A comparative study of behavioural, physical and mental health status between term-limited and tenure-tracking employees in a population of Japanese male researchers

OBJECTIVES: Traditional lifelong employment systems have been changing rapidly in Japan. The aim of this study was to assess the health impacts of term-limited employment systems that have recently been introduced into Japanese academic institutes. STUDY DESIGN: Cross-sectional. METHODS: A total of 514 male researchers (275 term limited and 239 tenure track) were compared in terms of behavioural, physical and mental status at annual health examinations. At these examinations, working hours and health-related lifestyles were examined using a self-completed questionnaire. Clinical structured interviews of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) were used to detect major depression. RESULTS: The term-limited researchers tended to work longer hours (P<0.001), drink alcohol more frequently (P<0.001) and eat breakfast less regularly (P<0.001) compared with the tenure-track researchers. Although the prevalence of DSM-IV major depression was comparable (P>0.05) between the two groups, fatigue was more prevalent (P=0.027) in the term-limited researchers than in the tenure-track researchers, adjusting for the effects of age. Compared with colleagues working in the same laboratories, the term-limited researchers worked longer hours, irrespective of fatigue, whereas only the fatigued tenure-track researchers worked longer hours. In the total sample, the fatigued researchers tended to belong to laboratories where their colleagues, on average, worked longer hours, compared with the non-fatigued researchers. CONCLUSIONS: These results imply that the term-limited researchers suffered more from fatigue, due to longer working hours, than their colleagues, and that organized, rather than personal, interventions with respect to the working environment may be effective in reducing overload in such workplaces.