Adults need between 7 to 9 hours of sleep per night to maintain physical and mental health. Sleep helps us to solidify and consolidate short-term memory to long-term memory.
After sleep, people tend to improve information retention and perform better in memory tests. Skipping the recommended amount of sleep however, interferes with the brain’s ability to form new memories. Sleep may be a trouble-free way to improve long-term retention of information. Participants of a study in China who slept between learning sessions could recall 10 to 16 words on a memory test, while those who had not slept only recalled 7.5 words, on average.
Other research found that in adults aged 65 and older, taking an hour-long nap in the afternoon improved performance on cognitive tests compared with individuals who did not nap. Those who took shorter or longer naps, or who did not nap at all, exhibited declines in their mental abilities equal to what would be expected of a 5-year age increase.
Detailed Research Findings: Afternoon Napping and Cognition in Chinese Older Adults: Findings from the China Health and Retirement Longitudinal Study Baseline Assessment
In this cross-sectional analysis, the association between self‐reported post lunch napping duration and cognition was examined in a nationally representative sample of 2,974 community-dwelling Chinese older adults. The results support the hypothesis that a moderate-duration nap taken during the post lunch dip is associated with better overall cognition. Older adults who did not nap or napped longer than 90 minutes (extended nappers) were significantly more likely than those who napped for 30 to 90 minutes after lunch (moderate nappers) to have lower overall cognition scores after adjusting for possible confounders. The negative association between nap duration and night time sleep duration that was hypothesised was not supported in the analysis: extended nappers slept significantly longer than non-nappers and moderate nappers. Non-nappers slept the least at night of the napping groups.