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Sleep Disorders
Volume 2012, Article ID 789274, 5 pages
Research Article

Morning Cortisol Levels and Perceived Stress in Irregular Shift Workers Compared with Regular Daytime Workers

1Centre of Excellence of Health and Work Ability, Finnish Institute of Occupational Health, 00250 Helsinki, Finland
2Institute of Dentistry, University of Helsinki, 00014 Helsinki, Finland
3Department of Cardiology, Helsinki University Central Hospital, 00029 Helsinki, Finland
4Centre of Excellence of Human Factors at Work, Finnish Institute of Occupational Health, 00250 Helsinki, Finland
5Helsinki Sleep Clinic, Vitalmed Research Centre, 00420 Helsinki, Finland
6Department of Public Health, University of Helsinki, 00014 Helsinki Helsinki, Finland
7Finnish Broadcasting Company and Department of Public Health, University of Helsinki, 00014 Helsinki, Finland

Received 8 December 2011; Revised 15 March 2012; Accepted 29 March 2012

Academic Editor: M. J. Thorpy

Copyright © 2012 Harri Lindholm et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The 24/7 work environment and irregular shifts may markedly enhance the psychological pressure of media work. Changes in the hypothalamic-pituitary-adrenal axis reflect adaptation to stress. We analysed the correlation between subjective stress, sleep, salivary cortisol, and melatonin hormones among Finnish media workers with regular daytime work (RDW) and with irregular shift work (ISW) while controlling confounders. From 874 employees with regular daytime work or with irregular shift work, 70 employees from both groups were randomly selected. The final number of employees with a complete salivary cortisol profile was 66 in the RDW group and 65 in the ISW group. Five saliva samples were gathered from each subject before and during a working day. The salivary cortisol level of the sample taken 60 minutes after awakening (T1) was compared to the salivary cortisol level taken immediately after awakening (T0, T1/T0 ratio). The ratio was higher in the ISW group than in RDW group. Irregular shift work ( ), severe stress ( ), and less sleep ( ) were independently associated with an augmented cortisol response after awakening. A stressful work environment and irregular shift work enhance cortisol excretion after waking. In the long run, this may become detrimental to health.