Lenny Abrahamson’s drama Room impressed the critics and wowed audiences at this year’s Toronto International Film Festival, taking home the prestigious People's Choice Award. In the film Brie Larson stars as Ma, a woman being held captive in a room with her son Jack, in a role which required the actress to really get in the mind of someone cut off from the outside world.

Brie LarsonBrie Larson stars in Room.

For Larson, becoming Ma would take enormous mental and physical preparation which started with an intense diet and exercise program to get her inside the mind of someone being held in captivity. “That physical process really put me in a certain mindset,” Larson said.

“I felt more aggressive, more like a fighter, and at the same time I felt hungry and exhausted. It gave me a sense of what Ma must have felt like in her body after years in captivity with just barely enough food.”

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But to really get inside the head of Ma, Larson would have to limit her contact with the outside world, effectively becoming a recluse, only leaving her house to go to the gym. The actress said she believed Ma would have gone through waves of panic and acceptance while being trapped in the room, but mostly she was probably just bored by the routine and monotony.

Larson also spent time working with Dr. John Briere, a professor of psychiatry at USC and an expert in adolescent trauma to better understand both Ma and her son Jack. “What I learned from him is that in order to survive, when there’s too much going on in the world, the brain will shut off part of your awareness. So inside of Room Ma shuts off parts of herself to survive,” Larson explained.

Room is adapted from the book of the same name by Emma Donoghue, who also wrote the film’s screenplay. The author took a hands-on approach when it came to filming and was impressed with how Larson brought her character to life on the big screen.

“I’m so, so excited by what Brie has done with Ma,” Donoghue said. “I loved seeing her huge emotional range. She has many beautiful moments but she also wasn’t afraid to go to the dark side and go a bit mad.”

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Larson also used a little of her own experiences for the role, recalling when she first moved to Los Angeles with her mother and sister and the three lived in a small studio apartment. “We had very little money…Yet, there was something really simple and a little magical about that time. We still talk about it as one of the best times in our lives.”

“Of course, my experience wasn’t nearly as traumatic as what happens to Ma and Jack, but when I read the book, I connected with a child and mother going through a beautiful but painful time,” the actress added. Room opens in the US on limited release on October 16th, before being released nationwide on November 6th.

Watch the trailer for Room here: