ABSTRACT
OBJECTIVES: To investigate sleep-wake patterns and chronotype in rapidly rotating shift nurses (SRN). METHODS: We translated and back-translated the Korean Munich ChronoType for Shift-Workers (K-MCTQ(shift)) with original authors' permission. In this study, 353 full-time, SRN (age 28.7±3.95 years 341 females, mean shift–working duration=5 years 9 months) at one university hospital completed the K-MCTQ(shift) and the Morningness-Eveningness Questionnaire (MEQ). Time in bed, sleep duration, and mid-sleep time (sleep onset time+1/2 sleep duration) were evaluated on work days and free days. Social jet lag was computed for each shift. Chronotype was assessed based on the mid-sleep time on free days corrected for sleep debt accumulated over the workweek (MSF(SC)). RESULTS: Sleep duration on workdays were 5.2 hours (day shift, D), 7.7 hours (evening shift, E), and 5.7 hours (night shift, N), respectively. Alarm clock usage on workdays was the highest in day-shifts (92.4%). The chronotype of 166 SRN who did not use alarm on free days was 6:09 h. Social jet lag was the longest in day-shifts (3.3 hours), and the shortest in evening-shifts (0.3 hour). Mid-sleep after the evening-shift (MSW(E), MSF(E), MSF(E)(SC)) showed significant correlations with MEQ scores. CONCLUSIONS: The Korean MCTQ(shift) provides actual sleep-wake patterns per shift schedule and chronotype in shift workers. We suggest that the sleep-corrected version of mid-sleep on free days after evening shifts (MSF(E)(SC)) is suitable for assessing chronotype in shift workers.
Subject(s)
Female , Humans , Appointments and SchedulesABSTRACT
OBJECTIVES: The aim of our study was to compare sleep wake patterns and nocturnal sleep parameters between the morning type (MT) and evening type (ET). METHODS: The Morningness-Eveningness Questionnaire, Pittsburgh Sleep Quality Index (PSQI), and Korean version of the Epworth Sleepiness Scale (KESS) were administered to subjects recruited among visitors to the Chuncheon National Museum from 2010 to 2011. Actigraphy data (Actiwatch-2, Philips-Respironics Co.) were collected from eight MT (Age 38.0+/-3.8, M : F=2 : 6), 12 neither type (NT) (Age 34.2+/-5.1, M : F=2 : 10), and nine ET (Age 30.3+/-6.8, M : F=2 : 7) subjects. RESULTS: Scores for PSQI and KESS did not differ significantly among the MT, NT, and ET groups. No differences in time in bed, total sleep time, sleep efficiency, wake after sleep onset, sleep latency, and fragmentation index were observed among the three groups. In the ET group, the mean wake time on free days was significantly later, and the mean sleep duration on free days was significantly longer, compared with those of the MT group (p<0.01). CONCLUSION: No differences in sleep quality, daytime sleepiness, and nocturnal sleep parameters were observed among the MT, NT, and ET groups. Compared to MT subjects, ET subjects showed later wake time and longer sleep duration on free days.