Laughter reduces the secretion of both stress hormones (so-called): adrenalin and cortisol. A good sustained belly laugh results in a rise in endorphin production and a decrease in adrenaline and cortisol. Laughter is the best medicine. (O’Brien, Mary, MD. Successful Aging. p 30-31, 152-153. CA: Biomed General. 2007.)

Laughter may help to dissipate hormones (e.g., adrenalin) that have increased due to actual or anticipation of confrontations or threatening situations. (Greenfield, Susan A., Con. Ed. Brain Power. p 159-161. MA: The Ivy Press Limited, 1999.)