Can naps keep our brains healthy?

While longer naps could be an early symptom of Alzheimer's disease, shorter naps are more and more being associated with larger total brain volume. This means that those daytime winks you love so much may actually protect against brain shrinkage as you age.

Brain shrinkage is a process that is accelerated with age, and can be found in people with cognitive problems and neurodegenerative diseases. Among plenty of other causes behind brain deterioration, there is some research to suggest that sleep deprivation shares part of the blame.

Researchers from the UCL and the University of the Republic of Uruguay looked at a large database from the UK Biobank, extracting data such as their unique genetic variants, health and lifestyle habits from more than 35,000 participants. Since genetic makeup is randomly assigned and set at birth, it was easier for researchers to check if reducing the impacts of lifestyle habits such as smoking or physical activity had any impact on the fitness of health. They overall checked whether their daytime snoozing habits had any effect on brain volume, cognitive ability and other aspects of brain health, whatsoever.

At first, it was found that those that did not take daytime naps had a larger total brain volume. However, upon a closer look at whether these people were genetically predisposed to napping, it was seen that there were a wide range of other factors muddying the correlation up. In fact, a reverse correlation was then observed, and it was found that those who were genetically more inclined to take daytime naps had better brain volume even as they aged. Their brain volume was similar to the brain of a 2.5 to 6.5-year younger person.

This research suggests that the onset of dementia can be prevented or delayed if one gets into the habit of dozing for even as little as half an hour every day. This is a positive breakthrough and has given hope to researchers and dementia experts around the world. However, a number of limitations have held this research from being conclusive. First, the data that has produced the above research has been taken from a set that had only white men and women from the UK. Second, the exact length of a nap that would be optimally beneficial to the brain is unclear. Third, whether or not the same benefits would be observed in those who are not genetically predisposed to taking naps is yet to be seen.

While experts such as Professor Tara Spires-Jones, President of the British Neuroscience Association, a group leader at the UK Dementia Research Institute, and Deputy Director of the Centre for Discovery Brain Sciences at the University of Edinburgh are aware of the limitations in the existing research, they welcome these kinds of studies that would help them further the cause of preventing or delaying neurodegenerative diseases among aging men and women, especially when they are associated with sleep.