In meicine, a coma (from the Greek κῶμα koma, meaning deep sleep) is a profound state of unconsciousness. A comatose patient cannot be awakened, fails to respond normally to pain or light, does not have sleep-wake cycles, and does not take voluntary actions. Coma may result from a variety of conditions, including intoxication, metabolic abnormalities, central nervous system diseases, acute neurologic injuries such as stroke, and hypoxia. It may also be deliberately induced by pharmaceutical agents in order to preserve higher brain function following another form of brain trauma, or to save the patient from extreme pain during healing of injuries or diseases. A coma may also result from immense head trauma caused by something like a car accident or a series of very severe concussions. The underlying cause of the coma is bilateral damage to the Reticular formation of the midbrain, which is important in regulating sleep.