Which 1980 movie is about an emotionally-obsessed scientist who experiments on himself?

The 1980 movie about an emotionally obsessed scientist who experiments on himself is Altered States.

William Hurt plays Edward Jessup, a brilliant but troubled scientist researching altered consciousness. He combines sensory-deprivation experiments in an isolation tank with a powerful psychoactive substance obtained during fieldwork, hoping to reach deeper or more primitive states of human awareness.

The experiments become increasingly dangerous and literal: Jessup experiences hallucinations, visions of early human forms, and apparent physical regression. His research is driven not only by scientific curiosity but also by emotional turmoil, including the breakdown of his marriage and his determination to discover what lies beneath ordinary human identity.

Directed by Ken Russell, the film was adapted from Paddy Chayefsky's novel and inspired in part by the real sensory-deprivation research of John C. Lilly. It is often remembered for its surreal imagery, experimental tone, and unusual blend of science fiction, horror, and psychological drama.