Twenty-four-hour shift work, depressive symptoms, and job dissatisfaction among Japanese firefighters.

Background: The influence of a 24-hr shift-work burden on firefighters' mental health has not been fully investigated. The purpose of this study is to clarify the relationships between specific workload items among firefighters engaged in 24-hr shift work and job stress as estimated by the generic job-stress questionnaire on depressive symptoms and job dissatisfaction from the National Institute for Occupational Safety and Health (NIOSH).

Method: The subjects were 1,301 firefighters. The questionnaire covered age, gender, job type, job class, marital status, smoking and drinking habits, number of attendances, turnout time, extra work hours, average nap-time, the Center for Epidemiologic Studies Depression Scale (CES-D), and questions from the NIOSH generic job-stress questionnaire, including those on job satisfaction.

Results: In multivariate logistic regression analyses, a model that included all variables except the measures from the NIOSH generic job-stress questionnaire showed that shorter nap-time had significant higher odds ratios (ORs) for depressive symptoms and job dissatisfaction, but the significances disappeared in a fully adjusted model. In fully adjusted logistic regression analyses, low quantitative workload, low variance in workload, high intra- and intergroup conflict, low social support from a supervisor, high role conflict and ambiguity, and low self-esteem had significant higher ORs for depressive symptoms and/or job dissatisfaction.

Conclusions: Amount of workload, variance in workload, intra- and intergroup conflict, social support from a supervisor, role conflict and ambiguity, and self-esteem were significantly related to depressive symptoms and/or job dissatisfaction among Japanese firefighters. Moreover, inadequate nap-time may affect their mental health.