Habitual sleep duration and insomnia and the risk of cardiovascular events and all-cause death: report from a community-based cohort

Abstract

Study objectives: To investigate the relationship between sleep duration and insomnia severity and the risk of all-cause death and cardiovascular disease (CVD) events.

Design: Prospective cohort study.

Setting: Community-based.

Participants: A total of 3,430 adults aged 35 years or older.

Intervention: None.

Measurements and results: During a median 15.9 year (interquartile range, 13.1 to 16.9) follow-up period, 420 cases developed cardiovascular disease and 901 cases died. A U-shape association between sleep duration and all-cause death was found: the age and gender-adjusted relative risks (95% confidence interval [CI]) of all-cause death (with 7 h of daily sleep being considered for the reference group) for individuals reporting < or = 5 h, 6 h, 8 h, and > or = 9 h were 1.15 (0.91-1.45), 1.02 (0.85-1.25), 1.05 (0.88-1.27), and 1.43 (1.16-1.75); P for trend, 0.019. However, the relationship between sleep duration and risk of CVD were linear. The multivariate-adjusted relative risk (95% CI) for all-cause death (using individuals without insomnia) were 1.02 (0.86-1.20) for occasional insomnia, 1.15 (0.92-1.42) for frequent insomnia, and 1.70 (1.16-2.49) for nearly everyday insomnia (P for trend, 0.028). The multivariate adjusted relative risk (95% CI) was 2.53 (1.71-3.76) for all-cause death and 2.07 (1.11-3.85) for CVD rate in participants sleeping > or = 9 h and for those with frequent insomnia.

Conclusions: Sleep duration and insomnia severity were associated with all-cause death and CVD events among ethnic Chinese in Taiwan. Our data indicate that an optimal sleep duration (7-8 h) predicted fewer deaths.

Figure 1

Relationship between habitual sleep duration and the risks of all-cause death (left) and CVD event (right). The multivariate adjusted relative risk is plotted as a function of the baseline sleep duration value with the 95% confidence bands shown as the shaded areas

Figure 2

Joint effects of sleep duration and insomnia frequency for all-cause death and CVD events during median 15.9 y of follow-up, adjusting for age, gender, body mass index, smoking, current alcohol drinking, marital status, education level, occupation, regular exercise, family history of coronary heart disease, baseline hypertension, diabetes, cholesterol, HDL, triglyceride, glucose, and uric acid level