There’s no need to feel guilty about having that much-needed nap during the day as new research has found it could have some surprising benefits.

A team of researchers from the University of Pennsylvania, Philadelphia conducted a study that found taking an hour-long nap after eating lunch could keep your brain five years younger in older people.

Junxin Li and colleagues examined almost 3,000 adults aged 65 and over living in China, 60 percent of whom admitted to having a 30-90 minute nap after lunch for most days. Tests were conducted to examine their cognitive abilities including maths problems and basic memory tests.

The results found those participants who took an hours nap after lunch performed much better in the tests than those who didn’t have some short-term shut-eye.

However, interestingly the length of the nap was important – anything less or more than an hour saw a dip in memory and maths solving. In fact, it was around a four to six times decrease which was also seen in those that didn’t nap at all.

“These people also experienced about the same decline in their mental abilities that a five-year increase in age would be expected to cause. Cognitive function was significantly associated with napping. Comparisons showed that moderate nappers had better overall cognition than non-nappers or extended nappers. Non-nappers also had significantly poorer cognition than short nappers,” explained Li, who led the research.

Despite the results and strong association between napping for an hour and increased mental abilities, the team were unable to identify the cause-and-effect relationship.

Details of the study were published in the Journal of the American Geriatrics Society.