Plasma testosterone levels were determined in 18 young men in Officer Candidate School. Plasma testosterone levels were significantly lower during the early, stressful part of the course as contrasted with levels during the senior phase. This finding represents the first evidence in humans supporting the hypothesis that psychological stress suppresses levels of circulating plasma testosterone.
Kreuz MLE, Rose RM, Jennings CJR. Suppression of Plasma Testosterone Levels and Psychological StressA Longitudinal Study of Young Men in Officer Candidate School. Arch Gen Psychiatry. 1972;26(5):479-482. doi:10.1001/archpsyc.1972.01750230089017