Decreased level of consciousness

An altered level of consciousness can result from a variety of factors, including alterations in the chemical environment of the brain (e.g. exposure to poisons or intoxicants), insufficient oxygen or blood flow in the brain, and excessive pressure within the skull. Prolonged unconsciousness is understood to be a sign of a medical emergency. A deficit in the level of consciousness suggests that both of the cerebral hemispheres or the reticular activating system have been injured. A decreased level of consciousness correlates to increased morbidity (sickness) and mortality (death). Thus it is a valuable measure of a patient's medical and neurological status. In fact, some sources consider level of consciousness to be one of the vital signs.