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.

It marked the film debut of William Hurt and Drew Barrymore. Chayefsky withdrew from the project after disputes with Russell and took his name off the credits, substituting “Sidney Aaron,” his actual first and middle names.

The film score was composed by John Corigliano (with Christopher Keene conducting). The film was nominated for the Academy Awards for Best Original Score and Best Sound Mixing.