Abstract
BackgroundCumulative epidemiological evidence suggests that shift work exerts harmful effects on human health. However, the physiological mechanisms are not well understood. This study aimed to examine the impact of shift work on the dysregulation of the hypothalamic-pituitary-adrenal axis, i.e. diurnal cortisol rhythm.MethodsSeventy physicians with a mean age 30 years participated in this one-year longitudinal study. Working schedules, either shift work or regular schedules with day shift, were assessed at baseline. Salivary cortisol samples were collected on two consecutive regular working days, four times a day (including waking, + 4 h, + 8 h, and + 16 h), at both baseline and the one-year follow-up. The diurnal cortisol decline (slope) and total cortisol concentration (area under the curve, AUC) were calculated.ResultsAfter adjusting for cortisol secretion at baseline and numerous covariates, shift work at baseline significantly predicted a steeper slope (p < 0.01) and a larger AUC (p < 0.05) of diurnal cortisol rhythm at follow-up in this sample of physicians. In particular, waking cortisol at follow-up was significantly higher among those engaged in shift work than day shift (p < 0.01).ConclusionsOur findings support the notion that shift work changes the diurnal cortisol pattern, and is predictive of increased cortisol secretion consequently in junior physicians.
Highlights
Cumulative epidemiological evidence suggests that shift work exerts harmful effects on human health
In 2007 the World Health Organization International Agency for Research on Cancer announced the probable association between shift work and cancer risk [4], breast cancer in women [5] and prostate cancer in men [6]; in addition, it has been
Seventy-six percent were living with partners, and 83% had no children
Summary
Cumulative epidemiological evidence suggests that shift work exerts harmful effects on human health. Several chronic health conditions have been identified to be related to shift work [3]. In 2007 the World Health Organization International Agency for Research on Cancer announced the probable association between shift work and cancer risk [4], breast cancer in women [5] and prostate cancer in men [6]; in addition, it has been. Some physiological mechanisms have been proposed to explain links between shift work and adverse health outcomes. Shift work-caused disruption of the circadian time organization is one core explanation, which exerts far-reaching effects at the molecular and cellular levels. Exposure to shift work during one’s occupational career, through the close physiological interaction of circadian clock-related and cell-cycle factors, may result in a variety of processes that initiate epigenetic modifications, with malignant potential. Melatonin which is produced in the pineal gland and circulated during darkness has received significant attention
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