Demi Moore 'grew' as an actor filming The Substance

Demi Moore "grew" as an actor and a person shooting her new horror The Substance.

In the upcoming body horror, the Ghost actress plays Elisabeth Sparkle, a fading Hollywood star who undergoes an experimental medical procedure to produce a better, younger version of herself, played by Margaret Qualley.

The Substance marks Moore's return as a lead actress after years of smaller roles and she revealed to IndieWire that the project helped reinvigorate her love of acting.

"What I love is this was a rich, complex, demanding role that gave me an opportunity to really push myself outside of my comfort zone, and in the end to feel like I explored and grew not only as an actor, but as a person," she said.

"I feel like I took a real step back for a long time and really questioned even whether or not this is what I should be doing. This was a part of waking myself up."

The 61-year-old admitted signing up for Coralie Fargeat's gory movie was a "risk" but it paid off when the film received a rapturous reception when it premiered at the Cannes Film Festival in May.

"As you can see from watching it, starting with it on paper, it felt risky. It was one (where) you don't know if it's going to all come together or work," she confessed. "It's what you hope. And so, in all honesty, I think I'm still feeling a little bit of shock, awe. I feel extremely humbled by the overall experience."

The St. Elmo's Fire star also revealed that she spent anywhere from six to nine hours in the make-up chair being covered in prosthetics to depict Elisabeth's physical decline towards the end of the film.

"It is a very big commitment and I have a huge respect for people who've taken on roles where the entire movie from start to finish is prosthetics," she added.

The Substance will be released later this year.