Association between sleep quality and body mass index among Chinese nonagenarians/centenarians.

We examined the individual association between body mass index (BMI) and sleep quality among the very elderly. The present study analyzed data from survey that was conducted on all residents aged 90 years or more in a district, there were 2,311,709 inhabitants in 2005. Subjects were divided into four groups according to quartile of BMI (<16.6, 16.6-18.9, 18.9-21.1, >21.1 kg/m(2)) and according to classification criteria of underweight, normal weight, overweight, and obesity in BMI (<18.5, 18.5-23.0, 23.0-27.5, >27.5 kg/m(2)), respectively. Sleep quality was measured using The Pittsburgh Sleep Quality Index (PSQI). Sleep quality included quality classification and scores, sleep duration, sleep latency, and sleep efficiency. The subjects included in the statistical analysis were 216 men and 444 women. According to quartile of BMI or classification criteria of underweight, normal weight, overweight, and obesity in BMI, none of the differences in sleep quality scores, sleep latency, sleep duration, sleep efficiency percentage, and prevalence of poor sleep quality was significant among different BMI groups. The difference in BMI between subjects with good and poor sleep quality was non-significant. Unadjusted and adjusted multiple logistic regression showed that none of the BMI groups had a function of decreasing the risk for poor quality. Among longevity Chinese, there is no association between BMI and sleep quality.