You don't necessarily need a fancy device to stimulate the vagus nerve. Patients with supraventricular tachycardias are taught to do vagal maneuvers, the simple

You don't necessarily need a fancy device to stimulate the vagus nerve. Patients with supraventricular tachycardias are taught to do vagal maneuvers, the simplest of which is gagging: http://www.webmd.com/heart-disease/atrial-fibrillation/tc/vagal-maneuvers-for-a-fast-heart-rate-topic-overview http://www.webmd.com/heart-disease/atrial-fibrillation/tc/va... In general, imbalance within the autonomic nervous system (of which the vagus nerve controls half—the parasympathetic portion) has been shown to be related to everything from heart disease to irritable bowel syndrome to having an irritable personality: http://en.wikipedia.org/wiki/Autonomic_nervous_system http://en.wikipedia.org/wiki/Autonomic_nervous_system