• Journal of Korean Institute of Industrial Engineers
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• v.30 no.3
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• pp.181-189
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• 2004

The purpose of this study was to investigate the effects of sleep/wake behavior for shift workers in the iron and steel industry using wrist actigraph for 59 male workers on a continuous full-day three-team three-shift system of backward rotation including on-duty and off-duty periods. The wrist actigraph data were recorded for 15 days (l shift cycle) for each subject. The sleep length at home during night shift decreased significantly as compared to the morning or evening shifts. The night shift nap length increased significantly in all sections as compared to the morning or evening shifts. The nap length in the Steel Manufacturing Process and Rolling Process during night shift decreased significantly as compared to the Machine Maintenance Section, the Forwarding of Products Section, and the Field Management Section. However, the sleep length at home while off-duty period increased significantly. The percentage of nap length during night shift in the Rolling Process, Steel Manufacture Process, and the other three types of jobs was 16.0%, 20.4%, and about 50.0%, respectively. The nap length during night shift for the above 50 year olds increased significantly as compared to the below 50 year olds. Finally, we discussed the role of nap-taking during the burden on night shift workers and the increased difficulty in continuing their job.

• Sleep Medicine and Psychophysiology
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• v.2 no.2
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• pp.171-179
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• 1995

Objectives : This study was carried out to determine whether the state anxiety may affect sleep on the night before surgery. Methods : The researcher examined the clinical charts of patients who were scheduled to receive surgery by general anesthesia the following day and then had semistructural interview with patients. In addition Spielberger's State Anxiety Inventory(1972), presleep questionnaire and postsleep questionnaire were administered to the patients. One hundred patients who responded to the questions were divided into three groups based on the state anxiety scores; low(n=35), middle(n=27) and high(n=38). Demographic and clinical characteristics of patients, some possible factors affecting sleep, daytime status and nighttime sleep before surgery were compared among three groups. Results : 1) There was no significant difference in demographic characteristics and some possible factors affecting sleep on the night before surgery among three groups. 2) In terms of clinical characteristics, the expectancy of surgical result was significantly different among three groups. More patients in low anxiety group than in middle and high anxiety groups, predicted surgical results as good, while more patients in middle and high anxiety groups than in low anxiety group could not predict their surgical results. 3) For daytime status, high anxiety group felt more tired compared to low anxiety group, but there was no significant difference in daytime nap among three groups. 4) For nighttime sleep before surgery, high anxiety group expected poor sleep and in fact, waked more frequently during sleep than low anxiety group. However there was no difference in bed time, sleep latency, rise time, total sleep time, sleep depth and sleep quality among three groups. 5) The need for hypnotics was higher before bedtime and also after rise in high anxiety group compared to low anxiety group. Conclusions : These results indicate that the individuals with high state anxiety before surgery have poor sleep and furthermore suggest that anxiolytics and/or hypnotics may be required to decrease anxiety and improve sleep for those with high state anxiety.