• Safety and Health at Work
• /
• v.9 no.2
• /
• pp.203-209
• /
• 2018

Background: Night shift work is associated with many problems such as sleep deprivation, sleepiness, decreased cognitive performance, increased human errors, and fatigue. This study set out to measure cognitive performance, melatonin rhythms, and sleep after different consecutive night shifts (7 vs. 4) among control room operators (CORs). Methods: The participants included 60 CORs with a mean age of 30.2 years (standard deviation, 2.0) from a petrochemical complex located in Southern Iran. Cognitive performance was assessed using the n-back task and continuous performance test. To evaluate melatonin, saliva was collected and tested by enzyme-linked immunosorbent assay. To assess sleep and sleepiness, the Pittsburgh Sleep Quality Index and Karolinska Sleepiness Scale were used, respectively. Results: Individuals who worked 7 consecutive night shifts had a significantly better cognitive performance and sleep quality than those who worked 4 consecutive night shifts. However, salivary melatonin profile and sleepiness trend were not affected by shift type. Conclusion: The main duty of CORs working night shifts at the studied industry included managing safety-critical processes through complex displays; a responsibility that demands good cognitive performance and alertness. It is suggested that an appropriate number of consecutive night shifts in a rotating shift system should be planned with the ultimate aim of improving CROs performance/alertness and enhancing safety.

• Journal of muscle and joint health
• /
• v.21 no.2
• /
• pp.135-144
• /
• 2014

Purpose: The purpose of this study was to analyze and clarify the concept of shift work maladaptation syndrome and to facilitate development of interventions for the shift work adaptation. Methods: This study used Walker and Avant's concept analysis process. Results: Shift work maladaptation syndrome can be defined as the following attributes: 1) destruction of the circadian rhythm, 2) existence of a threshold, 3) individual characteristics (year of career, type of personality, and type of coping) 4) somatization, and 5) negative emotional conditions. The antecedents of shift work maladaptation syndrome consist of counterclockwise shift work, irregular shift cycle, night work which is breaking circadian rhythm, and lifestyle changing. The consequences as a result of shift work maladaptation syndrome are deterioration of health (gastrointestinal, neuro-psychic, cardiovascular function), reduction of social relationships, and turnover or resign. Conclusion: The results of this study can be useful as the foundation of shift work adaptation implementation.

• Sleep Medicine and Psychophysiology
• /
• v.9 no.1
• /
• pp.41-47
• /
• 2002

Objectives: In a number of simulated night shift studies, timed exposure to bright light improves sleep quality and work performance. We evaluated the effect of bright light on adaptation to night shift work with a field study. Methods: Five female nurses working shifts at Korea University Hospital were recruited for participation in this study. We investigated two series of six consecutive shift rotations comprising three day and three night shifts, using wrist Actigraphy, the Stanford Sleepiness Scale, Visual-analogue scales, STIM and tympanic membrane temperature for daytime sleep quality, alertness, subjective feeling, attention performance, and temperature rhythm. The subjects were exposed to bright light (2,500 lux) from 24:00 to 04:00 a.m. on three consecutive night shifts during the second series, whereas they worked under normal lightening (650 lux) conditions during the first series. Results: Actigraphic assessment of daytime sleep showed no significant difference between the first and third night shift in both baseline and light exposure phase. The mean lowest temperature shifted earlier during baseline phase but not during the light exposure phase. Also, the score for subjective feelings of depression, anxiety, physical discomfort and sleepiness was significantly higher in the third night shift than the first during baseline phase but not during the light exposure phase. Attention and attention switching ability was significantly improved in the third night shift compared to the first night during the light exposure phase but there were no significant changes during the baseline phase. Conclusion: This result suggests that there were no significant differences between the two phases in measures of quality of daytime sleep, but subjective feelings, attention and alertness were enhanced during light exposure. Although some placebo effects and learning effects might influence this result, bright light exposure between midnight and 4:00 a.m. may improve adaptation to night shift. In future, further controlled studies with a larger sample size, including melatonin measurement, are needed for real shift workers.

• Journal of the Korean Home Economics Association
• /
• v.27 no.1
• /
• pp.47-58
• /
• 1989

This study was undertaken to investigate whether the stress caused by day/night shifts on industrial workers can be affected through nutritional status. A sample of 573 female industrial workers, aged 17 through 23 years, from 4 different industries (2 in normal, 2 in 3 shift work pattern) were surveyed by questionaire examining their nutritional status, food intake, dietary habit, sleep complaint, performance of digestive organs, and degree of fatigue. Shift workers were surveyed during night work. The results are summarized as follows: 1. Sleep complaints and degree of fatigue in shift workers were higher than normal workers, whereas the performance of digestive organs were as lower than normal workers. These results showed that shift workers were more stressed than normal workers. 2. The workers who were surveyed were all poor in nutritional status. The intakes of calorie, protein, Ca, riboflavin, and ascorbic acid were lower than Korean Recommanded Dietary Allowences (RDA). Dietary habit of the shift workers was irregular. 3. There was a negative correlation between nutritional status and degrss of fatigue. The intakes of energy nutrients, ascorbic acid, and niain were significantly related to the degree of fatigue in which protein intake was found to be most influential. Among workers with the same level of protein intake, shift workers showed higher degree of fatigue. When the protein intake of shift workers was 100-125% of R.D.A., they showed the same degree of fatigue to the average normal workers.

• Journal of Korean Clinical Nursing Research
• /
• v.19 no.3
• /
• pp.333-344
• /
• 2013

Purpose: This study was conducted to provide baseline data to develop work patterns for nurses that are suitable to Korean hospitals. Shift work patterns and nurses' preferences for working condition were examined. Methods: Questionnaires for nurse departments and nurses were mailed to 478 hospitals from June 1 to July 30, 2012. Nurse departments of 174 hospitals and 1,409 nurses responded to the questionnaire. Data were analyzed using SPSS statistical program. Results: Of the nurses, 89.4% were working three shifts. Of the hospitals, 17.3% had implemented fixed night work. Although 80% of nurses preferred fixed time work, only 24.9% of hospitals had fixed working hours. Of the nurses, 57% agreed with night work as fixed but potential night nurses accounted for only 17% of the respondents. Sixty-three percent of the nurses agreed on short time work during busy hours. There were preference differences according to age, marital status and clinical career. Conclusion: As many nurses reported a preference for various flexible working patterns rather than three shift work, there is a need for new decisions on hospital policy to ensure improved working conditions for nurses and enhanced job security. Legal requirements also need to be considered for various work patterns.

• Annals of Occupational and Environmental Medicine
• /
• v.35
• /
• pp.22.1-22.9
• /
• 2023

Background: Shift work increases the risk of chronic diseases, including metabolic diseases. However, studies on the relationship between shift work and renal function are limited. The aim of this study was to investigate the association between shift work and a decreased glomerular filtration rate (GFR). Methods: Data were evaluated for 1,324,930 workers who visited the Korean Medical Institute from January 1, 2016 to December 31, 2020 and underwent a health checkup. Daytime workers were randomly extracted at a ratio of 1:4 after matching for age and sex. In total, 18,190 workers aged over 40 years were included in the analyses; these included 3,638 shift workers and 14,552 daytime workers. Participants were categorized into the shift work group when they underwent a specific health checkup for night shift work or indicated that they were shift workers in the questionnaire. The odds ratio was calculated using a conditional logistic regression to investigate the relevance of shift work for changes in GFR. Results: 35 workers in the shift group and 54 in the daytime group exhibited an estimated GFR (eGFR) value of < 60 mL/min/1.73m² (p < 0.01). The difference in eGFR values between two checkups differed significantly depending on the type of work (p < 0.01); the difference in the shift work group (-9.64 mL/min/1.73 m²) was larger than that in the daytime work group (-7.45 mL/min/1.73 m²). The odds ratio for eGFR reduction to < 60 mL/min/1.73 m² in the shift group versus the daytime group was 4.07 (95% confidence interval: 2.54-6.52), which was statistically significant. Conclusions: The results of this study suggest that eGFR decreases by a significantly larger value in shift workers than in daytime workers; thus, shift work could be a contributing factor for chronic kidney disease (CKD). Further prospective studies are necessary to validate this finding and identify measures to prevent CKD in shift workers.

• Korean Journal of Occupational Health Nursing
• /
• v.16 no.1
• /
• pp.37-47
• /
• 2007

Purpose: To find out the relationship between the shift work, and disrupted sleep and consequent fatigue symptoms. Methods: The questionnaires were given to 345 nurses of 4 hospitals with over 400 beds in Daejeon. Results: The shift workers showed worse subjective quality of sleep than the daytime workers, and had significantly higher frequency of "cannot get to sleep within 30 minutes", "wake up in the middle of the night" and "wake up in the early morning". The shift workers had significantly higher scores of subjective symptoms of fatigue than the daytime workers, and the fatigue was found to be the mental type. The subjective symptoms of fatigue scores were significantly higher in the group who had "cannot get to sleep within 30 minutes", "wake up in the middle of the night" and "wake up in the early morning". Conclusion: The study results indicated that the shift workers had the higher level of subjective symptoms of physical fatigue as well as the worse quality of sleep than the daytime workers. It is speculated that the factors attributable to the poor quality of sleep or sleep induction disorders of nurses of hospitals could be due in major part to adaptational difficulties resulting from frequent night shifts.

• Safety and Health at Work
• /
• v.12 no.2
• /
• pp.255-260
• /
• 2021

Background: A well-designed shift schedule has been reported to have a positive effect on improving health problems associated with shift work. This study aimed to identify compliance with the 17 recommendations on work schedule (WSRs) for shift nurses and related factors. Methods: The descriptive study was conducted with 182 nurses who worked in three shifts for more than 1 year at superior general and general hospitals in three regions. Data were collected with selfadministered questionnaire and 13-week work schedule tables, and analyzed with both person- and cycle-based compliance. Results: Person-based compliance was 11.77 among 17 items in total. However, no one completely complied with WSRs of "no work on weekends" and which showed the lowest cycle-based compliance (22.3%). Compliance with some WSRs was related to hospital type, proportion of nurses in school and having standards on work schedule at institutional level. Conclusion: Compliance with WSRs of shift nurses in Korea is still unsatisfactory, and one day off after night shift and work on weekend are quite common. Hospitals should keep the standards on work schedule, monitor compliance with standards, and try to introduce modified shift systems to improve the current problems.

• Safety and Health at Work
• /
• v.10 no.1
• /
• pp.109-113
• /
• 2019

Background: In both developed and developing countries, noise is regarded as the most common occupational hazard in various industries. The present study aimed to examine the effect of sound pressure level (SPL) on serum cortisol concentration in three different times during the night shift. Methods: This case-control study was conducted among 75 workers of an industrial and mining firm in 2017. The participants were assigned to one of the three groups (one control and two case groups), with an equal number of workers (25 participants) in each group. Following the ISO 9612 standard, dosimetry was adopted to evaluate equivalent SPL using a TES-1345 dosimeter. The influence of SPL on serum cortisol concentration was measured during the night shift. The serum cortisol concentration was measured using a radioimmunoassay (RIA) test in the laboratory. Repeated measure analysis of variance and linear mixed models were used with ${\alpha}=0.05$. Results: The results indicated a downward trend in the serum cortisol concentration of the three groups during the night shift. Both SPL and exposure time significantly affected cortisol concentration (p < 0.0001, p < 0.0001). Conversely, age and body mass index had no significant influence on cortisol concentration (p = 0.360, p = 0.62). Conclusion: Based on the obtained results, increasing SPL will lead to enhancement of serum cortisol concentration. Given that cortisol concentration varies while workers are exposed to different SPLs, this hormone can be used as a biomarker to study the effect of noise-induced stress.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.32 no.1
• /
• pp.91-102
• /
• 2024

This study aimed to investigate the sleep-wake patterns, social jetlag (SJL), and daytime sleepiness (DS) among air traffic controllers (ATCs) with rotating shifts. A total of 133 shift-rotating ATCs participated by completing self-report questionnaires regarding their sleep-wake patterns and DS. SJL, indicating the mid-sleep difference between workdays (W) and free days (F), was calculated for each shift. Night-shift workdays had the shortest sleep duration (SD) (5.28 hours), whereas free days following day shifts had the longest SD (6.66 hours). SJL for day and night shifts was 2.73 and 2.71 hours, respectively. The average DS score was 7.92 out of 24, with a 28.6% prevalence of DS. There was a negative correlation between SD following day shifts and SJL for the day shifts. Given these findings, it is recommended to implement effective interventions and work schedules to maintain consistent sleep patterns and minimize social jetlag to address sleep issues for shift-working ATCs.