Objective: To determine the effects of the job demands-control model on arterial blood pressure, serum total cholesterol, and smoking in male daytime and rotating-shift workers in Japan.
Methods: The survey was conducted for all employees of an electrical factory in Japan using a mailed questionnaire concerning three job stressors, i.e., job overload, work-pace control, and work-site social support. A blood sample was taken at the same time. Data on 1703 male daytime workers and 1 173 male rotating-shift workers were analyzed. Multiple logistic regression or analysis of covariance (ANCOVA) were employed to determine the effects of the job stressors on systolic and diastolic blood pressure, serum total cholesterol, and smoking with control for other covariates.
Results: Among daytime workers, systolic and diastolic blood pressures were highest in the "high-strain" (i.e., higher job overload + lower work-pace control) group; ANCOVA indicated that a two-way interaction between job overload and work-pace control was significant (P < 0.01). This tendency was not observed among rotating-shift workers. The number of cigarettes smoked per day was greater in groups with lower work-pace control and lower work-site social support among daytime workers (two-way interaction between these two job stressors, P < 0.05); it was greater in groups with lower work-site social support among rotating-shift workers (main effect of work-site social support, P < 0.05).
Conclusions: Our study suggest that job strain as defined in the job demands-control model is associated with increased systolic and diastolic blood pressures in male daytime workers in Japan. Smoking might be affected by lower work-site social support.