The common idea that shift workers can adjust to their working times has been challenged by a recent publication in eBioMedicine. According to the findings of the study, those working a night shift have their sleep quality and circadian rhythms significantly disrupted, even if they are longtime night shift workers.
The study followed 63 night shift workers and 77 day shift workers for one week. All participants were nurses or nurse assistants at a hospital in France, and all had been working either night or day shifts for a minimum of five years. The participants wore accelerometers and chest temperature sensors throughout the study, which allowed the researchers to measure their movements and estimate sleep duration, regularity of circadian rhythms, and sleep disruptions in both groups.
The results showed that those working night shifts had less than half the median sleep quality and sleep regularity of those working day shifts. Additionally, 48% of the night shift workers had a disrupted circadian rhythm. Participants also took a survey to measure their chronotype, or preferred sleep and wake times, and night shift workers’ sleep times tended not to line up with their chronotype. Even night shift workers who had been on night shifts for many years showed disruptions in their sleep quality and circadian rhythms, and more years spent working night shifts corresponded with greater circadian rhythm disruptions.
Previous research has linked disrupted circadian rhythms to increased risks of cardiovascular disease, cancer, and other long-term health issues. As one of the study’s authors noted, these results show that night shift work can pose serious health risks, even though many people see it as merely an inconvenience.