Hospital Night Shift Workers Experience Poorer Sleep Quality and Circadian Rhythms


A study conducted via telemonitoring showed that hospital workers who performed night shifts had significant negative impacts on their sleep quality and circadian rhythms.

 Bärbel Finkenstädt, PhD, professor, Department of Statistics, University of Warwick

Bärbel Finkenstädt, PhD

In a recent cross-sectional telemonitoring study, the findings displayed a risk of poorer health in night shift workers for their circadian and sleep rhythm markers, tracked with a wearable device.1 This study supports the use of telemonitoring for circadian and sleep cycles as it could be a personalized prevention method for shift workers who could be at increased risk of poor health.

From the total number of participants (n = 140; women, n =133), 63 were night shift workers (NS) and 77 were day shift workers (DS). The NS group had a worse median rest-activity Rhythm Index (0.38 [IQR, 0.29-0.47] vs. 0.69 [0.60-0.77]; P <.0001) and rest quality p1-1 (0.94 [0.94-0.95] vs 0.96 [0.94-0.97]; P <.0001) during the study week period even though both groups had similar median amounts of rest.1

In comparison with 70% of the DS group (P = .026), 48% of the NS group showed a circadian period in temperature.1 For both workdays (P <.0001) and days off (P = .0098), poor rest quality p1-1 was associated with nightshift work. Even years of past night shifts exposure indicated poor rest-activity Rhythm Index on workdays (P = .0074), and on days the workers are free (P = .0005).

Cosupervisor of the study, Bärbel Finkenstädt, PhD, professor, Department of Statistics, University of Warwick, said in a statement, "There's still an assumption that if you do night work, you adjust at some stage. But you don't. We saw that most workers compensate in terms of quantity of sleep, but not in terms of quality during the work time."2

The study telemonitored circadian rhythmicity in activity, sleep, and temperature for 1 week during work as well as days the participants had free time. The participants wore a Bluetooth low energy thoracic accelerometry and temperature sensor which was wirelessly connected to a GPRS gateway and a hub server for health data.1 A multivariate analyses was used to compare parameters and identified predictors of circadian and sleep disruption.

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"I think there's a misunderstanding that night shift work is just an inconvenience, whereas it can be linked to serious health risks. We can't avoid shift work for many professions, like healthcare workers, so we should be thinking about what can be done in terms of real-world adjustments to improve working conditions and schedules of shift workers. A better understanding of the biological mechanisms helps to find answers to this question,” cosupervisor, Julia Brettschneider, PhD, Department of Statistics, University of Warwick, said in a statement.2

The limitations of this study comprised of a lack of medical follow-up and lack of a confirmatory session during the single week the study was held. Although the study’s sample had a small number of men, the number of men in the groups were consistent during the day shift and as in the night shift. Another limitation was that the study did not involve participants who had an intolerance with night shifts.

"Nearly 20% of the night workers could not even adjust their circadian rhythms during their free time, with the severity of impairment tending to increase with the number of years of night work. The telemonitoring technology, and analysis methods we have set up make it now possible to objectively evaluate circadian and sleep health in night workers in near real time, and design prevention measures for individual workers whenever necessary,” cosupervisor, Francis Lévi, MD, research director, Université Paris-Saclay, added further in the statement.2

Studies in future research should look at the relations between digital circadian and sleep health in the context of prior exposure to night work. Factors to investigate further in this field include men who worked in the night or day shift and compare their results from the start of their employment.1 Other future studies could explore more of the long-term outcomes with night shift workers, specifically with particular diseases, such as cancer, that may be linked to the disruption of workers’ circadian clock.2

1. Zhang Y, Cordina-Duverger E, Komarzynski S, et al. Digital circadian and sleep health in individual hospital shift workers: A cross sectional telemonitoring study. EBioMedicine. 2022;81:104121. doi:10.1016/j.ebiom.2022.104121
2. University of Warwick. Shift workers 'can't all adjust to a night shift'. ScienceDaily. July 20, 2022. Accessed October 13, 2022.
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