Abstract
BACKGROUND: The association between daytime napping and cognition is not well-studied in older adults. This study aimed to examine the associations between self-reported afternoon nap duration and change in cognition after 2-year follow-up in Chinese older adults. METHODS: A total of 3,037 individuals aged 60 years and older from the China Health and Retirement Longitudinal Study baseline and 2-year follow-up were included. Overall cognition was assessed by three interview-based sub-measures of orientation to time and attention, episodic memory, and visuospatial abilities. Change scores in cognition were calculated within subjects as follow-up minus baseline levels. Based on self-reported nap duration, older adults were grouped into: (i) Non-nappers (0 minutes); (ii) Short nappers (<30 minutes); (iii) Moderate nappers (30-90 minutes); and (iv) Extended nappers (>90 minutes) at baseline and follow-up. RESULTS: Change in cognition was significantly associated with both baseline napping and changes in napping habits from baseline to follow-up, controlling for age, gender, education, body mass index, depression, mobility, instrumental activities of daily living, nocturnal sleep duration, and cognition at baseline. Extended nappers at baseline performed significantly worse with respect to change of overall cognition from baseline to follow-up than non-nappers, short nappers, and moderate nappers. People who napped less than 90 minutes at both assessments performed significantly better from baseline to follow-up compared to non- or extended nappers at both assessments. CONCLUSION: Results suggest that afternoon naps less than 90 minutes may be beneficial for cognition in older adults, while long afternoon naps may be detrimental.