Background Adequate sleep duration is vital for a healthy life. Insufficient or excessive sleep duration has been closely linked with elderly health.
Objective This study is designed to assess the relationship between sleep duration and body fat percentage among the elderly aged 60 years and above from 15 provinces (municipalities, autonomous regions) (hereinafter referred to as 15 provinces) of China in 2015.
Methods Data were derived from the China Nutritional Transition Cohort Study 2015, where a total of 4 509 participants aged 60 years and above with complete information on demographic characteristics, sleep duration, diet, physical activity, and body fat percentage were included in the final analysis. Detailed dietary intake information was obtained by a combined 3-day 24-hour dietary recall and weighing method. Daily energy intake for each individual was calculated by an established food composition table. Physical activity data were collected by relevant questionnaire survey. Body composition was measured by bioelectric impedance analysis. Sleep duration was divided into three groups: < 7h/d (insufficient sleeping), 7-9h (sufficient sleeping), and ≥ 9h (excessive sleeping). Non-parametric test was used to compare the differences in sleep duration among different gender and age groups. Quantile regression analyses were used to investigate the relationship between sleep duration and body fat percentage.
Results The median of daily sleep duration was 8.0 h of the elderly residents aged 60 years and above in the 15 provinces of China. The proportion of insufficient sleeping was 18.4%. The proportion of excessive sleeping was 20.3%. Significant gender differences were found in sleep duration. The proportion of insufficient sleeping was lower in males (16.7%) than in females (19.9%). The proportions of sufficient and excessive sleeping were higher in males (62.3% and 21.0%) than in females (60.3% and 19.7%). The coefficients estimated by quantile regression analyses were negative between sleep duration and body fat percentage in all percentiles for elderly males and between sleep duration and body fat percentage in low percentiles for elderly females, and were positive between sleep duration and body fat percentage in high percentiles for elderly females. All the quantile regression coefficients were not statistically significant (P>0.05).
Conclusion Both insufficient and excessive sleep duration are found among Chinese seniors in the 15 provinces of China. The effect of sleep duration on body fat percentage is probably insignificant.
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