A condition in which a person has lost cognitive neurological function and awareness but retains noncognitive (automatic) functions and a sleep-wake cycle. A persistent vegetative state sometimes follows a COMA. The prognosis depends on the nature and cause of the neurological damage. Some people regain a certain amount of awareness after a vegetative state. Others remain in this condition for many years without recovering. Pneumonia is the most common cause of death for people who are in a vegetative state.