INFLUENCE OF ACADEMIC STRESS AND SEASON ON 24-HOUR MEAN CONCENTRATIONS OF ACTH, CORTISOL, AND BETA-ENDORPHIN

We investigated the influence of a common stressful event, i.e., acade mic examinations, on the 24-h mean concentration of adrenocorticotropi c hormone (ACTH), cortisol, and/or beta-endorphin. In addition, we eva luated the effect of season on the endocrine response to this stressor . We studied medical students (n = 55), screened for a variety of heal th and life style factors, from three consecutive medical school class es 1 month before, during, and 2 weeks following examinations. Hourly blood samples were obtained from an indwelling catheter and two serum pools were made (0800-2200h = day and 2300-0700h = night). Examination s produced a significant (p < .001) increase in perceived stress score s. In addition, we found a significant (p < .001) effect of examinatio n stress on the increase in mean daytime but not nocturnal ACTH levels during autumn, but not during the spring. In contrast, the examinatio n stress did not significantly effect day or night mean cortisol level s from baseline to examination week. We further divided the students b y whether their perceived stress scores increased during examination w eek and fell during recovery (Group 1) or whether their perceived stre ss scores did not follow the expected pattern (Group 2). We found that in the Group 1 students who perceived the most stress, cortisol level s significantly increased (p < .001) from baseline to examination. The refore, the nature of the stressor and the state of the responder were of equal importance in the observed cortisol response during examinat ions among these students. Further, academic stress had no significant effect on beta-endorphin levels. Finally, we found that the mean day and night ACTH levels were higher (p < .001) in the spring than in the fall; a seasonal influence on cortisol and beta-endorphin concentrati ons, however, was not observed. In summary, we have demonstrated that stress associated with the taking of examinations produces a dissociat ion among mean 24-h levels of ACTH, cortisol, and beta-endorphin. In a ddition, daytime cortisol levels increased during examinations only in the group of students whose perceived stress scores increased. Furthe r, a seasonal influence on ACTH secretion was suggested by these resul ts with higher levels observed in the spring than in the fall.