According to Dr. Marcie A. Claybon, Medical Director at Chicago’s Bian, a social and wellness space, hangovers remain a bit of a medical mystery. “We know they are at least in part triggered by the toxic byproducts of alcohol metabolism,” she says. As alcohol breaks down within the body, it releases metabolites that quickly bring about the symptoms of a hangover — nausea, headaches, stomachaches, lack of energy, sweats, and even vomiting. But that’s not the only reason for the aftereffect of a but too much booze. Since alcohol acts as a diuretic, which forces the body to expel water via urine, it simultaneously imposes dehydration.