Night shift work exposure profile and obesity: Baseline results from a Chinese night shift worker cohort.

Mingshen Sun ,Gary Tse,Liuzhuo Zhang,Bo Zhang,Roel Vermeulen,Zhimin Li,Lap Ah Tse,Wenting Feng,Feng Wang,Jelle Vlaanderen,Mengjie Li,Samuel Yeung Shan Wong ,Martin Cs Wong ,Wu Z ,Yao He ,Joan P.c Fok ,Greg J Evans ,Jin‐Ling Tang ,Shao-Hua Xie

doi:10.1371/journal.pone.0196989

Abstract

AimsThis study aimed to evaluate the associations between types of night shift work and different indices of obesity using the baseline information from a prospective cohort study of night shift workers in China.MethodsA total of 3,871 workers from five companies were recruited from the baseline survey. A structured self-administered questionnaire was employed to collect the participants’ demographic information, lifetime working history, and lifestyle habits. Participants were grouped into rotating, permanent and irregular night shift work groups. Anthropometric parameters were assessed by healthcare professionals. Multiple logistic regression models were used to evaluate the associations between night shift work and different indices of obesity.ResultsNight shift workers had increased risk of overweight and obesity, and odds ratios (ORs) were 1.17 (95% CI, 0.97–1.41) and 1.27 (95% CI, 0.74–2.18), respectively. Abdominal obesity had a significant but marginal association with night shift work (OR = 1.20, 95% CI, 1.01–1.43). A positive gradient between the number of years of night shift work and overweight or abdominal obesity was observed. Permanent night shift work showed the highest odds of being overweight (OR = 3.94, 95% CI, 1.40–11.03) and having increased abdominal obesity (OR = 3.34, 95% CI, 1.19–9.37). Irregular night shift work was also significantly associated with overweight (OR = 1.56, 95% CI, 1.13–2.14), but its association with abdominal obesity was borderline (OR = 1.26, 95% CI, 0.94–1.69). By contrast, the association between rotating night shift work and these parameters was not significant.ConclusionPermanent and irregular night shift work were more likely to be associated with overweight or abdominal obesity than rotating night shift work. These associations need to be verified in prospective cohort studies.

Highlights

Prolonged exposure to shift work, to irregular night shifts, has been associated with higher risks of obesity, metabolic syndrome, cardiovascular diseases, and breast cancer [1, 2]
Night shift workers had increased risk of overweight and obesity, and odds ratios (ORs) were 1.17 and 1.27, respectively
Abdominal obesity had a significant but marginal association with night shift work (OR = 1.20, 95% 95% confidence interval (CI), 1.01–1.43)

Summary

Introduction

Prolonged exposure to shift work, to irregular night shifts, has been associated with higher risks of obesity, metabolic syndrome, cardiovascular diseases, and breast cancer [1, 2]. Previous epidemiological studies have provided evidence that shift work may be a contributing factor in overweight or obesity, but a majority of these studies were conducted in Western populations [7,8,9], and few studies have examined these associations in Chinese populations. Abdominal obesity, which is an important risk factor of cardiovascular diseases in Western and Asian populations, has been reported to be associated with night shift work [15,16,17]. These findings have been controversial [18, 19].

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Results

Conclusion