- To be conscious, one must be both awake and alert.
- Patients who sustain severe anoxic cortical damage, with brainstem sparing, exhibit wakefulness and sleep, but are not aware, and thus, are unconscious.
- This description is the hallmark of a "vegetative state."
- A coma is a deep depression in the state of altered level of consciousness, which is characterized by the patient's response to verbal or painful stimuli.