Heh, hardly anything new. Marlon Brando has some really crazy stories about his 'process'
Dustin Hoffman has his wonderful "method" acting.
Fun moment of movie trivia, he had a big scene in Marathon Man that was shot on a Monday, he turned up looking awful, so much so that the Director and such almost called an ambulance for him, and they were asking him what was up. His reply was that since the scene was set after he'd been tortured and interrogated, he hadn't eaten, had kept himself awake, and had only had one or two glasses of water over the entire weekend.
Laurence Olivier, who was also on the film, got into conversation with Hoffman over this and was all "Why on earth did you put yourself through that?"
Hoffman was all "Well.. duh.. how else am I meant to do the scene?"
Olivier's dry reply was "Dear boy, why don't you just try acting?."