Chinese scientists from Shanghai claim that daytime sleep in old age improves brain function and memory, and is also associated with increased fluency and confident orientation in space.
More than 2,000 people aged 60 and over participated in the scientific project. Of this number, approximately 1,500 people had more or less regular afternoon naps, and 680 people did not. On average, at night, subjects from both groups slept for 6–7 hours. Afternoon nap was defined as a period of sleep lasting at least 5 minutes in a row, but not more than 2 hours. The frequency of daytime sleep varied among the respondents from 1 time per week to daily.
The researchers compared the scores on cognitive function tests for participants from both groups. It turned out that significantly higher results were shown by people who slept during the day. Participants who had an afternoon nap demonstrated more confident spatial coordination, higher verbal fluency, and better memory.
Scientists believe that we need sleep to regulate the immune response. Perhaps daytime sleep is an evolutionary response to inflammation. This is confirmed by the fact that sick people with a high level of inflammatory processes also sleep more.