Do occupational factors mediate the association of shiftwork with mental health?

Background

We studied the mediating influence of occupational and social factors on the association between shift work and mental health in the population-based digital multicenter cohort DigiHero from Germany.

Methods

An online questionnaire assessing sociodemographic factors, shiftwork, general occupational conditions, depression and anxiety was completed by 42,577 residents from Germany in November 2023 (t1) and retrospectively during the SARS-CoV-2 pandemic in early 2022 (t0). Shiftwork was categorized as night work (0:00–5:00 a.m.), early shifts (before 7:00 a.m.), late shifts (after 6:00 p.m.), and other types. Associations with mental health according to the PHQ-9 (depressive symptoms) and GAD-7 (anxiety) were examined by ordinal regression models adjusted for study area, sex, age, and education and expressed as odds ratios (OR) with 95% confidence intervals (CI). Work-related and social factors were explored through mediation and stratified analyses.

Results

ORs for the association of night work with depression severity were higher at t0 compared to t1 (OR = 1.51; 95% CI 1.33-1.70 vs. OR = 1.27; 95% CI 1.14-1.41). Associations for anxiety were lower (e.g., OR = 1.11; 95% CI 1.0-1.24 at t1). Work-related mediators, particularly high work-privacy conflicts, which were highly correlated with depressive symptoms (OR = 5.70; 95% CI 5.27-6.17), exerted the strongest mediating effect on the association of shift/night work with depression or anxiety. Entering all work-related factors into the model, reduced associations below one at t1. At t0, an increased association of night work with depression severity persisted (OR = 1.24; 95% CI 1.09-1.41).

Conclusions

Work-privacy conflicts and occupational factors substantially mediated the association between shiftwork and mental health after the pandemic, underscoring the opportunity for employers to address these modifiable risks factors to reduce psychological strain among shift workers. (on behalf of the DiGiHero Consortium)

Key messages

• Shift and night work were associated with mental health, particularly during the SARS-CoV-2 pandemic.

• Social and occupational factors substantially mediated this association.