Heath Ledger's former lover has publicly paid tribute to the late actor for the first time.

Michelle Williams, who has a 2-year-old daughter Matilda with the "Brokeback Mountain" actor, has told Interview magazine his troubles with sleeping and his vulnerability.

The actress says, "He buzzed. He would jump out of bed. For as long as I'd known him, he had bouts with insomnia. He had too much energy. His mind was turning, turning, turning - always turning."

"He had a talent for everything that he put his mind to. He didn't know limits."

The former "Dawson's Creek" actress also reveals that beneath his hard exterior lies a sensitive person.

She continues, "You can pick it up on his performances, but it's easy to overlook because he was so physical and beautiful and strong and masculine. But there was always that underlying sensitivity. That's who he was."

Ledger died on January 22 at his Manhattan apartment. The cause of death was revealed in February as overdose of prescription drugs. The actor met Williams on the set of the award-winning drama "Brokeback Mountain." They separated in September last year.