Altered States

In this strange movie from 1980, abnormal psychologist Edward Jessup develops the theory (while studying schizophrenia) that our altered states of consciousness are just as real as our waking states. He tries to explore this theory by performing tests on himself and others using a sensory deprivation tank which can cause hallucinations. The experiments end when he moves away with his wife, thereby losing access to the tank.

The movie jumps into the future a few years, and he and his wife now have 2 daughters and are on the brink of divorce. Jessup hears of a tribe in Mexico that use hallucinatory drugs, and everyone has a shared hallucination. Still interested in his theory about altered states, he travels to mexico, participates in the ritual, and brings some of the drug back with him to the United States. He begins experimenting with the drug, and when that is not enough, he finds another sensory deprivation tank to push the experiment further. In one experiment he actually devolves into what appears to be an early hominid. In his final experiment witnessed by his wife and colleagues, he is transported back to a more primordial state and is rescued by his wife before disappearing altogether.

After this incident, while speaking to his wife, he begins to transform without the help of the tank or any drugs. He has to decide for himself which state he wants to live in.

This movie is much more interesting than I can make it sound, and its definitely worth the watch just for the psychedelic trip scenes. This movie is currently available to watch Hulu (free with monthly subscription).