Sensory deprivation

Sensory deprivation is a condition in which a human being (as well as many extraterrestrial races) is denied access to one or more of the five primary senses, taste, touch, sight, smell and hearing. Sensory deprivation rarely occurs in nature and is usually artificially generated for purposes of conditioning or torture. Military organizations may employ sensory deprivation tanks in which an individual is subjected to an extreme lack of external stimuli in order to better prepare them for functionality in an adverse environment.

Examples in fiction
In the pilot episode of the 1959-1964 anthology television series The Twilight Zone, an Air Force officer named Mike Ferris was placed into a sensory deprivation chamber to test his resolve for the physical rigors of operating in a zero-G environment on a planned space journey to Earth's moon. Extreme sensory deprivation caused Ferris to hallucinate and he imagined himself trapped in a world where he was the last surviving human being on the planet Earth. (TZ: Where Is Everybody?)