Article Text

Original research
Relationships among shift work, hair cortisol concentration and sleep disorders: a cross-sectional study in China
  1. Yu Zhang1,
  2. Jiayang Shen1,
  3. Ziqi Zhou1,
  4. Lingli Sang1,
  5. Xun Zhuang1,
  6. Minjie Chu1,
  7. Tian Tian1,
  8. Jing Xiao2,
  9. Yulong Lian1
  1. 1Department of Epidemiology and Medical Statistics, School of Public Health, Nantong University, Nantong, Jiangsu, China
  2. 2Department of Occupational Environmental Toxicology, School of Public Health, Nantong University, Nantong, Jiangsu, China
  1. Correspondence to Dr Yulong Lian; lianyulong444{at}


Objective The present study was designed to demonstrate the relationships among shift work, hair cortisol concentration (HCC) and sleep disorders.

Design A cross-sectional study.

Setting Three petroleum administrations in Karamay city of Xinjiang, China.

Participants 435 individuals including 164 males and 271 females participated in the research.

Outcome measures Information on shift work was collected by a self-administered questionnaire. HCC was determined using an automatic radioimmunoassay instrument. Sleep quality was measured on the Pittsburgh Sleep Quality Index scale.

Results Shiftwork was associated with an increased prevalence of sleep disorders compared with the fixed day shift (two shifts: OR 3.11, 95% CI 1.57 to 6.19; three shifts: OR 2.87, 95% CI 1.38 to 5.98; four shifts: OR 2.22, 95% CI 1.17 to 4.18; others: OR 3.88, 95% CI= 1.36 to 11.08). Workers with different shift patterns had higher HCC levels than day workers ((fixed day shift: geometric mean±geometric SD=2.33±1.65; two shifts: 3.76±1.47; three shifts: 3.15±1.64; four shifts: 3.81±1.55; others: 3.60±1.33) ng/g hair, η2=0.174) and high HCC was associated with the higher prevalence of sleep disorders (OR 4.46, 95% CI 2.70 to 7.35). The mediating effect of HCC on the relationship between shift work and sleep disorders was 0.25 (95% CI 0.09 to 0.41).

Conclusion We found that, when compared with the fixed day shift, shiftwork was associated with both the higher HCC, and also with an increased risk of sleep disorders. High HCC was associated with the occurrence of sleep disorders. In addition, HCC had mediating effect in shift work and sleep disorders. Thus, HCC can be considered as an early marker of shiftwork circadian disruption to early detection and management of sleep disorders.

  • sleep medicine
  • occupational & industrial medicine
  • epidemiology

This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See:

Statistics from

Supplementary materials

  • Supplementary Data

    This web only file has been produced by the BMJ Publishing Group from an electronic file supplied by the author(s) and has not been edited for content.


  • Contributors YL, YZ, JS, ZZ, LS, XZ, MC, TT and JX participated in study conception and design. All authors participated in acquiring data. YL and YZ participated in drafting of manuscript. YZ, JS, ZZ and LS contributed to analysis and interpretation of data. All authors participated in the critical revision and have approved the article.

  • Funding This work was supported by the Natural Science Foundation of Jiangsu Province, China (Grant Number: BK20171256); Qinglan Project of Jiangsu Province of China (Jiangsu Provincial Education Department,

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval The study was approved by the Ethics Committees of Nantong University (2013-L073).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available on reasonable request. All data relevant to the study are included in the article or uploaded as online supplementa information. Extra data are available by emailing YL.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.