Abstract:

Objective To investigate the relationship between afternoon nap and nocturnal sleep in middle and old aged community residents. Methods A total of 478 residents aged between 45 and 80 years were selected for face-to-face survey by cluster sampling method from 5 communities in 2 districts of Shanghai from September 2010 to March 2011. Pittsburgh sleep quality Index (PSQI) questionnaire was employed to evaluate the sleeping quality, Montreal cognitive assessment (MoCA) questionnaire was adopted to the assess the cognition function, and self-designed questionnaire was used to obtain the basic information of residents. According to afternoon nap frequencies, residents were divided into frequent afternoon nap group (≥3 times/week), occasional afternoon nap group (1 to 2 times/week) and control group (≤3 times/month). Results There were 443 valid questionnaires, with the effective rate of 92.68%. The mean age and waist circumference in frequent afternoon nap group were significantly higher than those in control group (P<0.01), but the cognition score in frequent afternoon nap group was significantly lower than that in control group (P<0.01). There were significant differences in the degree of education, employment status and self-report rate of chronic diseases between frequent afternoon nap group and control group (P<0.05 or P<0.01). After adjustment by factors such as age, degree of education, employment status, waist circumference, self-report rate of chronic diseases and cognition status, the sleep disorder score, daytime function score and total PSQI score in frequent afternoon nap group were significantly higher than those in occasional afternoon nap group and control group (P<0.05 or P<0.01), the total bed time in frequent afternoon nap group and occasional afternoon nap group was significant less than that in control group (P<0.01), and there was no significant difference in sleep latency, sleep duration and sleep efficiency among three groups (P>0.05). Conclusion The increase of afternoon nap frequency is closely associated with the poor nocturnal sleep quality of middle and old aged people, while there is no sufficient evidence that afternoon nap frequency is related to nocturnal sleep time pattern.

Key words: afternoon nap frequency, sleep quality, middle and old aged person