• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.2
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• pp.138-148
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• 2017

Objectives: Sleep quality is directly related to the health, quality of life and working capacity and is affected by age, gender, exercise, life habits. Gender dissimilarities in sleep quality are acknowledged. However, the gender difference in the quality of sleep in shift workers was not well known. Our aim was to study the less known gender differences in the quality of sleep of shift workers. Methods: 1,008 study subjects aged between 21 and 57 years among these, 637(525 male and 112 female workers) were daytime workers and 371(253 males and 118 female workers) were shift workers. Sleep quality was measured by self-report through the Pittsburg Sleep Quality Index(PSQI) and fatigue was measured by using the Chalder Fatigue Scale(CFS). All data was analyzed using SPSS version 19.0 program. The study was approved by the Institutional Review Board of the Occupational Safety and Health Research Institute. Results: Overall, sleep quality was found to be worse in shift workers than in daytime workers and in female than in male. Fatigue in shift female workers was significantly higher than in daytime female workers and shift male workers. In Spearman correlation analysis results, fatigue were significantly associated with gender, drink habit, regular exercise, working hours and sleep quality. With group male workers as the reference, the odds ratio(OR) for having a CFS was 2.115(${\beta}$ value=0.749, p<0.01), and subjective sleep quality, sleep latency, daytime dysfunction and PSQI were 1.541(${\beta}$ value=0.432, p<0.05), 2.297(${\beta}$ value=0.831, p<0.001), 1.798(${\beta}$ value=0.587, p<0.01) and 2.224(${\beta}$ value=0.799, p<0.01), respectively. Conclusions: Shift work played an important role in lowering the quality of sleep, and the effect was more pronounced in female workers than in male workers. Sleep quality was related to fatigue, especially sleep quality, sleep duration, sleep disturbances and daytime dysfunction were significantly related. Therefore, to improve fatigue and sleep quality of shift worker, it is necessary to improve healthy habits such as regular exercise, smoking cessation, and limited drinking. In particular, it is urgent to develop and implement a regular exercise program to reduce fatigue and improve the quality of sleep in workplace.

• Journal of Korean Biological Nursing Science
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• v.2 no.2
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• pp.81-89
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• 2000

To determine the optimal rotational shift system, the effect of the direction of the rotational work shifting on the nocturnal rhythm of plasma melatonin were investigated in nursing students. Two groups of nine volunteers participated as experimental subjects, and two nursing students participated as a control group. The directions of the rotational work shift were as follows: CW(clockwise)-shift were rotated in the direction of day shift(3 days), evening shift(3 days), off duty(1 day) and night shift(5 days), and CCW(conuterclockwise)-shift were done in the reverse direction. Plasma melatonin concentrations was measured by radioimmunoassay. The results were as follows : The plasma melatonin levels were kept low at night and in the following morning in the CW night shift workers, whereas the level started to increase at 05 : 00 hr in two workers of four CCW shift workers. These result suggests that the shift rotation in the CW direction is more acceptable in terms of the adaptation of hormonal rhythms. These results indicate that the CCW rotation of shift work is somewhat better than CCW rotation for the adaptation to shift work on hormonal aspects in nurses.

• Korean Journal of Occupational Health Nursing
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• v.33 no.1
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• pp.1-11
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• 2024

Purpose: This study aimed to analyze the factors influencing the well-being of middle-aged non-shift female workers using health-determinant models. Methods: This study analyzed data from the fifth Korean Working Conditions Survey (KWCS), involving 5,449 participants. A hierarchical multiple regression analysis was employed to examine the relationships between various factors and well-being. Results: The analysis identified key factors affecting well-being in middle-aged female non-shift workers, including supervisor support, presenteeism, satisfaction with the working environment, autonomy in working hours, support from coworkers, workplace discrimination, occupation, work-life balance, sleep problems, workplace size, weekly work hours, and sickness absence. This study confirms that the well-being of middle-aged non-shift female workers is influenced by factors at the individual, social, and community levels as well as by conditions related to love. Conclusion: To enhance the well-being of middle-aged female non-shift workers, it is essential to reinforce positive factors such as support from coworkers and superiors. Additionally, addressing and mitigating negatively influencing factors such as workplace discrimination and sleep problems is crucial in promoting well-being. By implementing measures to improve these aspects, organizations and policymakers can contribute to a healthier and more supportive work environment for middle-aged, non-shift female workers.

• Safety and Health at Work
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• v.11 no.2
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• pp.244-247
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• 2020

The occurrence of the shift work disorder (SWD) in health-care workers (HCWs) employed in 24/7 hospital wards is a major concern through the world. In accordance with literature, SWD is the most frequent work-related disturb in HCWs working on shift schedules including night shift. In agreement with the Luxembourg Declaration on workplace health promotion (WHP) in the European Union, a WHP program has been developed in a large Hospital, involving both individual-oriented and organizational-oriented measures, with the aim to prevent the occurrence of SWD in nurses working on shifts including night shift. The objective assessment of rotating shift work risk and the excessive sleepiness were detected before and after the implementation of the WHP program, by using the Rotating Shiftwork-questionnaire and the Epworth Sleepiness Scale. The findings of this study showed the effectiveness of the implemented WHP program in minimizing the impact of shift work on workers' health and in preventing the misalignment between sleep-wake rhythm and shift working.

• Annals of Occupational and Environmental Medicine
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• v.34
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• pp.33.1-33.13
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• 2022

Background: Circadian rhythm disturbance caused by shift work has adverse effects on the metabolic homeostasis of the liver. Disruption of the metabolic homeostasis of the liver causes fat accumulation in the liver. The aim of this study was to investigate the correlation between shift work and non-alcoholic fatty liver disease (NAFLD) among male workers in the steel manufacturing industry of Korea. Methods: Based on medical examination data collected in June 2020, 2,511 male subjects from one steel manufacturing company in Korea were selected in total. NAFLD was evaluated using abdominal ultrasound, which was performed by two experienced radiologists. The multinomial logistic regression analysis was performed by adjusting for age, physical activity, smoking history, alcohol consumption, body mass index, waist circumference, blood pressure, blood glucose, lipidemia, liver function test, employment duration, and hepatotoxic materials exposure status. Results: Compared to daytime workers, the odds ratio (OR) of moderate-severe NAFLD in shift workers was 1.449 (95% confidence interval [CI], 1.028-2.043). Compared to daytime workers, the ORs of moderate-severe NAFLD were significantly higher for the group that engaged in total shift work for more than 20 years (OR, 2.285; 95% CI, 1.051-4.970), the group that was not allowed to sleep during night shift work (OR, 1.463; 95% CI, 1.030-2.078), and the group that consumed food during night shift work (OR, 1.580; 95% CI, 1.093-2.284). Conclusions: There was a correlation between shift work and moderate-severe NAFLD in male steel manufacturing workers. There will be a need for more research related to the correlation of shift work with steatohepatitis and cirrhosis in the future.

• Korean journal of aerospace and environmental medicine
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• v.30 no.2
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• pp.61-65
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• 2020

In the case of aviation maintenance work, several kinds of shift works are performed during day and night, and a lot of works are performed on the ramp due to the characteristics of the aircraft flight schedule. Maintenance workers are often exposed to the sun or in cold temperatures for aircraft maintenance works. The fatigue risk of the maintenance workers will be weighted. In particular, the work at night shift under normal biological rhythms can make maintenance workers feel sleepy during daytime work. It can also affect the safety of aircraft and individual workers. Accordingly, this study will consider fatigue-related previous researches in the field of aviation maintenance, review the effects of shift work, and how fatigue affects aviation mechanics during the day/night shifts. Considering these factors, we tried to present a plan that can minimize the fatigue of aviation workers through this study.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.4
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• pp.550-561
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• 2019

Objectives: The purpose of this study is to provide basic data for the improvement of the working environment for health prevention and related countermeasures for shift workers. This study was conducted based on the Fifth Korean Working Conditions Survey (KWCS), which analyzed the health effects of shift work forces and compared them with preceding studies. Methods: By analyzing secondary rates using raw data from the 5th KWCS, 4,870 (9.7%) of the 50,184 total study subjects were divided into shift work and 45,314 (90.3%) non-shift work groups based on the response to shift status. Variables that could affect work health issues were identified and corrected. A cross-analysis was conducted to examine demographic characteristics (gender, age, and education level) of the workers and occupation characteristics (monthly net earnings, employment type, occupation, working period up to now, workplace scale, type of work system, and weekly working hours). In order to find the work health issue ratio between the shift and non-shift work groups, logistic regression was analyzed and the association with health problems according to shift type by gender was looked at through cross-analysis. Results: According to the surveys conducted from the 1st KWCS (2006) to the 5th KWCS (2017), the proportion of shift workers continued to increase. Also, muscular pains in the lower limbs (hips, legs, knees, feet, etc.) (OR=1.135, 95%CI 1.031-1.251), headaches, eyestrain (OR=1.580, 95% CI 1.428-1.748), anxiety (OR=1.715, 95% CI 1.402-2.099), difficulty falling asleep (OR=1.391), and other problems (OR=7.392) were reported. In addition, back pain, muscular pains in shoulders, neck and/or upper limbs, muscular pains in lower limbs (hips, legs, knees, feet, etc.), headaches, eyestrain, depression, anxiety, overall fatigue resulted in significant results for both male and female shift workers. Depression and anxiety were higher in female shift/circulation compared to males. Conclusions: The social nets for the health and safety of shift workers should be explored in a variety of ways, including management and supervision of shift sites, attempts to reorganize and improve the shift system, development of workers' health recovery programs, promotion, systematic treatment, and compensation systems.

• Journal of Preventive Medicine and Public Health
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• v.25 no.4 s.40
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• pp.374-385
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• 1992

Some circadian rhythms can become disorgnized due to rotating shift work. This lack of organization, termed desynchronization, can produce a group of symptoms such as insomnia, GI disturbance and fatigue among many rotating shift workers. The magnitude of these symptoms are influenced by personal and environmental factors and the patterns of shift work. This study was carried out to investigate the subjective symptoms related to rotational schedules of shift work after personal and environmental factors adjusted. 182 male workers in rapidly rotating shift system and 86 male workers in weekly rotating shift system were conducted the questionnaire on personal factors and subjective sleep, GI and fatigue symptoms. Major findings obtained from this study are as follows: 1. The symptoms of 'feeling tired at work' and 'being irritable' were more frequent in weekly rotating shift workers (P<0.05), and the mean of symptom score was significantly higher in weekly rotating shift workers(P<0.01). 2. According to 6 hours of sleeping which is a definite elevation point of fatigue, there was not a significant difference between two groups in sleeping hours. Among workers in rapidly rotating shift system, the mean of symptom score was significatly higher in workers of less than 6 hours of sleeping(P<0.05), but it was not different among weekly rotating shift workers. 3. The symptoms of GI disturbance were more frequent in weekly rotating shift workers but statistically not significant. 4. The positive rate of mental and physical fatigue symptoms were significantly higher in weekly rotating shift workers(P<0.01) and mental and physical fatigue symptoms were more frequent in them (P<0.01). 5. After the effect of the factors that were significantly different between two groups by $X^2-test$ were controlled, the mean score of sleep disturbance was significantly higher in weekly rotating shift workers (P<0.01) and mental physical fatigue symptoms were more frequent in them (P<0.01). Based on these study results, subjective symptoms were more common in the weekly rotating shift workers. In future, medical examination and laboratory test will be also administered to evaluate a more accurate health outcomes and the review of current shift schedules will be required.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.4
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• pp.517-529
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• 2019

Introduction: Although shift work is an inevitable form of labor in modern society, it has been identified as a cause of many ailments, such as cancer and musculoskeletal disorders. Meanwhile, previous studies have also shown that musculoskeletal disorders account for a large proportion of total industrial accidents and a high prevalence rate of these ailments has been found in shift workers. Methods: Among the respondents to the 5th Korea Working Conditions Survey(KWCS) 3,916 shift workers(2,658 of whom have not experienced musculoskeletal pain and 1,258 who have experienced musculoskeletal pain) were asked how the work regularity of shift workers affected musculoskeletal pain. Results: The results of a dichotomous logistic regression by correcting the demographic characteristics of the study subjects showed a lower prevalence of musculoskeletal pain in the 'High' regularity group compared to the 'Intermediate' regularity group for the criterion 'Regularity of Time Fixation'. A lower prevalence of musculoskeletal pain was shown in the 'High' and 'Moderate' regularity group compared to the 'Very Low' regularity one. Conclusions: Based on these findings, it was found that musculoskeletal pain occurs less when the work regularity of shift workers is 'Very high' or 'Intermediate', and the effect of working regularity on musculoskeletal pain varies for each shift type of work. It is deemed that more precise observation and understanding are required when managing the working environment of shift workers, and further study of regarding this issue is needed.

• 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.