Ledger told The New York Times in a November interview that he "stressed out a little too much'' during the Dylan film, and had trouble sleeping while portraying the Joker, whom he called a "psychopathic, mass-murdering, schizophrenic clown with zero empathy."
"Last week I probably slept an average of two hours a night," Ledger told the newspaper. "I couldn't stop thinking. My body was exhausted, and my mind was still going.'' He said he took two Ambien pills, which only worked for an hour, the paper said.