In recent years the exploration of altered states of consciousness (ASCs) has intrigued scientist and nonscientist alike. These deviations from the normal conscious state have been produced by the ingestion of drugs, hypnosis, meditative techniques, religious practices, severe or prolonged physical or psychological stress, sensory isolation, sensory overload, and so on. All of these conditions can be mapped onto the arousal-level continuum. When this is done we see that altered states of consciousness usually are also altered states of arousal level. It would seem that when the patterning of input to the brain from internal and external stimuli is unusual, out of the ordinary, then the experience may be labeled an altered state.