BackgroundSeveral studies suggest that serum ferritin concentrations reflect systemic inflammation, and high ferritin levels can increase the risk of hypertension in adult men. Shift work is also known to increase the risk of hypertension; however, there has been no study about the relationship between serum ferritin levels and the prevalence of hypertension according to the working type.MethodsThis cross-sectional study included 4,442 male participants (3,651 daytime workers and 791 shift workers) who participated in the fifth Korean National Health and Nutrition Examination Survey. Hypertension was defined as a systolic blood pressure greater than or equal to 140 mmHg, a diastolic blood pressure greater than or equal to 90 mmHg or the current use of antihypertensive medications regardless of blood pressure values. For the statistical analyses, serum ferritin levels were reclassified into quartiles, and complex sample analyses were used to evaluate the relationship between serum ferritin levels and the prevalence of hypertension according to the working type in this study.ResultsSerum ferritin and shift work were positively associated with the prevalence of hypertension. The effect of interaction was above multiplicative. When compared to participants in the lowest serum ferritin quartile, the odds ratio for hypertension for participants in the highest serum ferritin quartile was 1.372 (1.027–1.833) in daytime workers and 2.009 (1.042–3.873) in shift workers after adjustment.ConclusionsThe prevalence of hypertension increased as ferritin levels increased in individuals, especially in shift workers.

Background: The number of workers in non-standard employment (NSE) is increasing due to industrial change and technological development. Dependent self-employment (DSE), a type of NSE, was created decades ago. Despite the problems associated with this new type of employment, few studies have been conducted on the effects by DSE on health, especially sleep quality. This study aims to determine the relationship between DSE and sleep quality. Methods: This study analyzed data of 50,250 wage workers from the fifth Korean Working Conditions Survey. Workers that did not respond or refused to answer any questions related to variables were excluded, and finally 36,709 participants were included in this study. A total of 2,287 workers (6.2%) were compared with non-DSE (34,422; 93.8%) workers, and multiple logistic regression analyses were applied. Results: DSE status had a significant association with difficulty falling asleep (odds ratio [

BackgroundMental health problems are a growing issue among customer-facing workers. This study aimed to investigate the workers' symptoms of anxiety, depression, and sleep disturbance caused by customer complaints and the suppression of one's emotions at work.MethodsThis study used the data from the fifth Korean Working Conditions Survey 2017 database. The subjects comprised 23,128 workers (men, 11,007; women, 12,121). The odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using multiple logistic regression models, to determine the effect of the exposure level of engaging with angry clients and suppressing one's emotions at work on mental health.ResultsAmong the workers engaging with angry customers, compared to the “Rarely” group as a reference point, the “Always” group showed elevated OR values (at [95% CI]) of 1.52 (1.10–2.10), 1.86 (1.05–3.27), 4.43 (3.11–6.33), 3.74 (2.51–5.55), 3.89 (2.65–5.70) for men workers; and 2.86 (1.94–4.22), 2.55 (1.73–3.75), 3.75 (2.82–4.98), 3.81 (2.84–5.09), 3.84 (2.88–5.12) for women workers, for depression, anxiety, difficulty falling asleep, waking up during sleep, and extreme fatigue after waking up, respectively. For suppressing one's emotions at work, the OR values of the “Always” group were 2.32 (1.53–3.51), 2.46 (1.73–3.50), 2.54 (1.88–3.43), 2.64 (1.92–3.64), 2.42 (1.81–3.24) for men workers; and 2.23 (1.53–3.25), 2.31 (1.61–3.33), 2.26 (1.72–2.96), 1.53 (1.19–1.97), 2.15 (1.62–2.85) for women workers, for depression, anxiety, and difficulty falling asleep, waking up during sleep, and extreme fatigue after waking up, respectively.ConclusionThe emotional labor demanded from customer-facing workers, incurred by facing customer complaints and suppressing one's emotions at work, was found to be significantly associated with the development of depression, anxiety, and sleep disturbance symptoms among the Korean working population.

BackgroundShift work is associated with a higher risk of cardiovascular diseases. Here, we sought to assess the relationship between shift work and plasma homocysteine levels. Determining the correlations between shift work and homocysteine levels may provide a better understanding of the mechanisms underlying cardiovascular diseases.MethodsThis study was performed using data from routine health examinations of steel workers in 2017. In total, 431 male workers (70 daytime workers and 361 shift workers) employed on a rolling departure schedule were recruited. Plasma homocysteine levels > 15 μmol/L were considered elevated. The χ2, analysis of variance, and multiple logistic regression analyses were used to examine the association between shift work and plasma homocysteine levels.ResultsIn comparison to daytime workers, the odds ratio (OR) of hyperhomocysteinemia in individuals with < 10 years of shift work was 1.14 (95% confidence interval [CI]: 0.64–2.03), compared to 2.01 (95% CI: 1.14–3.54) for workers with ≥ 10 years of experience. After adjusting for confounding variables, the adjusted OR for shift workers with < 10 years of experience was 0.95 (95% CI: 0.50–1.80), compared to 2.00 (95% CI: 1.07–3.74) for workers with ≥ 10 years of experience.ConclusionsThe risk of hyperhomocysteinemia was significantly higher in shift workers compared to those working normal daytime hours, particularly among long-term shift workers.