* Private Life: Ledger's personal life, especially his substance use, was a private matter. We don't have any public statements or confirmed information from him about his state of mind during filming.
* Method Acting: Ledger was known for his dedication to method acting, which involves immersing oneself deeply in the role. This often includes inhabiting the character's emotional and mental states, sometimes through unconventional means.
* Speculation: There have been many stories and rumors circulated about Ledger's preparation for the role, including claims that he isolated himself, kept a diary as the Joker, and experimented with certain substances to tap into the character's darkness.
* No Concrete Evidence: Despite speculation, there's no concrete evidence to confirm or deny whether Ledger used any substances during the filming of The Dark Knight.
Important Note: It's crucial to separate the role from the actor. Ledger's portrayal of the Joker is widely praised, but speculating about his personal life or potential substance use is disrespectful and unnecessary.
Instead of focusing on what might have happened, it's more valuable to appreciate the impact of his performance and the enduring legacy of his portrayal of the iconic villain.