Objective: Our objective was to examine the impact of shift work on mental health at the population level. We expected that this impact would depend on duration of exposure, type of shift work, and gender.
Methods: We analyzed longitudinal data (1995-2005) from the British Household Panel Survey. From the 2005 wave, we selected a subsample of people aged 21-73 years who had been followed annually from 1995 to 2005. We used responses in 2005 to the General Health Questionnaire (GHQ, 12-item) and self-reported anxiety/depression as dependent variables. Controlling for age, marital status, education, number of years working in six occupational categories (1995-2005), and baseline mental health, we performed nested logistic regression models to examine the effect of the duration of night work and varied shift patterns on mental health for men and women.
Results: Undertaking night work for > or =4 years in men was associated with an increased risk of having a GHQ score reflecting mental ill health and reporting anxiety/depression [odds ratios (OR) 2.58, 95% confidence interval (95% CI) 1.22-5.48; OR 6.08, 95% CI 2.06-17.92, respectively]. Women were significantly more likely to report anxiety/depression (OR 2.58, 95% CI 1.53-4.35 ) and to have a GHQ score reflecting mental ill health (OR 4.17, 95% CI 1.45-11.98), after working varied shift patterns for 2-3 years, and >/=4 years, respectively.
Conclusions: Different types of shift work had a differential impact on mental health, but this impact varied according to gender. Women's mental health was more adversely affected by varied shift patterns, while night work had a greater negative impact on men's mental health.