Night shift work and the risk of metabolic syndrome: Findings from an 8-year hospital cohort.

Wan-Ju Cheng,Yu-Fang Cheng,Kai-Chieh Hu,Kati Karhula,Chiu-Shong Liu,Mikko Härmä,Girish C Melkani

doi:10.1371/journal.pone.0261349

Abstract

ObjectivesStudies concerning the risk of metabolic syndrome associated with night work have shown inconsistent findings, due to imprecise working time data and cross-sectional design. We used register-based daily working time data to examine the risk of incident metabolic syndrome associated with night shift work.MethodsWorking time data collected between 2010 and 2018 of 5775 Taiwanese hospital workers were used to identify night shift workers and to calculate the number of night shifts. Metabolic syndrome was identified by annual occupational health examination results, which were linked to the working time data. Logistic regression models and generalized estimating equations were used to examine the association between night shift work and metabolic syndrome and the 5 components of metabolic syndrome.ResultsNight shift work is associated with a higher risk of developing metabolic syndrome (adjusted OR = 1.36, 95% CI = 1.04 to 1.78) and high waist circumference (adjusted OR = 1.27, 95% CI = 1.07 to 1.78) compared to day work. Among night shift workers, increased number of night shifts was associated with high blood pressure (adjusted OR = 1.15, 95% CI = 1.01 to 1.31).ConclusionsNight shift work is associated with metabolic risk factors. Long-term effects of circadian rhythm disruption on metabolic disturbances needs to be further studied.

Highlights

Metabolic syndrome, characterized by glucose intolerance, hypertension, dyslipidemia, and central obesity, increases the risks of cardiovascular disease, stroke, diabetes mellitus, and cognitive decline [1,2,3,4]
Night shift work is associated with a higher risk of developing metabolic syndrome and high waist circumference compared to day work
Among night shift workers, increased number of night shifts was associated with high blood pressure

Summary

Introduction

Metabolic syndrome, characterized by glucose intolerance, hypertension, dyslipidemia, and central obesity, increases the risks of cardiovascular disease, stroke, diabetes mellitus, and cognitive decline [1,2,3,4]. The prevalence of metabolic syndrome is between 5% and 20% among employees [5]. Scientific evidence for the association between shift work and metabolic syndrome is inconsistent [5, 9]. Wang et al reported the increased risk of metabolic syndrome among workers who had been exposed to night shift work [9]. A meta-analysis of longitudinal studies found that shift work was associated with overweight and elevated blood glucose, whereas the association with lipid metabolism and blood pressure was not supported [10]

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Discussion

Conclusion