Associations of sleep duration and disturbances with hypertension in metropolitan cities of Delhi, Chennai, and Karachi in South Asia: Cross-sectional analysis of the CARRS study

Objectives: Sleep duration and disturbances may be risk factors for hypertension. Despite the high burden of hypertension in South Asia, little is known about this relationship in this region. Methods: We analyzed population-level cross-sectional data from the Centre for Cardiometabolic Risk Reduction in South Asia (CARRS) study that recruited representative samples of adults ≥ 20 years from three cities - Delhi, Chennai (India), and Karachi (Pakistan) during 2010-2011. We defined hypertension as self-reported treatment or measured blood pressure (BP) ≥140/90 mm Hg. Data on usual duration of sleep, insomnia, and snoring were collected using "The Sleep Habits Questionnaire" and excessive daytime sleepiness (EDS) using Epworth Sleepiness Score. Logistic and linear regression were done with hypertension and BP as outcome variables, respectively. Age, gender, education, wealth index, family history, and body mass index (BMI) were included as covariates. We used multiple imputation to account for missing variables. Results: Prevalence of hypertension was 30.1%. The mean (SD) sleep duration was 7.3 (1.2) hours. Insomnia, snoring, and EDS were present in 13.6%, 28.7%, and 4.6%, respectively. Moderate and habitual snoring were associated with increased odds of hypertension (odds ratio [OR] = 1.18, 95% confidence interval [CI] [1.04 to 1.33] and 1.47 [1.29 to 1.67], respectively), after adjusting for covariates. Rare, occasional, and frequent insomnia were associated with increased hypertension (OR 1.41 [1.12 to 1.77], 1.39 [1.16 to 1.67], and 1.34 [1.09 to 1.65], respectively). Sleep duration and EDS were not associated with hypertension. Conclusion: Self-reported snoring and insomnia were associated with hypertension in South Asia. This relationship needs further exploration through robust longitudinal studies in this region.