Gender- and age-specific associations between sleep duration and prevalent hypertension in middle-aged and elderly Chinese: a cross-sectional study from CHARLS 2011-2012.

Objectives: The impact of gender and age on the association between sleep duration and hypertension is not well known in Asians. The objective of this study was to analyse gender-and age-specific associations between sleep duration and prevalent hypertension in middle-aged and elderly Chinese. Design: Secondary analysis of a cohort sample. Setting: This study used data from the national baseline survey of the China Health and Retirement Longitudinal Study (CHARLS, 2011-2012), covering 150 counties/districts and 450 villages/resident committees from 28 provinces in China. Participants: Community-based subjects were drawn from the CHARLS through multistage probability sampling. Overall, this study included 9086 eligible subjects aged 45 years or above. Outcome measures: Self-reported sleep duration was obtained using a structured questionnaire. The mean of three measures of systolic blood pressure and diastolic blood pressure was calculated. By gender and age groups (45-60 years, middle-aged; >= 60 years, elderly), relationships between self-reported sleep duration and prevalent hypertension were examined using logistic regression models to estimate OR and 95% CIs. Results: Compared with the reference group (>= 7 and <8 hours/night), the group who had less sleep (<6 hours/night) had a higher likelihood of hypertension in the whole sample (OR 1.26, 95% CI 1.04 to 1.52). Significant ORs (95% CIs) of hypertension were 1.68 (1.17 to 2.42), 1.69 (1.11 to 2.59) and 2.21 (1.29 to 3.80) for <6, 6-7 (>= 6 and <7) and 8-9 (>= 8 and <9) hours/night, respectively, in middle-aged men but not women. Interestingly, a significant association was observed between long sleep duration (>= 9 hours/night) and hypertension in middle-aged women (OR 1.55, 95% CI 1.02 to 2.35) but not in men. Conclusions: Extremes of sleep duration increased the likelihood of prevalent hypertension in middle-aged Chinese depending on gender, suggesting that appropriate strategies for improvement in sleep health are required.