Nighttime shift work and related stress responses: study on security guards

Work-related stress can induce a break in homeostasis placing demands on the body that are met by the activation of two different systems, the hypothalamic-pituitary-adrenal axis, and the sympathetic nervous system. Night shift work alters the exposure to the natural light–dark schedule and disrupts circadian (that is daily) rhythms. The greatest effect of night shift work is the circadian rhythms disruption. It is unknown to what extent these disruptions may provoke the pathogenesis of many diseases, including cancer. This study aims to discover the relationship among three different job activities of security guards and stress related responses by salivary cortisol and blood pressure evaluations. Methods. Ninety security guards, divided in: nighttime workers, nighttime and daily-shift workers were recruited for this study. Each security guard provided two saliva samples before and after three scheduled steps : (i) 10:00 p.m., (ii) 06:30 a.m. and (iii) at 14:00 p.m. Results. The results of the study showed a significant alteration in cortisol levels. In particular, in nighttime shift cortisol levels significantly increase before and after the work shift. Moreover, it was found a physiological prevalence of the vagal tone on the cardiocirculatory activity during the night shift work . Conclusions. This study indicates that cortisol and- blood pressure are sensitive markers of biological responses to severe work stress. Therefore, shift change consequences occur at the end of the night shift when there is a significant cortisol level increase and a significant cardiovascular parameters variation.