Patterns of salivary cortisol levels can manifest work stress in emergency care providers

Abstract

To develop objective assessments of work fatigue, we investigated the patterns of changes in salivary cortisol levels in emergency care providers working extended work shifts. Fourteen subjects, comprising seven physicians and seven physician assistants, provided unstimulated saliva samples at regular intervals over the course of a 24-h work shift and over their subsequent free day. There was a significant time effect, with early morning cortisol levels being significantly attenuated following the work shift. Native diurnal variations varied by gender, with the female subjects manifesting greater cortisol levels. Physicians also had higher cortisol profiles even though their wake-rest cycles were similar to those of the physician assistants. Our results suggest that temporal changes, as well as diurnal similarities, in the salivary cortisol patterns can reflect work-related stress and recovery. In particular, early morning cortisol levels may manifest individual reactivity to work stressors as well as sleep deprivation.

Conflict of interest statement

The authors declare that they have no conflict of interest.

Figures

Fig. 1

Summary of repeated saliva sampling time points. A1 Morning of work day, A2 before evening meal of work day, A3 around midnight of work day, A4 morning following work day (morning of free day), A5 before evening meal of day off, A6 bedtime of day off, A7 morning following day off

Fig. 2

Scatter plot matrix from 289 samples with 95% equal probability ellipse and correlation coefficient between the variables. A1–A7 Sampling time points (see Fig. 1) over the 48-h study cycle, r correlation coefficient

Fig. 3

Mean diurnal variations in salivary cortisol on extended work days and day offs. *p < 0.01. NS Not significant

Fig. 4

Mean diurnal variations of salivary cortisol on work days (A1–A4) and on days off (A4–A7) in physicians (P; n = 7) and physician assistants (PA; n = 7). *p < 0.01. NS not significant

Fig. 5

Similarities in diurnal variations between mean diurnal curve and individual diurnal curves on the work day (n = 39) versus day off (n = 39). Horizontal black lines Mean value in each group, S similarity of diurnal variation, W work day, O day off, NS not significant. #Difference exceeded 3 standard deviations