1.Risk of sleep disturbance associated with work-related activities during free time in South Korea: a cross-sectional study with mediation analysis
Ohwi KWON ; Hye-Eun LEE ; Mo-Yeol KANG
Annals of Occupational and Environmental Medicine 2026;38(1):e11-
Background:
This study aims to investigate the associations between work-related activities during free time, including frequency of working during free time and use of communication devices for work during free time, and sleep disturbance. It further explores the underlying mechanisms through mediation analysis.
Methods:
Data were analyzed from 21,473 participants of the seventh Korean Working Conditions Survey (KWCS, 2023). Multivariable logistic regression was employed to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for sleep disturbance. Three sequential models were constructed to evaluate the effects of weekly working hours and shift work on sleep disturbance risk. Mediation analysis was conducted to identify pathways linking work-related activities during free time and sleep disturbance.
Results:
Those who worked during their free time daily showed significantly higher risk of sleep disturbance (OR: 4.17; 95% CI: 2.64–6.58). Similarly, daily use of communication devices for work during free time was associated with an increased risk (OR: 1.83; 95% CI: 1.57–2.13). These associations remained robust even after adjusting for weekly working hours and shift work. Mediation analysis revealed that "worry about work while at home" was the primary mediator for device use (13.7%; 95% CI: 0.11–0.18), while "feeling too tired for housework after work" was the strongest mediator for working during free time (26.6%; 95% CI: 0.22–0.32).
Conclusions
The results indicate that engaging in work-related activities during free time elevates the risk of sleep disturbance, independent of long working hours or shift patterns. Mediation analysis revealed that the strongest effects were driven by the behavioral and psychological dimensions of work–family conflict. These findings suggest that sleep disturbance arises primarily from the erosion of work–life boundaries, fueled by persistent work-related rumination and the spillover of professional burdens into free time.
2.Association of work-time control with burnout and turnover intention: a cross-sectional analysis of a general working population in Korea
Hye-Eun LEE ; Seong-Sik CHO ; Mo-Yeol KANG
Epidemiology and Health 2026;48(1):e2026011-
OBJECTIVES:
For employees, work-time control (WTC) may protect against burnout and turnover. However, evidence from Korean workplaces is limited. This study aimed to examine whether WTC is associated with burnout and turnover intention and to test whether burnout mediates this relationship.
METHODS:
We analyzed data from 4,745 wage workers in the 2024 wave of the Korean Work, Sleep, and Health Study. WTC was assessed across 6 domains, burnout was measured using the Korean Burnout Syndrome Scale, and turnover intention was assessed using a validated 4-item scale. Logistic regression was used to estimate the associations of WTC quartile with burnout and turnover intention, and mediation analysis was used to decompose the association between WTC and turnover intention through burnout.
RESULTS:
Among 4,745 workers, the prevalence of burnout was 3.9% and turnover intention was 34.5%; both increased stepwise across lower WTC quartiles. In adjusted models, workers in the lowest WTC quartile had higher odds of burnout (odds ratio [OR], 3.95; 95% confidence interval [CI], 2.41 to 6.47) and turnover intention (OR, 2.24; 95% CI, 1.85 to 2.71) than those in the highest quartile. Mediation analysis showed that burnout explained 36.6% (95% CI, 22.3 to 51.0) of the association between WTC and turnover intention.
CONCLUSIONS
Lower WTC was linked to higher burnout and turnover intention, with burnout explaining more than one-third of this relationship.
3.Educational disparities in labor market participation among middle-aged Koreans with chronic diseases: evidence from the Korean Longitudinal Study of Elderly Employment
Seung Yeon JEON ; Dong-Wook LEE ; Jaesung CHOI ; Mo-Yeol KANG
Annals of Occupational and Environmental Medicine 2025;37(1):e19-
Background:
As South Korea experiences rapid population aging, preventing early retirement has become a critical concern. Ill health contributes to early retirement, and educational level moderates this relationship. Although well-studied in Europe, it remains less explored in Northeast Asia, where labor markets and educational attainment differ significantly. This study investigated the moderating role of education in the relationship between chronic diseases and labor force non-participation in South Korea, considering disease severity, type, and employment status.
Methods:
Using data from the Korean Longitudinal Study of Elderly Employment, this study analyzed 5,758 individuals born between 1964 and 1976. Chronic diseases were categorized by severity and type. Labor force participation and retirement from lifetime primary occupation were measured. Education was categorized as low (≤high school) or high (≥college). Logistic regression analyses were conducted, adjusting for sociodemographic and lifestyle covariates, with stratification by education level, employment status, severity, and disease characteristics.
Results:
Chronic diseases were significantly associated with labor market non-participation and early retirement, with stronger associations among individuals with lower educational levels. Educational disparities were particularly evident for severe and psychiatric disorders. Among wage workers, those with lower education were more likely to exit the labor market due to chronic diseases, whereas those with higher education generally maintained employment, except in cases of musculoskeletal diseases. Low-educated individuals with chronic diseases were also more likely to retire early from their lifetime primary occupations.
Conclusions
Education moderates the relationship between chronic diseases and labor non-participation, with greater disparities in severe or psychiatric illnesses and among wage workers. Low-educated workers are more vulnerable to early retirement due to ill health, highlighting the need for targeted policy interventions to support this group and prevent early exit from the workforce.
4.Data profile: Korean Work, Sleep, and Health Study (KWSHS)
Seong-Sik CHO ; Jeehee MIN ; Heejoo KO ; Mo-Yeol KANG
Annals of Occupational and Environmental Medicine 2025;37(1):e3-
The Korean Work, Sleep, and Health Study (KWSHS) was launched in 2022 as a longitudinal panel study to examine the interactions between work conditions, sleep health, and labour market performance among the Korean workforce. Baseline data were collected from 5,517 participants aged 19 to 70, encompassing diverse occupations. Follow-up surveys occur biannually, accommodating seasonal variations in sleep and health dynamics. To ensure stability, refreshment samples were integrated in later waves, maintaining a cohort size of 5,783 participants in wave 5. Key data include socio-demographics, employment characteristics, sleep patterns, health outcomes, and workplace performance. Early findings highlight critical associations, such as the adverse effects of occupational physical activity on productivity, the impact of emotional labour on health-related productivity loss, and the significance of sleep disruptions on mental health. The cohort’s design enables detailed analyses of longitudinal and cross-sectional trends, offering insights into how changing work environments influence health and productivity. The KWSHS could serve as a vital resource for evidence-based interventions aimed at improving occupational health and productivity in Korea's evolving labour landscape. Data access is available through the study’s principal investigator upon request.
5.Management and Collection of Occupational Data for Health (ODH) in National Public Health Statistics: Evaluation and Recommendations for Korea
Dong-Uk PARK ; Kyung Ehi ZOH ; Yun-Keun LEE ; Hoekyeong SEO ; Sangjun CHOI ; Dong-Hee KOH ; Jin-Ha YOON ; Kanwoo YOUN ; Mo-Yeol KANG ; Eun Suk CHOI ; Jungwon KIM ; Yangho KIM ; Domyung PAEK
Safety and Health at Work 2025;16(1):60-68
Background:
The aims of this study are to examine how occupation-related data and information for health (ODH) are collected and managed from census-based surveys and potential occupational illness and injuries (POIS) statistics, and to propose a national strategy for the systematic collection, analysis, and management of ODH by building on the Korean Standard Classification of Occupation (KSCO) and using a job exposure matrix (JEM).
Methods:
The status of the collection and management of ODH registered as national statistics, drawn not only from the census-based general population and workforce, but also from POIS statistics was reviewed and evaluated.
Results:
ODH from the Republic of Korea's Census of Population and Labor Force are collected and classified according to the KSCO. In contrast, national statistics on POIS are not systematically collected for KSCO coding, reflecting the lack of an KSCO and related guidelines on how to collect ODH. Key frameworks for the construction of both an KSCO and a reference JEM for public health surveillance are proposed.
Conclusions
Further research is needed to develop a national system for collecting and managing ODH, which will ultimately contribute to the use of a national KSCO and the construction of JEM for public health surveillance.
6.Occupation classification model based on DistilKoBERT: using the 5th and 6th Korean Working Condition Surveys
Tae-Yeon KIM ; Seong-Uk BAEK ; Myeong-Hun LIM ; Byungyoon YUN ; Domyung PAEK ; Kyung Ehi ZOH ; Kanwoo YOUN ; Yun Keun LEE ; Yangho KIM ; Jungwon KIM ; Eunsuk CHOI ; Mo-Yeol KANG ; YoonHo CHO ; Kyung-Eun LEE ; Juho SIM ; Juyeon OH ; Heejoo PARK ; Jian LEE ; Jong-Uk WON ; Yu-Min LEE ; Jin-Ha YOON
Annals of Occupational and Environmental Medicine 2024;36(1):e19-
Accurate occupation classification is essential in various fields, including policy development and epidemiological studies. This study aims to develop an occupation classification model based on DistilKoBERT. This study used data from the 5th and 6th Korean Working Conditions Surveys conducted in 2017 and 2020, respectively. A total of 99,665 survey participants, who were nationally representative of Korean workers, were included. We used natural language responses regarding their job responsibilities and occupational codes based on the Korean Standard Classification of Occupations (7th version, 3-digit codes). The dataset was randomly split into training and test datasets in a ratio of 7:3. The occupation classification model based on DistilKoBERT was fine-tuned using the training dataset, and the model was evaluated using the test dataset. The accuracy, precision, recall, and F1 score were calculated as evaluation metrics. The final model, which classified 28,996 survey participants in the test dataset into 142 occupational codes, exhibited an accuracy of 84.44%. For the evaluation metrics, the precision, recall, and F1 score of the model, calculated by weighting based on the sample size, were 0.83, 0.84, and 0.83, respectively. The model demonstrated high precision in the classification of service and sales workers yet exhibited low precision in the classification of managers. In addition, it displayed high precision in classifying occupations prominently represented in the training dataset. This study developed an occupation classification system based on DistilKoBERT, which demonstrated reasonable performance. Despite further efforts to enhance the classification accuracy, this automated occupation classification model holds promise for advancing epidemiological studies in the fields of occupational safety and health.
7.Exploring the impact of age and socioeconomic factors on health-related unemployment using propensity score matching: results from Korea National Health and Nutrition Examination Survey (2015–2017)
Ye-Seo LEE ; Dong-Wook LEE ; Mo-Yeol KANG
Annals of Occupational and Environmental Medicine 2024;36(1):e16-
Previous reports showed that age and socioeconomic factors mediated health-related unemployment. However, those studies had limitations controlling for confounding factors. This study examines age and socioeconomic factors contributing to health-related unemployment using propensity score matching (PSM) to control for various confounding variables. Data were obtained from the Korean National Health and Nutrition Examination Survey (KNHANES) from 2015–2017. We applied a 1:1 PSM to align health factors, and examined the association between health-related unemployment and age or socioeconomic factors through conditional logistic regression. The health-related unemployment group was compared with the employment group. Among the 9,917 participants (5,817 women, 4,100 men), 1,182 (853 women, 329 men) were in the health-related unemployment group. Total 911 pairs (629 women pairs and 282 men pairs) were retained after PSM for health factors. The results of conditional logistic regression showed that older age, low individual and household income levels, low education level, receipt of the Basic Livelihood Security Program benefits and longest-held job characteristics were linked to health-related unemployment, despite having similar health levels. Older age and low socioeconomic status can increase the risk of health-related unemployment, highlighting the presence of age discrimination and socioeconomic inequality. These findings underscore the importance of proactive management strategies aimed at addressing these disparities, which are crucial for reducing the heightened risk of health-related unemployment.
8.Association between work from home and health-related productivity loss among Korean employees
Hyo Jeong KIM ; Dong Wook LEE ; Jaesung CHOI ; Yun-Chul HONG ; Mo-Yeol KANG
Annals of Occupational and Environmental Medicine 2024;36(1):e13-
After the coronavirus disease 2019 pandemic, the widespread adoption of working from home, or teleworking, has prompted extensive research regarding its effects on work productivity and the physical and mental health of employees. In this context, our study aimed to investigate the association between working from home and health-related productivity loss (HRPL). An online survey was conducted with a sample of 1,078 workers. HRPL was estimated by the Work Productivity and Activity Impairment Questionnaire: General Health version. Workers that have been working from home in the last 6 months were categorized into the “work from home” group. Generalized linear models were used to compare the mean difference of HRPL between “work from home” and “commuters” group. Stratified analyses were conducted based on various factors including gender, age, income level, occupation, education level, previous diagnosis of chronic disease, presence of preschool children, living in studio apartment, living alone, commuting time, working hours and regular exercise. The overall HRPL was higher in the “work from home” group than in the “commuters” group with a mean difference of 4.05 (95% confidence interval [CI]: 0.09–8.01). In the stratified analyses, significant differences were observed in workers with chronic diseases (mean difference: 8.23, 95% CI: 0.38–16.09), who do not live alone (mean difference: 4.84, 95% CI: 0.35–9.33), and workers that do not exercise regularly (mean difference: 4.96, 95% CI: 0.12–9.80). Working from home is associated with an increased HRPL in the Korean working population, especially among those with chronic diseases, those who do not live alone, and those who do not exercise regularly.
9.Occupation classification model based on DistilKoBERT: using the 5th and 6th Korean Working Condition Surveys
Tae-Yeon KIM ; Seong-Uk BAEK ; Myeong-Hun LIM ; Byungyoon YUN ; Domyung PAEK ; Kyung Ehi ZOH ; Kanwoo YOUN ; Yun Keun LEE ; Yangho KIM ; Jungwon KIM ; Eunsuk CHOI ; Mo-Yeol KANG ; YoonHo CHO ; Kyung-Eun LEE ; Juho SIM ; Juyeon OH ; Heejoo PARK ; Jian LEE ; Jong-Uk WON ; Yu-Min LEE ; Jin-Ha YOON
Annals of Occupational and Environmental Medicine 2024;36(1):e19-
Accurate occupation classification is essential in various fields, including policy development and epidemiological studies. This study aims to develop an occupation classification model based on DistilKoBERT. This study used data from the 5th and 6th Korean Working Conditions Surveys conducted in 2017 and 2020, respectively. A total of 99,665 survey participants, who were nationally representative of Korean workers, were included. We used natural language responses regarding their job responsibilities and occupational codes based on the Korean Standard Classification of Occupations (7th version, 3-digit codes). The dataset was randomly split into training and test datasets in a ratio of 7:3. The occupation classification model based on DistilKoBERT was fine-tuned using the training dataset, and the model was evaluated using the test dataset. The accuracy, precision, recall, and F1 score were calculated as evaluation metrics. The final model, which classified 28,996 survey participants in the test dataset into 142 occupational codes, exhibited an accuracy of 84.44%. For the evaluation metrics, the precision, recall, and F1 score of the model, calculated by weighting based on the sample size, were 0.83, 0.84, and 0.83, respectively. The model demonstrated high precision in the classification of service and sales workers yet exhibited low precision in the classification of managers. In addition, it displayed high precision in classifying occupations prominently represented in the training dataset. This study developed an occupation classification system based on DistilKoBERT, which demonstrated reasonable performance. Despite further efforts to enhance the classification accuracy, this automated occupation classification model holds promise for advancing epidemiological studies in the fields of occupational safety and health.
10.Exploring the impact of age and socioeconomic factors on health-related unemployment using propensity score matching: results from Korea National Health and Nutrition Examination Survey (2015–2017)
Ye-Seo LEE ; Dong-Wook LEE ; Mo-Yeol KANG
Annals of Occupational and Environmental Medicine 2024;36(1):e16-
Previous reports showed that age and socioeconomic factors mediated health-related unemployment. However, those studies had limitations controlling for confounding factors. This study examines age and socioeconomic factors contributing to health-related unemployment using propensity score matching (PSM) to control for various confounding variables. Data were obtained from the Korean National Health and Nutrition Examination Survey (KNHANES) from 2015–2017. We applied a 1:1 PSM to align health factors, and examined the association between health-related unemployment and age or socioeconomic factors through conditional logistic regression. The health-related unemployment group was compared with the employment group. Among the 9,917 participants (5,817 women, 4,100 men), 1,182 (853 women, 329 men) were in the health-related unemployment group. Total 911 pairs (629 women pairs and 282 men pairs) were retained after PSM for health factors. The results of conditional logistic regression showed that older age, low individual and household income levels, low education level, receipt of the Basic Livelihood Security Program benefits and longest-held job characteristics were linked to health-related unemployment, despite having similar health levels. Older age and low socioeconomic status can increase the risk of health-related unemployment, highlighting the presence of age discrimination and socioeconomic inequality. These findings underscore the importance of proactive management strategies aimed at addressing these disparities, which are crucial for reducing the heightened risk of health-related unemployment.

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