I found the source of the actual quotation everyone has been citing in reference to Ledger and sleeping pills, even as the quote gets further and further from its source. It’s from a New York Times interview on November 4th:
He is here in London filming the latest episode of the “Batman” franchise, “The Dark Knight.” … It is a physically and mentally draining role — his Joker is a “psychopathic, mass-murdering, schizophrenic clown with zero empathy” he said cheerfully — and, as often happens when he throws himself into a part, he is not sleeping much.
“Last week I probably slept an average of two hours a night,” he said. “I couldn’t stop thinking. My body was exhausted, and my mind was still going.” One night he took an Ambien, which failed to work. He took a second one and fell into a stupor, only to wake up an hour later, his mind still racing.
What those who blame his insomnia on the aftermath of the Joker role are leaving out is the “as often happens” part of the quote. He had just been filming a Terry Gilliam movie in London before he died, so he was in the middle of a role again and thus having trouble sleeping.
The NYT story also has this ominous comparison from the director of I’m Not There:
“Dylan was completely inspired by James Dean, and Heath has a little bit of James Dean in him, even physically, a kind of precocious seriousness,” Mr. Haynes went on.
But I suppose you could find lots of “prescient quotations” about anyone after they die. Forunately most such comments never have the chance to become prescient.