Introduction Contemporary work environments increasingly rely upon a 24-hour work cycle resulting in more employees exposed to shift work. Thirty percent of working age Canadians work evening, night and rotating shifts. Compared to regular daytime work, shift work has the potential for disturbing sleep patterns and disrupting circadian rhythms with adverse health effects.

Methods A population health study was conducted with 4,155 shift workers and 8,258 non-shift workers from the Atlantic PATH cohort. Linear and logistic regression models were used to assess the differences in i) self-reported mental health measures between shift workers and non-shift workers and ii) anthropometric measures (body adiposity) and self-reported cardiometabolic disease outcomes (obesity, diabetes, and cardiovascular disease).

Results Shift workers reported higher levels of each of the mental health domains. There was a significant increased risk of depression (OR=1.13, 95% CI, 1.00–1.27) and poor self-rated health (OR=1.13, 95% CI, 1.14–1.55) among shift workers compared to non-shift workers. There was a significant increased risk of cardiovascular disease, obesity, and diabetes among shift workers despite higher levels of physical activity and lower levels of sedentary behaviour compared to matched controls. Shift workers were 17% more likely to be obese (95% CI 7–27) and 27% more likely to have diabetes (95% CI 8–51).

Conclusions Shift work is associated with cardiometabolic health and mental health, as well as depression. The association between shift work and cardiometabolic health was independent of body mass index for cardiovascular disease and diabetes, and independent of fat mass index for diabetes. Subsequently, shift workers have an increased risk of developing other chronic disease.