Sleep Patterns, Daytime Sleepiness and Personality Factors in Rotating Shiftworkers

Kim, H; Kim, L; Suh, K Y

Abstract

OBJECTIVES
This study was to evaluate sleep patterns and daytime sleepiness resulting from shiftwork. The authors, also, tried to find out the relationship between the severity of daytime sleepiness and personality factors.
METHODS
The subjects consisted of 41 female rotating shiftwork nurses and the control group consisted of 39 female daytime-workers. All of them completed the Sleep questionnaire of Korea University Sleep Disorder Clinic, the Epworth Sleepiness Scale(ESS), the 16 Personality Factors(16PF), the Beck Depression Inventory(BDI) and the State Trait Anxiety Inventory(STAI). Multiple regression analysis of 16PF of the rotating shiftwork nurses was done to fine out possible predictors of the severity of daytime sleepiness.
RESULTS
The mean duration of deprived sleep due to rotating shiftwork was 64.26+/-14.54 min. The frequency of sleep difficulty(1.24+/-1.17 day/week vs 0.67+/-1.31 day/week, p<0.05), time needed to fall asleep(103.05+/-73.48 min. vs 70.00+/-60.08 min., p<0.05), sleep duration when having some difficulties in sleep(204.25+/-79.90 min., vs 280.44+/-111.59 min., p<0.001), recent changes in energy(x2=4.16, p<0.05), worrying about sleep(x2=11/08, p<0.05), and taking naps(x2=4.98, p<0.05) showed significant differences between rotating shiftworkers and normal controls. The ESS score of shiftworkers(8.68+/-3.04) was greater than that of normal controls(6.86+/-3.04)(p<0.01). Personality factors such as C factor(R2=0.283), I factor(R2=0.358) and G factor(R2=0.470) were related with the severity of the daytime sleepiness(p<0.001).
CONCLUSIONS
The rotating shiftwork nurses had more difficulties in sleep such as having difficulties in falling asleep and in maintaining sleep, and showed lowered energy, decreased senses of well-being and so on. The rotating shiftwork nurses experienced more severe daytime sleepiness than controls did. Personality factors, such as C factor, I factor, and G factor of 16PF were suggested to be useful for predicting the severity of daytime sleepiness resulting from rotating shiftwork.