Relationship between effort–reward imbalance and hair cortisol concentration in female kindergarten teachers

Abstract Objective The present study aims to investigate the relationship between effort–reward imbalance and hair cortisol concentration among teachers to examine whether hair cortisol can be a biomarker of chronic work stress. Methods Hair samples were collected from 39 female teachers from three kindergartens. Cortisol was extracted from the hair samples with methanol, and cortisol concentrations were measured with high performance liquid chromatography–tandem mass spectrometry. Work stress was measured using the effort–reward imbalance scale. Results The ratio of effort to reward showed significantly positive association with hair cortisol concentration. Conclusion The cortisol concentration in the system increases with the effort–reward imbalance. Measurement of hair cortisol can become a useful biomarker of chronic work stress.