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Chronobiology International
The Journal of Biological and Medical Rhythm Research
Volume 38, 2021 - Issue 12
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Original Article

Impact of shift work on the risk of depression

, , , , , , , , & show all
Pages 1761-1775 | Received 30 Mar 2021, Accepted 26 Jul 2021, Published online: 12 Aug 2021
 

ABSTRACT

We studied the association between shift work and depressive symptoms in the prospective Heinz Nixdorf Recall Study, considering various demographic, lifestyle and work-related factors. Depressive symptoms were assessed using the Center for Epidemiologic Studies-Depression (CES-D)-Scale (≥17 points defined as high symptoms) and the Patient Health Questionnaire (PHQ) with a cutoff ≥9, or prescription of an anti-depressant. The definition of shift work included work hours outside 7:00 to 18:00, whereas night work was defined as a shift including work between 0:00 and 5:00. Poisson regression with robust error variances was calculated to estimate relative risks (RR) and 95% confidence intervals (CI), adjusted for age at follow-up, diurnal preference, monthly household income and education. Analyses were stratified by sex. We performed various sensitivity and stratified analyses to test the robustness of our results. At baseline, 1,500 gainfully employed subjects, 45–73 years of age and without a history of depression, were included. Until the 5-year follow-up, 896 participants were observed, and 486 participants survived through the 10-year follow-up. Although most analyses did not reach the level of formal statistical significance, women working night shifts tended to show increased relative risks for depressive symptoms according to the PHQ (RR = 1.78; 95% CI 0.71–4.45), in particular when working night shifts for ≥20 years (RR = 2.70; 95% CI 0.48–15.4). Stratification by age group revealed no increased risks among women above 60 years of age. Stratified analyses indicated that over-commitment was associated with higher risks for depressive symptoms among women (RR = 4.59; 95% CI 0.95–22.2 in the CES-D and RR = 12.7; 95% CI 2.89–56.1 in the PHQ). Exclusion of subgroups for the purpose of sensitivity analyses generally strengthened associations in women, whereas little evidence for an increased risk of depression remained among male shift workers. In summary, negative effects on depression were suggested among female shift workers, although results were based on small numbers. Among men, we did not identify consistently increased risks for depressive symptoms in relation to shift work.

Acknowledgements

We would like to thank the investigative group and the entire study staff of the Heinz Nixdorf Recall Study.

Data availability statement

The data right owners at the University of Duisburg-Essen may be contacted for data availability.

Disclosure statement

The authors do not declare any conflict of interest.

TB, KB, SR, KW and TBr, as staff of the Institute for Prevention and Occupational Medicine (IPA), are employed at the “Berufsgenossenschaft Rohstoffe und chemische Industrie” (BG RCI), a public body, which is a member of the study’s main sponsor, the German Social Accident Insurance. IPA is an independent research institute of the Ruhr University Bochum. The authors are independent from the German Social Accident Insurance in study design, access to the collected data, responsibility for data analysis and interpretation, and the right to publish. The views expressed in this paper are those of the authors and not necessarily those of the sponsor.

Supplemental data

Supplemental data for this article can be accessed on the publisher’s website.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

The study’s follow-up was funded by the German Social Accident Insurance (DGUV) [grant number FP 295]. We thank the Heinz Nixdorf Foundation (Germany) for the generous support of the Heinz Nixdorf Study. This study was also supported by the German Ministry of Education and Science (BMBF) and the Kulturstiftung Essen. The German Research Foundation supported the study [DFG project: ER 155/6-2] and funded the study of psychosocial factors [DFG project SI 236/8-1 and SI 236/9-1].

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