J Prev Med Public Health.  2021 Jan;54(1):46-54. 10.3961/jpmph.20.555.

Relationship Between Shift Intensity and Insomnia Among Hospital Nurses in Korea: A Cross-sectional Study

  • 1Department of Preventive Medicine, Graduate School of Public Health, Seoul National University, Seoul, Korea
  • 2Department of Occupational and Environmental Medicine, Ewha Womans University Mokdong Hospital, Seoul, Korea
  • 3Department of Occupational and Environmental Medicine, International St. Mary’s Hospital, Incheon, Korea
  • 4Department of Statistics, Dongguk University, Seoul, Korea
  • 5Ewha Medical Research Institute, Ewha Womans University School of Medicine, Seoul, Korea


This study explored the relationship between shift intensity and insomnia among hospital nurses.
The participants were 386 female hospital nurses who underwent a special health examination for night workers in 2015. The Korean Insomnia Severity Index (ISI), indices of shift work intensity, and other covariates such as amount of exercise, level of alcohol consumption, employment duration, and hours worked were extracted from the health examination data. The indices for shift intensity were (1) number of 3 consecutive night shifts and (2) number of short recovery periods after a previous shift, both assessed over the prior 3 months. Multiple logistic regression analysis adjusted for the aforementioned covariates was performed to evaluate the association of shift intensity with insomnia, defined as an ISI score of ≥8.
The nurses with insomnia tended to be younger (p=0.029), to have worked 3 consecutive night shifts more frequently (p<0.001), to have experienced a greater number of short recovery periods after the previous shift (p=0.021), and to have worked for more hours (p=0.006) than the nurses without insomnia. Among the other variables, no statistically significant differences between groups were observed. Experiences of 3 or more consecutive night shifts (odds ratio [OR], 2.33; 95% confidence interval [CI], 1.29 to 4.20) and 3 or more short recovery periods (OR, 2.01; 95% CI, 1.08 to 3.73) were associated with increased odds of insomnia.
The results suggest that decreasing the shift intensity may reduce insomnia among hospital nurses working rotating shifts.


Nurses; Shift work; Night work; Insomnia; Shift intensity
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