Approximately 20% of the American, European, and Australian working population is employed in shift work, working in alternating and rotating morning, afternoon, and night shifts. Such work patterns disrupt the sleep-wake cycle and can affect physical and mental health.

A recent meta-analysis assessed the pooled effects of shift work on mental health and whether this differed among men and women. Included in the analysis were data from seven prospective cohort studies with 28,431 participants that examined the association of shift work exposure with adverse mental health outcomes.

The researchers found that shift workers had an increased risk of adverse mental health outcomes compared with workers who didn't work such shifts. Specifically, shift work was associated with a 33% greater risk of depressive symptoms. The risks of anxiety and other symptoms of poor mental health were also greater in shift workers, but the differences weren't statistically significant. Female shift workers were more likely than women who didn't work such shifts to experience depressive symptoms, a difference that was not seen among men.

The authors note that they conducted sensitivity analyses on the effects of gender but couldn't do so for other personality traits or job-related factors, because this information wasn't available in the included studies. Workplace health promotion programs and policies are needed to minimize shift workers' risk of poor mental health, they advise.