The reason for this has to do with the hypothalamic–pituitary–adrenal axis, the brain's and body's stress response system that governs our fight-or-flight response.
O motivo ten que ver co eixe hipotalámico-hipofisario-adrenal, o sistema corporal e cerebral  de resposta ao estrés encargado de gobernar  a nosa resposta de loita ou fuxida.