Predictors of shift work disorder among nurses : a longitudinal study

Background: Shift work is associated with sleep problems and impaired health. The main aim of the present study was to explore predictors of developing shift work disorder (SWD) among Norwegian nurses using a longitudinal design. Methods: A total of 1533 nurses participating in a survey on shift work, sleep and health responded to questionnaires at baseline and at follow-up about two years later. SWD was defined as problems of excessive sleepiness and/or complaints of insomnia related to the work schedule. Results and Conclusions: There was a significant reduction (p < 0.001) in the prevalence of SWD from baseline to follow-up, from 35.7% to 28.6%. Logistic regression analyses showed significant risks of having SWD at follow-up and the following variables measured at baseline: number of nights worked the last year (OR = 1.01, 95% CI = 1.01–1.02), having SWD (OR = 5.19, 95% CI = 3.74–7.20), composite score on the Epworth Sleepiness Scale (OR = 1.08, 95% CI = 1.04–1.13), use of melatonin (OR = 4.20, 95% CI = 1.33–13.33), use of bright light therapy (OR = 3.10, 95% CI 1.14–8.39), and symptoms of depression measured by the Hospital Anxiety and Depression Scale (OR = 1.07, 95% CI = 1.00–1.14). In addition, leaving night work between baseline and follow-up was associated with a significantly reduced risk of SWD atfollow-up (OR = 0.12, 95% CI = 0.07–0.22).