Objective. This study aimed to understand the prevalence of sleep disorders among shift workers and analyze the relationship between sleep disorders and shift work. Methods. Baseline data were collected from subjects who were then followed for 2 years in a prospective cohort study. The cohort ultimately included 2453 people starting in May 2013, and follow-up with questionnaires was performed in July 2014 and October 2015. Sleep disorders were assessed with the Pittsburgh sleep quality index. Results. The risk of sleep disorders among two-shift workers (relative risk [RR] = 1.318, 95% confidence interval [CI] [1.025, 1.695]), three-shift workers (RR = 1.326, 95% CI [1.048, 1.679]) and four-shift workers (RR = 1.334, 95% CI [1.062, 1.675]) was higher than that among non-shift workers, and an increasing trend was observed in sleep disorders as the number of shifts increased. Conclusions. Shift workers have a higher incidence of sleep disorders than non-shift workers. An increasing linear trend was observed between the number of shifts and sleep disorders. In the petroleum industry, it is necessary to decrease the frequency of shifts to reduce the incidence of sleep disorders among shift workers.
Keywords: cohort study; shift work; sleep disorders.