Julianne Moore in film Maps to the Stars

"I do remember when I was starting acting, going from one set to the next, with not much else going on in my life. And at the end of the day you get back to your hotel room and just feel this awful loneliness, because the cameras have stopped rolling. If you ever want to have an existential moment, that's the time. You sit there and think, 'Who am I?'.

"But the only people who can affirm you are your family. They are the ones who are close to you. They're the only ones who can really see you."

As well as attending the premiere of Maps to the Stars at Cannes Film Festival this week, Moore is also currently promoting her role in the final two films in the Hunger Games franchise.

Both films have reportedly been re-written and re-ordered to compensate for the absence of Philip Seymour Hoffman who died from an overdose midway through production.

Speaking about the late actor, who she worked with on Boogie Nights, The Big Lebowski and Magnolia, Moore said, "It [Hoffman's sudden death] was a really horrible thing to happen. It's been so upsetting for all of us. We're all still trying to come to terms with it."

"It's like we were saying," the star continued. "People are mysterious. Anyone can speculate, but it's only speculation."

(Images: Rex Features)

Julianne Moore: "The longer you live the Hollywood lifestyle, the more empty you become"