Rosario Dawson - Rosario Dawson Thrilled By First Hypnotherapy Session

The Sin City star plays a hypnotherapist in the film and wanted to get a feel for her role by spending time with professionals so when one of them offered to put her under, she let down her guard and agreed.

She says, "I think it works actually, but I didn't have anything like cigarettes to quit or anything like that.

"I remember I went in and gave her (hypnotherapist) an idea of what I wanted to work on in the session and I laid down and she put a blanket over me because, when you go into a trance state, it's sort of like being in between sleep and awake, so your body thinks it's falling asleep.

"I relaxed and I went along with her voice and it was really comforting. My body did those little spasms that it does when you're falling asleep. Then, I woke up and she said, 'I know you said you wanted to work on this, but you reacted to this, this and this'. And I was like, 'How can you know all that?' And she said my foot was kicking when she asked me about a certain thing.

"It's actually quite interesting that your conscience will reveal itself, and if you're trained to read that, people give a lot of tells. It's almost like poker. We think we're hiding things, but we're not. It was really great for me to experience that, because the premise of the film is that hypnotherapy works on such a strong level. It was really necessary for me to believe that, and having been through that I gained a lot of respect for the profession, I have to say."

Dawson joined castmates James MCAvoy and Vincent Cassel and director and ex-boyfriend Danny Boyle on the red carpet for the London premiere of Trance on Tuesday (19Mar13).