Altered States is a 1980 American science fiction-horror film adaptation of a novel by the same name by playwright and screenwriter Paddy Chayefsky. It was the only novel that Chayefsky ever wrote, as well as his final film. Both the novel and the film are based on John C. Lilly's sensory deprivation research conducted in isolation tanks under the influence of psychoactive drugs like ketamine and LSD.
Seeing this movie  for the it was very interesting.