Actress Michelle Williams is suffering sleepless nights as she makes her Broadway debut in a new revival of Cabaret, confessing she accepted the job without "thinking things through". The Brokeback Mountain star admits she has a tendency to act on impulse and jumped at the chance to take on the all-singing, all-dancing role of Sally Bowles, a part made famous by Liza Minnelli in the 1972 film adaptation of the production, but the shy actress failed to consider how nervous she would be performing in front of a live audience night after night. She tells the New York Times, "I'm still losing sleep. I don't think it's apprehension. I wanted to do this from the minute I heard about it. It's just the unknown." Williams adds, "I've realised something about myself. When I said I wanted to do this, not a few people in my life said, 'Are you sure? Aren't you going to be terrified?' I'm not good at thinking things through. I get excited about something, and that outweighs everything else. I don't really carry the vision down the line to see the possibilities of how it might turn out. "I think that for my work, that's actually been an OK trait. For life, not so good." Cabaret, which also features the return of Alan Cumming in his Tony Award-winning role as the Emcee, is co-directed by Sam Mendes and choreographer Rob Marshall. It began previews on 21 March (14) and opens at New York's Stage 54 later this month (24Apr14).