Cumulative cortisol exposure increases during the academic term: Links to performance-related and social-evaluative stressors.

OBJECTIVE

To examine whether cumulative cortisol production changes during a period of increased demands when cortisol and stress are assessed concurrently. The study also compared stress perceptions vs. cumulative stressful events on their respective association with cortisol output. Finally, it explored whether certain types of stressful events, those involving school/job performance or social-evaluative threat, were linked to cortisol levels across multiple weeks.

METHOD

The current study assessed cumulative cortisol production via hair sample in 56 undergraduates (88 % female) during both lower stress (summer break) and higher stress (academic term) periods. During the latter, both negative events (checklist) and stress perceptions were assessed weekly, and these reports were aggregated across the 10-weeks to minimize retrospective bias.

RESULTS

Cortisol levels in hair samples were significantly higher (d = 0.84) during the academic term (M = 14.24 pg/mg, SD = 11.36) compared to summer break (M = 8.00 pg/mg, SD = 4.14), suggesting greater cumulative exposure to cortisol. Although perceived stress was not associated with cortisol levels (r(53) = .10, p = 0.46), exposure to more stressful events (r(53) = .27, p = 0.047), particularly events involving academic demands (r(53) = .37, p = 0.006), or negative evaluation/social rejection (r(53) = .27, p = 0.045), was positively associated with cumulative cortisol exposure.

CONCLUSIONS

This study demonstrates that cortisol levels in hair may be linked to cumulative exposure to stressors when measured concurrently (3 months), and that stressful events, rather than perceptions, are reflected in HPA axis activity. Real-world stressors involving performance demands and social-evaluative threat accumulate to enhance cortisol production, consistent with their acute HPA effects in the lab. Hair samples may provide a window into the past by allowing researchers to feasibly assess cortisol production before, during, and after the onset of a chronic stressor.