1x10 Asylum

Sam and Dean receive a tip from their father,
and travel to Rockford, Illinois, to investigate the haunted Roosevelt
Asylum, where criminally insane patients rioted in 1964. One of the
riot's victims was the chief psychiatrist (Norman Armour). The spirits
there try to communicate rather than attack, leading the brothers to
discover that the psychiatrist had been conducting cruel experiments on
his patients in order to test his theory that provoking extreme anger
would be therapeutic for them. The ghost of the doctor then confronts
Sam, causing him to lose his sanity and try to kill his brother. Dean
manages to subdue Sam and burn the doctor's corpse, stopping the spirit
and returning Sam to normal