The Effects of Sleep Duration on the Incidence of Cardiovascular Events among Middle-Aged Male Workers in Japan

• Published in: Scandinavian Journal of Work, Environment ＆ Health Vol. 37; no. 5; pp. 411 - 417
• Main Authors: Hamazaki, Yuko, Morikawa, Yuko, Nakamura, Koshi, Sakurai, Masaru, Miura, Katsuyuki, Ishizaki, Masao, Kido, Teruhiko, Naruse, Yuchi, Suwazono, Yasushi, Nakagawa, Hideaki
• Format: Journal Article
• Language: English
• Published: Helsinki Scandinavian Journal of Work, Environment ＆ Health 01-09-2011; Finnish Institute of Occupational Health; National Institute of Occupational Health; National Research Centre for the Working Environment; Scandinavian journal of work, environment & health; Scandinavian Journal of Work, Environment & Health; Nordic Association of Occupational Safety and Health (NOROSH)
• Subjects: Adult; Alcohol; Alcohol drinking; Biological and medical sciences; Blood pressure; Cardiology. Vascular system; Cardiovascular disease; Cardiovascular Diseases - epidemiology; cardiovascular event; cardiovascular risk factor; Continuous variables; Coronary heart disease; Death, Sudden, Cardiac - epidemiology; Employees; Factories; follow-up study; Health risks; Heart; Humans; Hypertension; japan; Japan - epidemiology; Male; Male employees; males; Medical sciences; Middle age; Middle Aged; Mortality; Myocardial infarction; Neurology; Occupational Health; Predisposing factors; Proportional Hazards Models; Questionnaires; Retirement; Risk Factors; Sleep; sleep duration; Stroke; Stroke - epidemiology; Strokes; Surveys and Questionnaires; Vascular diseases and vascular malformations of the nervous system; Work hours; worker; Working hours; Workloads; Asia; Japan; cardiovascular disease; coronary heart disease; follow-up study; stroke; cardiovascular risk factor; Male; Cardiovascular disease; Occupational exposure; Incidence; Vascular disease; Adult; Worker; Sleep wake cycle; Cerebrovascular disease; Public health; Human; Nervous system diseases; Stroke; Middle age; Duration; Coronary heart disease; Cerebral disorder; Sleep; Follow up study; Central nervous system disease; Risk factor; Cardiovascular risk; Occupational medicine
• ISSN: 0355-3140; 1795-990X
• DOI: 10.5271/sjweh.3168

Objectives Although previous epidemiological studies have investigated the relationship between sleep duration and various cardiovascular events, the results have been inconsistent. Accordingly, we conducted a follow-up survey to investigate the relationship between sleep duration and cardiovascular events among male workers, accounting for occupational factors that might confound the true relationship. Methods A total of 2282 male employees aged 35–54 years based in a factory in Japan were followed for 14 years. The risk of cardiovascular events was compared among 4 groups stratified based on sleep duration at baseline (<6, 6–6.9, 7–7.9, and ≥8 hours). Cardiovascular events included stroke, coronary events and sudden cardiac death. The hazard ratios for events were calculated using a Cox proportional hazards model, with the 7–7.9-hour group serving as a reference. The model was adjusted for potential confounders including traditional cardiovascular risk factors and working characteristics. Results During 14 years of follow-up, 64 cardiovascular events were recorded including 30 strokes, 27 coronary events and 7 sudden cardiac deaths. After adjustment for possible confounders, the hazard ratios for cardiovascular and coronary events in the <6-hour group were 3.49 [95% confidence interval (95% CI) 1.30–9.40] and 4.95 (95% CI 1.31–18.73), respectively. There was no significant increment in the risk of stroke for any sleep duration groups. Conclusion Short sleep duration (<6 hours) was a significant risk factor for coronary events in a Japanese male working population.