, researchers from Brigham and Women's Hospital in the United States and the University of Murcia in Spain published a research paper titled "Lifestyle mediators of associations among siestas, obesity, and metabolic health" in the journal "Obesity".

Studies have shown that the optimal nap duration is 30 minutes. Compared with those who do not take naps, those who take naps for more than 30 minutes are associated with a 41% increase in the risk of high BMI and metabolic syndrome, especially in terms of waist circumference, fasting blood sugar and blood pressure. However, those who take naps for less than 30 minutes have no metabolic health risks and perform better in terms of blood pressure.

On April 13, 2023, researchers from the University of Huelva in Spain published a study at the annual congress of the European Society of Cardiology.
Research shows that the optimal nap time is 15-30 minutes. If you nap for more than 30 minutes, your risk of arrhythmia increases by 90%, nearly doubling. Compared with people who nap for a long time, people who nap for less than 15 minutes have a 42% lower risk of atrial fibrillation, and those who nap for 15-30 minutes have a 56% lower risk of atrial fibrillation.

On April 5, 2023, researchers from the National University of Ireland published a research paper titled "Sleep Patterns and the Risk of Acute Stroke: Results from the INTERSTROKE International Case-Control Study" in the journal Neurology.

The study found that compared with no nap, napping for more than one hour was associated with a 1.88 times higher risk of stroke. Compared with 7 hours of sleep, sleeping less than 5 hours was associated with a 3.15 times higher risk of stroke, and sleeping more than 9 hours was associated with a 2.67 times higher risk of stroke.

Paper link:

https://doi.org/10.1016/j.sleh.2023.05.002

https://doi.org/10.1002/oby.23765

Long daytime naps might raise your odds for A-fib

https://doi.org/10.1212/WNL.0000000000207249