Altered States is a 1980 American science-fiction horror film directed by Ken Russell based on the novel of the same name by playwright and screenwriter Paddy Chayefsky. The film was adapted from Chayefsky's only novel, published in 1978, and is his final screenplay. Both 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.