TORONTO -- Nicole Kidman says portraying traumatic experiences onscreen can take a toll on an actor.

Kidman stars in the new movie "The Goldfinch," which screens at the Toronto International Film Festival.

The drama follows a 13-year-old boy who manages to take a painting from the ruins of a museum bombing that kills his mother.

Kidman plays the matriarch of a family that takes in the boy after the bombing.

The Oscar-winning actress says she's recently been studying how the body and the mind process trauma, as many of the recent characters she's portrayed have dealt with distressing experiences.

Kidman, who portrayed a domestic abuse survivor in the HBO series "Big Little Lies," says that as an actor, trauma "becomes part of your life," and can be difficult to process.

"A lot of times when you're acting scenes that are very traumatic, your body doesn't know the difference... You take it on and you become that, and so much of it is then trying to shed that," Kidman said at a press conference for "The Goldfinch" Sunday, which has its world premiere at TIFF.

"It's something that I'm exploring, just as an actor with other actors right now, because how do you keep a lifetime of doing these sort of things -- because it's so important to be telling these stories -- but how do you actually stay healthy yourself, so that you can keep giving?"

Directed by John Crowley, "The Goldfinch" is based on Donna Tartt's sprawling novel, which won the Pulitzer Prize for fiction in 2014. It follows Theo, played by Ansel Elgort, through decades of personal suffering as he blames himself for his mother's death and turns to a life crime to hide the painting he stole, a small 17th-century masterpiece of a bird chained to its feeding box.

The movie also stars Oakes Fegley, Sarah Paulson and Luke Wilson. It opens in theatres on Sept. 13.