Directed by Ken Russell (1980, 104 min.). BluRay.
This exquisite horror/science fiction film is based on actual experiments conducted by John C. Lilly in the 1970s. The film follows a Harvard scientist named Eddie Jessup (William Hurt) who investigates the mysteries of human consciousness by taking hallucinogenic drugs while suspended in a sensory deprivation tank. Eddie is thrilled to find that while in this state, he can tap into the ancient knowledge of early Homo sapiens; but he begins to notice disturbing changes in his physique.