The Effect of Morningness-Eveningness on Shift Work Nurses: Sleep Quality, Depressive Symptoms and Occupational Stress

Abstract

Introduction: Morningness-Eveningness indicates that an individual has a preference in diurnal performance, sleep-wake cycle for activity and alertness during the day. The purpose of this study was to investigate the effect of morningness-eveningness type and shift work duration on nurses relative to sleep quality, depressive symptoms and occupational stress. Material(s) and Method(s): Data was collected using self-administering questionnaires by 257 three eight-hour randomly rotating shift system nurses at St. Vincent's hospital. Questionnaires were composed of baseline demographic data, Korean version of Morningness-Eveningness Questionnaire, Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Beck Depression Inventory and Korean Occupational Stress Scale. Kruskal- Wallis H test and analysis of covariance (ANCOVA) were used to identify significant differences in sleep parameters, depressive symptoms and occupational stress according to morningness-eveningness type. Result(s): There was significant difference in Subjective Sleep Quality score (p=0.018). Post hoc analysis revealed differences between eveningness vs. morningness (p=0.001) in Subjective Sleep Quality score. There were tendencies in sleep efficiency, PSQI total score and ESS between morningness- eveningness type. However, there were no significant differences in total sleep time, depressive symptoms and occupational stress including eight sub-categories according to morningness-eveningness type. Morningness- Eveningness score revealed negative correlation with Subjective Sleep Quality score and Total score of PSQI and ESS, and positive correlation with sleep efficiency. Shift work duration showed positive correlation with total stress and stress due to job demand. Conclusion(s): Eveningness type nurses revealed lower Subjective Sleep Quality and tendency for poor sleep efficiency, poor overall sleep efficiency and more severe daytime sleepiness than other type. Morningness type might have positive effects on sleep quality and daytime sleepiness. However, morningness-eveningness were not decisive factors for total sleep time, depressive symptoms and occupational stress. Longer shift work duration had correlation with higher occupational stress. Short-term medication, workers' chronotypes consideration and naps before night shifts may be helpful in improving mental health and quality of life for shift nurses, especially for evening shifts.