The relationship between job strain and blood pressure at work, at home, and during sleep.

Eleven normotensive workers in "high strain" jobs, defined by the combination of high psychological work load and low worker control, were compared with 26 normotensive workers in "low strain" jobs on ambulatory blood pressure (BP) at work, at home in the evening, and during sleep. High strain workers' systolic BP was higher at work and at home in the evening, after adjusting for prework casual BP, body mass index, gender. Type A behavior, and caffeine consumption. Under certain conditions, systolic BP during sleep and diastolic BP at work were higher as well. Men and women, and Type A and Type B workers, were indistinguishable in job strain effects on BP. Type A workers tended to hold "active" (high demand, high control) jobs, and Type B workers "passive" jobs. More research is needed to distinguish more clearly job strain as 'cause' of observed BP effects from job strain as mere 'correlate.'