It is common for young children to take a nap, but there are also many adults who are not willing to give up this good habit, and some studies prove them right, since they have shown that after enjoying one of these brief periods of daytime sleep people do better on cognitive tests taken in the hours afterward than those who haven’t had a nap. Now, a new study that aimed to determine if there is a causal relationship between daytime naps and brain health has concluded that taking naps during the day may help protect brain health.
The study was carried out by researchers from University College London (UCL) and the University of the Republic in Uruguay, who analyzed data from individuals aged 40 to 69 and found a causal link between regular naps and a largest total brain volumea marker of good brain health related to a lower risk of dementia and other diseases. The results have been published in Sleep Health.
“Our findings suggest that, for some people, the short naps during the day may be part of the puzzle that could help preserve brain health as we age,” said lead author Dr. Dra. Victoria Garfield from the MRC Unit for Lifelong Aging and Health at UCL.
Genetic Variants Influence Siesta Preference
The researchers used a technique called Mendelian randomization to look at 97 pieces of DNA thought to determine how likely people are to nap regularly. They used data from 378,932 people from the UK Biobank study to compare measures of brain health and cognition of individuals more genetically ‘programmed’ to nap with others who lacked these genetic variants, and found that, in general, people predetermined to nap had a larger total brain volume.
These scientists estimated that the average difference in brain volume between people who were ‘programmed’ to take regular naps and those who were not was equivalent to between 2.6 and 6.5 years of aging. However, they found no differences in three other measures of brain health and cognitive function — hippocampal volume, reaction time, and visual processing — in those scheduled to nap regularly.
Naps lasting 30 minutes or less provide the greatest short-term cognitive benefits
The genetic variants that influence our likelihood of napping were identified in an earlier study that analyzed data from 452,633 participants from the UK Biobank, led by the Dr. Hassan Dashti (Harvard University and Massachusetts General Hospital), who is also an author on the new study. Variants were identified on the basis of self-reported napping, supported by objective measurements of physical activity recorded by a wrist accelerometer.
The authors of the new study looked at the health and cognition outcomes of individuals with these gene variants, as well as several different subsets of these variants, adjusted for potential bias, for example, avoiding variants linked to the excessive daytime sleepinessand for this they had the genetic data and magnetic resonance images of the brain of 35,080 individuals from the United Kingdom Biobank.
Although they did not know the duration of the nap in previous studies it has been suggested that the naps that last 30 minutes or less they are the ones that provide the greatest short-term cognitive benefits and are least likely to interfere with nighttime sleep. “This is the first study to attempt to tease out the causal relationship between habitual daytime napping and cognitive and structural brain outcomes. By looking at genes established at birth, Mendelian randomization avoids confounding factors that occur throughout life and that can influence associations between napping and health outcomes. Our study points to a causal link between habitual naps and a larger total brain volume,” explained lead author and PhD candidate Valentina Paz (Universidad de la República (Uruguay) and MRC Unit for Health and Aging from Por Life at UCL.
The teacher Tara Spires-Jonespresident of the British Neuroscience Association, group leader at the UK Dementia Research Institute and deputy director of the Center for Brain Science Discovery at the University of Edinburgh, believes the study “is interesting because it adds to the data indicating that the sleep is important for brain health”, although he acknowledges some limitations, as he has detailed in statements to foreignaffairs.co.nz: “While this is a well-conducted study, it does have limitations. Mendelian randomization aims to establish whether napping caused the observed changes in brain volume, rather than other lifestyle factors that may be associated with napping, by using a genetic signature. This is stronger at establishing causation than studies looking at napping behavior (rather than genetics), but that depends on the precision of the signature. The UK Biobank participants’ napping habits were self-reported, which might not be entirely accurate, and the ‘nap’ signature substantially overlapped with the signature of cognitive outcomes in the study, weakening the causal link.” .
Source: www.webconsultas.com
