Optimal sleep duration for cardiovascular prevention in Eastern Mediterranean populations: insights from a prospective cohort study

Abstract

Introduction There is a complex relationship between sleep duration and the risk of developing cardiovascular diseases. This study aimed to identify sleep duration trajectories in a healthy population and examine their associations with incident cardiovascular disease (CVDs) in the Eastern Mediterranean Region (EMR). Methods This prospective population-based cohort study included 5,432 participants free of cardiovascular disease at baseline (2001-2013). The associations between sleep duration trajectories and CVD risk were analyzed using multivariable Cox proportional hazards models. Cubic and restricted cubic spline models were applied to identify the optimal sleep duration associated with the lowest CVD risk and to examine the shape of the relationship between total daily sleep duration and CVD hazard ratios. Results We observed a U-shaped association between total daily sleep duration and incident CVD after adjusting for demographic characteristics, lifestyle factors, and health status. Compared with individuals sleeping below 5 h, adjusted hazard ratios (HRs) for CVD were as follows: 5-6 h (HR = 0.930, 95CI: 0.70-1.22, p-value = 0.61), 6-7 h (HR = 0.772, 95CI: 0.59-0.99, p-value = 0.04), 7-8 h (HR = 0.764, 95CI: 0.60-0.97, p-value = 0.03), 8-9 h (HR = 0.701, 95CI: 0.53-0.91, p-value = 0.01), 9-10 h (HR = 0.755, 95CI: 0.54-1.05, p-value = 0.10], and > 10 h (HR = 0.816, 95CI: 0.54-1.22, p-value = 0.01). According to the results of the cubic spline curves, the lowest risk was identified at a sleep duration of 8.38 h. Conclusions The internationally recommended sleep duration may not be ideal for Middle Eastern populations. In this Iranian cohort, approximately 8.4 h of total daily sleep was associated with the lowest CVD risk.