title: Circadian type, chronic fatigue, and serum IgM in the shift workers of an industrial organization.
abstract: BACKGROUND
  Night shift workers are more vulnerable to immune-related diseases. Immunoglobulin M (IgM) is a potent activator of complement, and complement has a crucial role in defense against bacterial infections. Circadian type is known as an effective agent on vulnerability and adaptation with shift work due to non-compliance with shift stress. The objective of this study was to investigate the correlation of circadian type and chronic fatigue with the serum concentration of IgM in a group of shift workers.
  
  
  METHODS
  This cross-sectional study was performed in an industrial organization in Isfahan, Iran. The study population consisted of 221 male employees working at night shifts who were selected by random cluster sampling. The following questionnaires were used: composite morningness (Torsvall and Akerstedt), circadian type (Folkard), and chronic fatigue (Barton and colleagues). The serum concentration of IgM was measured by the nephelometric method. The data were analyzed with the Pearson coefficient correlation and the path analysis for finding the pattern of the structural equations to evaluate the direct and indirect relationships between variables, using the SPSS 15 and LISREL 8.5 statistical software.
  
  
  RESULTS
  Significant correlation was documented between morningness, flexibility, languidness, and chronic fatigue with the serum concentration of IgM (P < 0.01).
  
  
  CONCLUSIONS
  The results showed that the shift workers with morningness and languidness experienced more problems during the working hours due to more tiredness, and had decreased serum concentration of IgM. Correct management of shift work may attenuate fatigue in workers and also improve many health issues experienced by the shift workers.
authors: Department of Psychology, Naein Branch, Islamic Azad University, Naein, Iran.
authors: Shahnaz
authors: S
authors: Khaleghipour
authors: Department of Immunology, Child Growth and Development Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors: Mohsen
authors: M
authors: Masjedi
authors: Department of Pediatrics, Child Growth and Development Research Center, Isfahan University of Medical Sciences, Isfahan, Iran.
authors: Roya
authors: R
authors: Kelishadi
keywords: Circadian clocks; circadian rhythm; fatigue; immunoglobulin M; sleep disorders