Association between sleep quality and type of shift work in Korean firefighters

BACKGROUND: Shift work that interferes with normal sleep patterns, is known to be a cause of sleep disturbance and has been studied through various occupational groups. However, it is not known which shift type is better for sleep health. METHODS: This study included 568 firefighters. Sleep quality was evaluated using Pittsburgh Sleep Quality Index. Sleep quality was categorized into 2 groups; good quality (≤ 5 points) and poor quality (≥ 6 points). Demographic variables, depression, anxiety, type of shift, and job were collected by self-reported questionnaires. The χ(2) test, t-test, and multiple logistic regression analysis were used to evaluate the effect of shift type on the sleep quality of firefighters. RESULTS: Three hundred thirty-seven firefighters (59.3%) have poor sleep quality. Compared to day workers, the odds ratios (ORs) of poor sleep quality were 2.169 (95% confidence interval: 1.137–4.134) in 6-day cycle, 2.161 (1.150–4.062) in 9-day cycle, 1.805 (1.087–2.997) in 21-day cycle, and 1.485 (0.718–3.069) in 3-day cycle. The ORs of poor sleep quality were 1.697(1.021–2.823) in fire suppression and 2.325 (1.213–4.455) in emergency medical service compared to administration. CONCLUSIONS: All shift work type except for the 3-day cycle was associated with poor sleep quality compared to day work.