It was hypothesized, based on the cybernetic stress model, that the occupational stress-strain relationship is moderated by private self-consciousness (PSC) and control. If the possibility to control is perceved as favourable, high PSC was assumed to buffer against strain by inceasing the likelihood of active coping with stressors. In the opposite case, when the possibilities of controlling job stressors are experienced as low, high PSC was assumed to exacerbate the relationship between stress and strain, because paying attention to internal reactions to stressors beyond one's control only intensifies the experience of distress. Support for these hypotheses was obtained by the questionnaire method and hierarchical moderated regression analyses with a sample of 377 nurses. Consistently with the cybernetic model, the effects of work overload on mental strain symptoms depended on perceived control, especially among high PSC individuals. Work overload produced fewest mental symptoms when PSC and control were high, and most mental symptoms when PSC was high but control low. If PSC was low, the effects of stressors were between the two extremes. Implications for further research on the cybernetic stress model are discussed.