Association of self-reported nighttime sleep duration with chronic kidney disease: China Health and Retirement Longitudinal Study.

INTRODUCTION: The cohort study aimed to assess the association of nighttime sleep duration and the change in nighttime sleep duration with chronic kidney disease (CKD), and whether the association between nighttime sleep duration and CKD differed by daytime napping.

METHODS: This study included 11677 individuals of the China Health and Retirement Longitudinal Study (CHARLS) and used data from the 2011 baseline survey and four follow-up waves. Nighttime sleep duration was divided into three groups: short (<7h per night), optimal (7-9h), and long nighttime sleep duration (>9h). Daytime napping was divided into two groups: no nap, with a nap. We used Cox proportional hazards model to examine the effect of nighttime sleep duration at baseline and change in nighttime sleep duration on incident CKD, and a joint effect of nighttime sleep duration and nap time on onset CKD.

RESULTS: With a follow-up of 7 years, the incidence of CKD among those with short, optimal and long nighttime sleep duration was 9.89, 6.75, and 9.05 per 1000 person-years, respectively. Compared to individuals with optimal nighttime sleep duration, short nighttime sleepers had a 44% higher risk of onset CKD (hazard ratio [HR]: 1.44, 95% Confidence intervals [CIs]:1.21-1.72). Compared to participants with persistent optimal nighttime sleep duration, those with persistent short or long nighttime sleep duration had an increased risk of incident CKD (HR:1.44, 95%CI:1.15-1.80). We found a lower incidence of CKD in participants with short nighttime sleep duration and a nap (HR:0.74, 95%CI:0.60-0.93), compared to those with short nighttime sleep duration and no nap.

DISCUSSION/CONCLUSION: Short nighttime sleep duration and persistent long or short nighttime sleep duration were associated with a higher risk of onset CKD. Keeping persistent optimal nighttime sleep duration may help reduce CKD risk later in life. Daytime napping may be protective against onset CKD.