Hormones mediate the stress response, explains Jörg Bojunga, who heads the Department of Endocrinology, Diabetology and Nutritional Medicine at the University Hospital in Frankfurt. The main stress hormones are cortisol and adrenaline. They flood the body. What nature came up with is actually ingenious. “The problem is that our evolutionary stress response doesn’t match the situations in which we are stressed today. You are supposed to react when you see a lion in the steppe. Then you should run or fight,” says Bojunga. “Neither of them fits when you’re sitting at your desk.” In the case of constant stress, the endocrine system can go haywire, which can lead to illnesses.