The influence of academic stress and season on 24-hour concentrations of growth hormone and prolactin

Stress has been considered a physiological regulator of GH and PRL secretion in humans. The stressors used in studies have often been extreme. The influence of common-place stressors on the endocrine system has not been clarified. Therefore, to better define the role of commonplace stressors on GH and PRL secretion, we evaluated the effect of examination stress on GH and PRL secretion in 37 male medical students. We performed hourly sampling for 24 h for GH and PRL 4 weeks before, during exam week, and 2 weeks after major examinations in the fall and spring of their first year. Stress, as evaluated by the Perceived Stress Scale (PSS), increased as expected during examination weeks, but there was no correlation between the PSS scores and mean day or night GH and PRL secretion. Twenty-four-hour GH and PRL secretion was not significantly altered during examinations in either fall or spring. A significant seasonal influence, however, was noted on GH secretion, with both daytime and nocturnal GH secretion being consistently higher in the Fall than in the Spring. We conclude that examination stress does not significantly influence mean daytime or nocturnal GH and PRL concentrations. We suggest that serum GH and PRL levels may not be significantly altered in man by commonplace stressors. Also, seasonal effects may be operative in the control of human GH secretion.