A destabilization theory on health impairments by night- and shift work--some tests about its predictive value

270 blue collar workers (181 shift and 89 day workers) of an Austrian oil refinery were investigated in 1976/77. 125 of them (60% of those still employed) were reinvestigated in 1981/82 (91 shift and 34 day workers). Subjects were interviewed about family situation, working conditions, sleep quality, risk factors and health problems. These informations were used for a partial test of our destabilization hypothesis, which states that a dynamic equilibrium between the degree of adaptation to the working sphere, the social sphere and the recreation sphere is a necessary condition for the preservation of health and that shift work, by its direct impact on all these activity spheres, tends to disturb the equilibrium, thus leading either directly or by increasing risk factors to diminished wellbeing and health impairment. It could be demonstrated that the causal structures of the formation of health problems differ considerably between shift and day workers in the predicted way. Furthermore, it was shown that shift and day workers differ with respect to the amount of destabilization and that within shift workers the degree of destabilization is a useful predictor of health impairment.