Long working hours and risk for hypertension in Japanese male white collar workers

Abstract

Study objective-To evaluate the association of long working hours with the risk for hypertension. Design-A five year prospective cohort study. Setting-Work site in Osaka, Japan. Participants-941 hypertension free Japanese male white collar workers aged 35-54 years were prospectively examined by serial annual health examinations. Men in whom borderline hypertension and hypertension were found during repeated surveys were defined as incidental cases of borderline hypertension and hypertension. Conclusions-These results indicate that long working hours are negatively associated with the risk for hypertension in Japanese male white collar workers. (J Epidemiol Community Health 2001;55:316-322) With regard to the eVect of working hours on health, long working hours have been shown to be related to various disorders and diseases such as chronic fatigue, 1 2 musculoskeletal complaints, 3 mental stress or health, 4-6 dissatisfaction with work, 7 depression, 8 and coronary heart disease. 9 10 In particular, "Karoshi", or sudden unexplained death in relatively young workers, has received considerable attention as a social problem in Japan.11 It is widely thought that strenuous work for long hours, which is so much a part of the modern Japanese culture, is a major contributory factor for Karoshi resulting from hypertensive or arteriosclerotic disease.As for the association between long working hours and blood pressure, the influence of long working hours on blood pressure is related to sympathetic nerve activity and concentrations of counterregulatory hormones that accompanies psychological stress 12 13 and physical activity.14 As overtime work is very often accompanied by such stress and physical activity, it is reasonable to expect an association between long working hours and the risk for hypertension. However, there is no convincing evidence to support the view that long working hours contribute to long term blood pressure and predisposition to hypertension. Therefore, it is necessary to conduct a longitudinal study to clarify the relation between long working hours and the risk for hypertension.In this report on a longitudinal population study based on serial annual health examinations at the workplace, we have tried to prospectively examine the association between long working hours and the risk for hypertension in hypertension free Japanese male white collar workers. Methods STUDY COHORTOur study is an ongoing cohort investigation designed to clarify risk factors for major diseases, including hypertension, dyslipidaemia, and diabetes among Japanese male white collar workers, not working in a shift system at T Corporation, one of the biggest building contractors in Osaka, Japan. The Industrial Safety and Health Law in Japan requires the employer to conduct annual health examinations of all employees; the employee data, which are anonymised, are available for research with the approval of the employer. To evaluate the association of long working hours with the risk for hypertension, a surveillance of the in...

21st International Symposium on Shiftwork and Working Time: The 24/7 Society – From chronobiology to practical life

“…Data from more than Japanese 50,000 workers from 4 companies were evaluated. The results showing an inverse association between overtime work and prevalence of hypertension contradicted two former studies (Artazcoz et al, 2009;Yang et al, 2006), but confirmed others (Wada et al, 2006;Nakanishi et al, 2001). Despite the large database, the authors highlighted the cross-sectional design as the main study limitation that left the possibility open of residual effects of potential confounders and differences in assessments of overtime and blood pressure evaluation among the companies.…”

Long workhours and health

“…Two studies (39,40) concerning the same all-male study population found that long workhours were associated with a reduced risk of developing hypertension. Nakanishi et al (39) showed that, over a 3-year period, those who worked 10 hours or more a day had an increased risk of developing hypertension (RR=0.58).…”

“…Two studies had a case-referent design (28,46). There were five independent longitudinal studies (35,36,(38)(39)(40)(41), and two repeatedmeasures studies (30,47). Table 1.…”

“…In one case, two articles (49,50) were written based on the same sample but with different dependent measures. Two other articles (39,40) concerned follow-up studies on the same population, one after 3 years and one after 5 years. It should be kept in mind that the results of these studies are not statistically independent.…”

Moderating Effects of Psychological Job Strain on the Relationship between Working Hours and Health: An Examination of White‐Collar Workers Employed by a Japanese Manufacturing Company

“…For example, Nakanishi et al 4,5) observed the onset of hypertension in office workers at a Japanese construction company and found an inverse relationship: with the number of working hours, the percentage of those having developed hypertension decreased. The authors 6) also examined the relationship between working hours and the onset of mental and circulatory disorders, and could not find detrimental effects of long working hours.…”