Shift work is known to cause changes in the circadian rhythm of the human body and adversely affect not only physical health but also mental health. Some studies have demonstrated the correlation between shift work and thyroid stimulating hormone (TSH), a hormone that changes according to the diurnal rhythm, but few studies have reported the different TSH levels according to the shift work type. This study aimed to investigate changes in TSH according to the shift work type.

This study included 1,318 female workers who had a medical checkup at a university hospital in Changwon from 2015 to 2019. Shift work types were classified as non-shift work, regular 2 shifts, and irregular three shifts, and a TSH ≥ 4.2 mIU/L was defined as abnormal. A general linear model (GLM) was used to compare the TSH levels and the risk of subclinical hypothyroidism in each year, and a binary logistic analysis was performed using a generalized estimation equation (GEE) to compare the risk of subclinical hypothyroidism over the 5-year period.

Of the 1,318 participants included in this study, 363, 711, and 244 were non-shift, two-shift, and irregular three-shift workers, respectively. In the GEE analysis, after adjusting for age, body mass index, smoking, and alcohol consumption, the odds ratios (ORs) were 1.81 (95% confidence interval [CI]: 1.15–2.86; p = 0.011) in 2 shifts and 2.02 (95% CI: 1.23–3.32; p = 0.006) in irregular three shifts, compared to non-shift.

Our results showed that shift work had a higher risk of subclinical hypothyroidism than non-shift work and that there was a significant difference in the risk of subclinical hypothyroidism according to the shift work type. These findings suggest that the shift work type can be considered in future thyroid function tests and evaluations.

Although coronavirus disease 2019 is causing a variety of psychological problems for workers, there are few longitudinal studies on changes in workers’ mental health by workplace intervention. This study aimed to evaluate the change in the prevalence of depression and anxiety according to the active involvement of the workplace.

This study was conducted on 1,978 workers at a workplace who underwent a health screening from January 2019 to August 2020, and classified depression and anxiety disorders using a self-report questionnaire. After the first pandemic, the company stopped health screening, took paid leave and telecommuting, and conducted interventions such as operating its own screening clinic. To see if this workplace intervention affects workers’ mental health, we conducted generalized estimating equations to compare odds ratio (OR).

In the pre-intervention group, 384 people (16.86%) had depression, and 507 people (22.26%) had anxiety disorder. Based on the OR before intervention, the OR of depression decreased to 0.76 (0.66–0.87) and the OR of anxiety disorder decreased to 0.73 (0.65–0.82).

As a result of this study, it was confirmed that workplace intervention was related to a decrease in depression and anxiety. This study provides basic data to improve workers’ mental health according to workplace intervention, and further research is needed according to workplace intervention in the future.