The professionals closest to Heath Ledger have revealed how the Hollywood star battled with fame, a failed relationship and incurable insomnia in the lead-up to his untimely death.
Vocals coach Gerry Grennell worked and lived with the actor during the filming of the most recent Batman movie, The Dark Knight.
Ledger won a posthumous Oscar for his supporting role as The Joker in the movie.
Grennell says Ledger never once drank alcohol during that period but his use of sleeping medication to combat chronic insomnia was a concern.
"I'd say: 'If you can possibly bear it to stop taking the medications, do, because they don't seem to be doing you any good' - he agreed," Grennell told Vanity Fair magazine.
"It is very difficult for me to imagine how close he came to not taking them."
Vanity Fair spoke to the crew from Ledger's last film, The Imaginarium of Doctor Parnassus, and others for its August issue.
The Perth-born actor died in his New York apartment in January 2008 from an accidental overdose of prescription drugs.
He was 28.
Grennell is convinced Ledger's death, "was a combination of exhaustion, sleeping medication ... and perhaps the after-effects of the flu".
Cinematographer Nicola Pecorini worked with Ledger on Parnassus and said he dabbled in minor narcotics but dropped the habit.
"He used to smoke marijuana on a regular basis, like probably 50 per cent of Americans (but Ledger) went clean as a whistle," Pecorini said.
The actor's mentor and Parnassus director Terry Gilliam said Ledger's romance with Michelle Williams began to unravel during the Oscar campaign for his acclaimed performance in Brokeback Mountain.
Williams is the mother of their three-year-old daughter Mathilda.
Legal wrangling over custody of their daughter "made Heath snap", Gilliam said.
The strife coincided with the Parnassus shoot and brought on the beginning of pneumonia, Gilliam said, but Ledger would not heed doctor's advice to take antibiotics and rest.
Gilliam said Ledger responded: "'No way - I'm not going to go home because I can't sleep and I'll be just thinking about the situation. I'd rather stay here and work".
"He would arrive (to the set) in the morning completely knackered," Gilliam said.
"By the end of the day he was beaming - glowing with energy.
"It was like everything was put into the work because that was the joy - that's what he loved to do."
The actor's friend and agent Steven Alexander said Ledger was never motivated by money or stardom and was worried that his role in a "summer blockbuster" such as The Dark Knight would typecast him.
"He was ready to bust out of the gate but he didn't want to step on the gas and become something that he didn't want to become - a matinee idol," Alexander said.
"He wasn't motivated by money or stardom but by the respect of his peers (and moviegoers).
"He was striving to become an 'illusionist' as he called it - able to create characters that weren't there."
The August issue of Vanity Fair is due to hit news stands in early July.