Previous studies have shown that napping helps to boost performance. According to a very recent study by Paz et al.¹ regularly taking a nap during the day can help to slow down the natural decline in brain volume and maintain brain health.

Before I get into discussing the study I want t say something about the ability to nap: There are those who are genetically ‘programmed’ to be able to nap, and there are those who aren’t. A previous study² from 2021 had shown that some people carry genetic variants which make it more likely that the person naps. So there is a reason why some will find it easy to close their eyes and fall asleep while others merely rest their eyelids in the early afternoon. (Self-disclosure: I fall into the latter group.)

Background to the nap study

As we age, our brain slowly shrinks and our cognitive functions such as memory for example also decline. In a way one could say that assessing the brain’s volume gives a hint whether there is any loss of brain function. Researchers are interested in finding out what behaviours or habits might impact these changes – in a good or bad way. Such behaviours are called ‘modifiable risk factors’.

Key finding of the new study 

The recent study by Paz et al.¹ set out to shed light on the relationship between napping, brain volume and cognitive abilities in healthy adults. Their findings suggest that regular daytime naps might help to ward of brain illnesses such as dementia.

What did the current study do?

Paz et al. used data from the UK Biobank (UKB) to which individuals between 40 to 69 years (predominately White-British) had contributed. This dataset includes genetic data, MRI (magnetic resonance imaging) scans (used to visualise brain structure), and surveys for some but not all of the volunteers. One of these questionnaires asked about napping; volunteers said that they (1) “Never/ Rarely” or (2) “Sometimes”, or (3) “Usually” napped. (The fourth group said they preferred not to answer.) This questionnaire data was then compared to the genetic data for napping. Crucially, it mated.

The researchers then used Mendelian Randomization (MR)* to investigated whether there’s a causal relationship between napping, brain volume and cognitive abilities in healthy adults, i.e. whether taking regular naps sustains your cognitive abilities and affects the structure of your brain.

The researchers compared genetically programmed nappers with non-nappers with regards to their brain volume and cognitive abilities. They found that the brains of nappers shrank at a slower rate – or remained bigger for longer (depending on how you wan to look at it). The difference is between 2.6 to 6.5 years.

However, there was no difference between the two groups when comparing cognitive function (such as reaction times and visual memory) and the volume of the hippocampus.

Important caveat

The study drew on data from White European participants only. That makes it difficult to generalise the findings, and ideally the study should be replicated with a more divers group.

How can you nap?

My answer to clients asking whether it is ok to nap is: It depends. If you sleep well at night, and you can nap, then do it. Keep it to 30 minutes and don’t nap after 3pm. If you are a non-napper, then you can simply allow yourself to close your eyes and rest for a moment.

But if you struggle to sleep well at night, maybe because of insomnia or sleep apnea, and if you experience excessive daytime sleepiness, then go and speak to your GP or sleep specialist.

Do you have any questions on napping or your night-time sleep? Send me an email or book an initial call with me and we can explore what’s going on together. 

Warmly,

Dr Kat

*Mendelian Randomization is a statistical method assessing the influence of modifiable risk factor (e.g. napping) has on health. To do this MR considers the natural variation of genes encoding a specific function.

References:

¹Paz et al., 2023: Is there an association between daytime napping, cognitive function, and brain volume? A Mendelian randomization study in the UK Biobank. Sleep Health 9:3.

²Dashti et al., 2021: Genetic determinants of daytime napping and effects on cardiometabolic health. Nat Commun 12: 900.