Background: Shift work has been associated with adverse health effects by disturbing circadian rhythms. However,its potential long-term health effects and the persistent effects after leaving shifts have not been well established.
Methods and results: We studied 26,463 workers from Tongji-Dongfeng Cohort in China. All the participants are retired employees of Dongfeng Motor Company. Information on demographics, occupational history and medical history were gathered through questionnaires. After adjusting potential confounders in the logistic regression models, shift work was associated with poor sleeping quality, diabetes and hypertension independently. We observed significant effects of shift work on poor sleeping quality, diabetes and hypertension; the ORs (95%CI) are 1.18 (1.09-1.27), 1.10 (1.03-1.17) and 1.05 (1.01-1.09) respectively. In the further analysis, we found elevated ORs (95%CI) for participants with poor sleeping quality, the ORs (95%CI) are 1.34 (1.08-1.60), 1.13 (1.05-1.21), 1.05 (1.03-1.07) and 1.05 (1.01-1.09) for 1-4, 5-9, 10-19, ≥20 years of shift work respectively. However, with the extension of leaving shift work duration, the effects of shift work on sleep quality gradually reduced.
Conclusions: Shift work may be an independent risk factor for sleeping quality, diabetes and hypertension even in retired workers. Applicable intervention strategies are needed for prevention of sleep loss, diabetes, and hypertension for shift workers.