0700 DIFFERENTIAL EFFECTS OF CIRCADIAN TYPOLOGY ON SLEEP, FATIGUE, MOOD, AND QUALITY OF LIFE

Abstract

Introduction: Effects of circadian typology (CT) on various psychological and physiological conditions have been controversial. We aimed to investigate the association between CT and sleep, mood, and quality of life (QOL) after controlling for possible confounding factors, and to assess how the effect of CT differs depending on the variables in employees of a university hospital. Methods: The present study included a total of 1807 participants, who consisted of nurses, technicians, other paramedics, and office workers. The response rate was 80.2%. Data on demographic variables, lifestyle, engaging shift work, sleep quality, sleepiness, fatigue, mood, quality of life, morningness-eveningness and resilience were obtained and compared according to the circadian typology. Stepwise regression analyses were performed to assess the role of contributing variables including morningness-eveningness on sleep quality, sleepiness, fatigue, mood and QOL. Results: The mean age of the participants was 29.8 years, 86.3% of them were female and 53.0% were shift workers. With respect to CT, 7.6% the participants reported themselves as morning-types, 61.1% reported themselves as neither-types, and 31.3% replied that they were evening-types. Subjects with evening-type showed greater disturbances in sleep quality, sleepiness, fatigue, mood, and QOL than neither- types and morning-types. In the regression analysis, CT explained a much less portion of the total variance for fatigue, depression, and QOL than resilience did. Resilience was found to be a powerful predictor of all the variables measured. Conclusion: We found a differential effect of CT on sleep quality, daytime sleepiness, fatigue, mood, and QOL. Sleep directly reflects an individual's intrinsic circadian rhythm, but other physical and psychological functions interact with CT in a more complex way. Given the robust association of resilience with fatigue, mood, and QOL, resilience- promoting programs can be considered helpful in overcoming the undesirable effect of CT.