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Working hours and the onset of depressive disorder: a systematic review and meta-analysis
  1. Kazuhiro Watanabe1,2,
  2. Kotaro Imamura1,
  3. Norito Kawakami1
  1. 1Department of Mental Health, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
  2. 2Research Fellow of the Japan Society for the Promotion of Science
  1. Correspondence to Professor Norito Kawakami, Department of Mental Health, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; nkawakami{at}


This systematic review and meta-analysis aimed to examine whether working beyond the standard working hours was associated with a greater risk of depressive disorder among workers included in published prospective studies. This manuscript was prepared according to the PRISMA guideline checklist. A database search was conducted using MEDLINE (PubMed), PsycINFO, and PsycARTICLES using a relevant set of keywords. The eligibility criteria were as follows: (1) participants were adult workers; (2) exposure was defined as overtime work; (3) outcome were depressive disorders clinically diagnosed or assessed by a structured interview and (4) the study design was prospective or cohort. 7 studies were identified in the systematic review and meta-analysis. Overtime work was associated with a small, non-significant, elevated risk of depressive disorder (pooled relative risk=1.075; 95% CI 0.834 to 1.387; p=0.575) in a random effects model. The association tended to be greater for women. The risk of working 50 or more hours per week was slightly but not significantly increased (pooled relative risk=1.241; 95% CI 0.880 to 1.750; p=0.218). The effect of overtime work on depressive disorder remains inconclusive and may be small if not negligible. Sex differences and the effect of longer working hours on depressive disorder should be addressed in the future.

Trial registration number Prospero CRD42015020003; Results.

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  • Contributors KW, KI and NK have made substantial contributions to conception, design, analysis, interpretation of data, and reporting of the work described in the article. NK is responsible for the overall content as a guarantor.

  • Funding The present study was supported by the Health and Labor Sciences Research Grant 2015–2017 (H27-Rodo-Ippan-004) from the Ministry of Health, Labour and Welfare, Japan.

  • Disclaimer The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.