Ellen Burstyn: my biggest challenge

When I first read Requiem For A Dream I wasn't interested in it.

I thought, "Oh my goodness, these people are in such trouble, every character is in hell." Plus, it was a low-budget film and they wanted me to do it for hardly any money.

I'd heard about Pi, the director Darren Aronofsky's first film, but hadn't seen it. So I thought before I turned down Requiem, I'd take a look at Pi. I saw two minutes and knew this guy really was an artist - that I'd better work with him. And I'm glad I did - he's a visionary. I really like the film.

What impressed me about the writing was the way the author Hubert Selby Jnr had such compassion for characters hooked into the American Dream. He's saying that these dreams can be poisonous - they can stop you dealing with your life as it really is. He's talking about how you're always trying to escape into that never-never land, which is itself a narcotic.

In Requiem For A Dream I play a lonely Coney Island widow, Sara Goldfarb, who becomes addicted to diet pills. I don't think I've ever been this challenged in a role - it was harder than The Exorcist.

Darren has the most complicated and complex use of camera and rigging technique that I've ever seen. Sometimes I had to spend four hours in the morning being fitted with prosthetics - I had four different necks, two different fat suits and nine wigs. But it never occurred to me to worry about how I looked in this film. It's not that I'm vanity-free, it's just that my vanity is in my work and not in my looks.