What characterizes a state of coma?

A state of coma is characterized by a level of consciousness where no external stimulus can elicit a response. This means that the individual is unresponsive to their environment and cannot be awakened, even with vigorous stimulation. In this state, the patient is neither aware of their surroundings nor can they interact with others, placing them in a profound state of altered consciousness.

This condition is distinct from states of arousal with awareness, which involve a level of conscious experience and responsiveness to stimuli. A coma does not allow for any conscious processing or reaction. Additionally, a temporary loss of memory and cognition suggests some levels of awareness, and sleep disturbances typically imply cycles of consciousness and unconsciousness, which do not occur in a complete coma.