When epilepsy patients die unexpectedly from one of their seizures, they are said to have succumbed to sudden unexpected death in epilepsy (SUDEP). Such seizures cause their victims to become apneic (to stop breathing), to slow down their heart rates, and to progress to cardiac arrest and death. At autopsy (when available), the majority of SUDEP victims demonstrate pulmonary edema.

One would think SUDEP is a rare occurrence, but estimates suggest it takes the lives of 7-17% of people with epilepsy!

While the cause of SUDEP is not known, humans are predisposed to preserve their brains and hearts when breathing stops by triggering the same set of reflexes that allows air-breathing marine mammals to spend hours underwater. This set of reflexes, known as the mammalian dive (or diving) response (MDR), slows down the heart rate and sequesters most of the blood volume inside the lungs, heart, and brain. Could the physiological consequences of the MDR explain SUDEP?