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., academic examinations, on the 24-h mean concentration of adrenocorticotropic hormone (ACTH), cortisol, and/or beta-endorphin. In addition, we evaluated the effect of season on the endocrine response to this stressor. We studied medical students (n = 55), screened for a variety of health and life style factors, from three consecutive medical school classes 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). Examinations produced a significant (p < .001) increase in perceived stress scores. In addition, we found a significant (p < .001) effect of examination stress on the increase in mean daytime but not nocturnal ACTH levels during autumn, but not during the spring. In contrast, the examination stress did not significantly affect day or night mean cortisol levels from baseline to examination week. We further divided the students by whether their perceived stress scores increased during examination week and fell during recovery (Group 1) or whether their perceived stress scores did not follow the expected pattern (Group 2). We found that in the Group 1 students who perceived the most stress, cortisol levels significantly increased (p < .001) from baseline to examination. Therefore, the nature of the stressor and the state of the responder were of equal importance in the observed cortisol response during examinations 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 concentrations, however, was not observed. In summary, we have demonstrated that stress associated with the taking of examinations produces a dissociation among mean 24-h levels of ACTH, cortisol, and beta-endorphin. In addition, daytime cortisol levels increased during examinations only in the group of students whose perceived stress scores increased. Further, a seasonal influence on ACTH secretion was suggested by these results with higher levels observed in the spring than in the fall.