Endocrine effects of sauna bath

Abstract

Sauna bath brings about numerous acute changes in hormone levels, partly akin to other stressful situations, partly specific for sauna. Norepinephrine increases in those accustomed to sauna bath. Sweating increases the production of antidiuretic hormone, and the renin-angiotensin system becomes activated. Of the anterior pituitary hormones, growth hormone (GH) and prolactin (PRL) secretion is increased. Also β-endorphin has been frequently reported to increase, whereas the responses of ACTH and cortisol are variable, probably depending on the type of sauna exposure. Sperm production decreases in particular in sauna-naïve men, but reduced fertility has not been associated with regular sauna habits. Minor sex differences exist, the hormonal responses being somewhat greater in women. Sauna-naïve women may experience mild disturbances in menstrual cycle, but no effects of fertility have been reported. The hormone responses are short-lived, normalizing soon after sauna exposure during the recovery. Adaptation to regular sauna use plays an important role in the responses, which attenuate upon frequent exposure.