Altered States is a 1980 American science fiction horror film directed by Ken Russell, and adapted by playwright and screenwriter Paddy Chayefsky from his 1978 novel of the same name. The novel and the film are based in part on John C. Lilly's sensory deprivation research conducted in isolation tanks under the influence of psychoactive drugs like mescaline, ketamine, and LSD. The film features elements of both psychological horror and body horror.