Shift and Night Work and Mortality: Prospective Cohort Study
Summary
This prospective cohort study followed over 1.5 million French employees from 1976 to 2002 using employment records and a job-exposure matrix to classify shift and night work. Mortality was tracked through the national registry, covering both overall deaths and specific causes. Over the 26 years of follow-up, more than 22,000 deaths occurred. The study found that shift and night workers had higher risks of all-cause mortality and several cause-specific deaths. In men, these included cardiovascular disease, cancer, smoking-related illness, and suicide. In women, shift work was associated with all-cause, cancer, and preventable mortality, with additional risks for suicide and breast cancer after long-term night work. The results showed dose–response patterns, meaning risks increased with more years of night-shift exposure.
Why It Matters For Night Shift Workers and Night Owls
For night-shift workers, this large national study underscores that health risks accumulate over years of exposure. The findings link prolonged night or rotating work to higher chances of dying from cardiovascular disease, certain cancers, and suicide, with some differences between men and women. While the study didn’t test prevention strategies, its message is clear: the structure and length of night-shift exposure matter for long-term survival. For individuals, it reinforces the need for regular health monitoring. For workplaces, it highlights the importance of limiting prolonged night duty and ensuring adequate recovery to protect staff health over a career.
Notes
Open access.