Brie Larson says she locked herself at home for a month - to get into character for 'Room' directed by Ireland's Lenny Abrahamson.

The actress - who won a Golden Globe and has been nominated for an Oscar for the role - says she wanted to see what happened if she isolated herself.

The film is about a mum and her son who are held captive for years.

And Brie says she made sure she had a lot of time with Jacob Tremblay - who plays her 5 year old son - before shooting started: