Any disorder of higher mental processes of such severity that judgments pertaining to the reality of external events are significantly impaired. A wide range of psychiatric, medical, and neurological conditions can bring about a psychotic state. They include schizophrenia, mania, depression, ingestion of drugs, withdrawal from drugs, liver or kidney failure, endocrine disorders, metabolic disorders, and Alzheimer's disease, epilepsy, and other neurologic dysfunctions. Not all psychotic states are caused by disease or drugs. The dreams of normal sleep are a form of psychosis; while dreaming, a reality can be seen and heard which, at the moment, is not known to be false but which is roused from upon awakening.