Night work and inflammatory markers

Background: Various adverse health effects associated with shift work have been documented in the medical literature. These include increased risk of cardiovascular disorders, cerebrovascular disorders, and mortality. Sleep deprivation has been shown to be associated with an elevation in inflammatory makers such as interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP). It is hypothesized that the increased risk of many disorders associated with shift work may be due to inflammatory processes resulting from sleep deprivation. The purpose of this study was to investigate the relationship between night work and inflammatory markers. Materials and Methods: Fifty workers were selected according to the specified inclusion and exclusion criteria and randomly assigned to one of two groups in a cross over study. The 25 workers in group 1 were scheduled to work the following consecutive shifts: three day shifts, one day off, and three night shifts. Group 2 were scheduled to work the following consecutive shifts: three night shifts, one day off, and three day shifts. Blood samples were obtained between 7:A.M. and 8:A.M. after the periods of day work and night work and tested for inflammatory markers. Statistical Analyses: SPSS 11.5 and S-data were used to analyze data using the Student′s t-test and paired t-test. Results: There was a statistically significant increase in IL-6, CRP, white blood cells, neutrophils, lymphocytes, and platelets following night work compared with day work. TNF-α was increased but it was not statistically significant, and also the change in monocyte counts was not significant. Conclusion: This study demonstrated an increase in inflammatory markers following night work, as reported in several pervious studies on sleep deprivation. No significant changes in monocyte count can be justified by the results of a study which showed that the elevation in blood levels of inflammatory markers is due to increase in gene expression, not in monocyte counts.