Whether regular working hours can minimize the blood biochemical effects of shift working: a cross-sectional study in Iran

Background: Irregular Working hours, including night work and shift work, have been found to be associated with alteration in various levels of biochemical factors. an‎d some studies have showed association between shift work and blood biochemical disturbances in blood. In this epidemiological study we investigated, whether regular schedule of working hours can minimize the associated biochemical effects. Methods:Atotal of 442 air traffic controllers between the ages of 21 and 59 years in this study filled out questionnaire, and triglyceride, total cholesterol, and HDL-C concentration and FBS were measured after 12- hours fasting. The correlation between shift work and the biochemical variables was measured. The SPSS software version 11.5 and STATAversion 8 were used for statistical analysis, the X2 and fisher's exact test used for comparing the qualitative variables and the parametric tests for quantitative variables with normal distribution. Odd's ratio (OR), and 95% confidence interval (95% CI) were used for estimating the effect of shift work on lipid profile and high blood glucose levels. Logistic regression modeling was used for multivariable analysis and adjusting the effect of different variables. Results: sample size of this cross-sectional study was consisted of 305(69%) shift workers and 137(31%) day workers. The mean age of the shift workers was 40 ± 10 years old and the day workers 40 ± 9.The mean of variables in the present study for total cholesterol, LDL-C, HDL-C, triglyceride and fasting blood glucose in the shift workers were respectively: 195±37mg/dl, 116.8±34.8mg/dl, 48.2±15.1mg/dl, 154±80mg/dl, 92±20mg/dl and in the day workers were respectively: 200±40mg/dl, 125.3±38.6mg/dl, 48.8±23.3mg/dl,151± 77mg/dl, 90± 14mg/dl. Adjusted Odd's ratio for the effect of shift working on the biochemical blood factors did not change the results. . Conclusion: This study showed that air traffic control workers with various shift did not have any disturbances in their biochemical blood factors, and this finding persisted after adjustment was made for age. These results could be due to regular shift schedule as well as periodic evaluation for biochemical blood factors in this group. But this study did not rule out physiological and behavioral effects of working shift on the shift workers. It was concluded that shift workers should be on regular working schedule and examined periodically for biochemical blood factors, physiological flunctuation (gastrointestinal, endocrinal, cardiovascular….) and behavioral effects induced by variation in shift working.