Altered States (1980)

In Altered States (1980), a scientist named Eddie Jessup begins experimenting with sensory deprivation tanks and ingesting powerful hallucinogens. As he delves deeper into his experiments, Eddie undergoes a bizarre and dangerous transformation, experiencing vivid hallucinations and regressing into a primitive caveman-like state. The film explores themes of evolution, the nature of human consciousness, and the boundaries of scientific exploration.