Background: Although insomnia and constipation are highly prevalent worldwide, studies examining a possible association between them are lacking. We examined the relationship between insomnia and constipation in shift workers who have a high prevalence of insomnia and other diseases. Methods: This study had a multicenter cross-sectional design and conducted using health examination data including self-reported questionnaires. In total, 12,879 and 4,650 shift workers were enrolled in Severance Hospital and Wonju Severance Hospital, respectively, during 2015-2017. Multivariate logistic regression models and subgroup analysis were performed in each center with the same protocol, using a common data model. Results: The mean age of the total population was 44.35 (standard deviation = 8.75); the proportion of males was 56.9%. Female sex, being underweight and non-smoker were strongly associated with an increased risk of constipation symptom (p < 0.001). Pooled odds ratios (ORs) were calculated using ORs of both centers with weights; there was a significant dose–response relationship (sub-threshold 1.76 [95% confidence interval [CI] 1.62–1.91]; moderate 2.28 [95% CI 2.01–2.60]; severe 4.15 [95% CI 3.18–5.41] in the final model, p for trend < 0.001). Subgroup analysis performed by stratifying sex and pooled ORs showed a similar trend to that of the entire group. Conclusion We observed a strong correlation between insomnia and constipation in this population. Our findings may help in formulating guidelines and policies to improve quality of life in shift workers through the management of sleep quality and proper bowel function. This study is the first to report this relationship among people working in shifts.

Background: Replacement drivers represent a significant portion of platform labor in the Republic of Korea, often facing night shifts and the demands of emotional labor. Research on replacement drivers is limited due to their widespread nature. This study examined the levels of presenteeism and absenteeism among replacement drivers in comparison to those of paid male workers in the Republic of Korea. Methods: This study collected data for replacement drivers and used data from the 6th Korean Working Conditions Survey for paid male workers over the age of 20 years. Propensity score matching was performed to balance the differences between paid workers and replacement drivers. Multivariable logistic regression was used to estimate the adjusted odds ratio (OR) and 95% confidence intervals for presenteeism and absenteeism by replacement drivers. Stratified analysis was conducted for age groups, educational levels, income levels, and working hours. The analysis was adjusted for variables including age, education, income, working hours, working days per week, and working duration. Results: Among the 1,417 participants, the prevalence of presenteeism and absenteeism among replacement drivers was 53.6% (n = 210) and 51.3% (n = 201), respectively. The association of presenteeism and absenteeism (adjusted OR [95% CI] = 8.42 [6.36−11.16] and 20.80 [95% CI = 14.60−29.62], respectively) with replacement drivers being significant, with a prominent association among the young age group, high educational, and medium income levels. Conclusion The results demonstrated that replacement drivers were more significantly associated with presenteeism and absenteeism than paid workers. Further studies are necessary to establish a strategy to decrease the risk factors among replacement drivers.

Background: This study assessed the relationship between non-participation in health checkups and all-cause mortality and morbidity, considering socioeconomic status. Methods: Healthy, middle-aged (35–54 years) working individuals who maintained either self-employed or employee status from 2006–2010 were recruited in this retrospective cohort study from the National Health Insurance Service in Korea. Health check-up participation was calculated as the sum of the number of health check-ups in 2007–2008 and 2009–2010.Adjusted hazard ratio (HR) and 95% confidence interval (CI) of all-cause mortality were estimated for each gender using multivariable Cox proportional hazard models, adjusting for age, income, residential area, and employment status. Interaction of non-participation in health check-ups and employment status on the risk of all-cause mortality was further analyzed. Results: Among 4,267,243 individuals with a median 12-year follow-up (median age, 44;men, 74.43%), 89,030 (2.09%) died. The proportion (number) of deaths of individuals with no, one-time, and two-time participation in health check-ups was 3.53% (n = 47,496), 1.66% (n = 13,835), and 1.33% (n = 27,699), respectively. The association between health checkup participation and all-cause mortality showed a reverse J-shaped curve with the highest adjusted HR (95% CI) of 1.575 (1.541–1.611) and 1.718 (1.628–1.813) for men and women who did not attend any health check-ups, respectively. According to the interaction analysis, both genders showed significant additive and multiplicative interaction, with more pronounced additive interaction among women who did not attend health check-ups (relative excess risk due to interaction, 1.014 [0.871−1.158]). Conclusion Our study highlights the significant reverse J-shaped association between health check-up participation and all-cause mortality. A pronounced association was found among self-employed individuals, regardless of gender.