"A few months ago I felt really low, really sad. Depressed for no reason," the 22-year-old actress-singer says in an interview in the February issue of Jane magazine, on newsstands Tuesday.
"I'm a very positive person, and I've always been glass-half-full," she continues. "So it was like someone flipped a switch in me. I wanted to figure out why."
Moore, newly single after high-profile relationships with actor Zach Braff and tennis standout Andy Roddick, says her recent split with Braff did not help matters.
"The breakup added to what I was going through, but it's not the complete reason," she tells the magazine. "It definitely doesn't help if you're already in that place ... ."
Moore, who is working on a new record at a studio in Woodstock, New York, and feeling better for doing it, says writing songs "away from friends in L.A. or New York" is good for the soul.
"Writing has been really therapeutic," she says of her music. "These little nuggets that have come up over the past eight months have made me look at things in a different way."
Moore started out as a squeaky-clean teen singer and later crossed over into movies with featured roles in such films as "A Walk to Remember," "Saved" and "American Dreamz."
"I feel bad that people wasted their money on such trite, blah pop music," says Moore about her earlier music, reports AP.
Moore has been looking inward a lot of late.
"I've been going through this really crazy time in my life it's what I imagine people fresh out of college go through," she says. "I'm asking myself life-altering questions, like `Who am I? Where do I fit in this world? What am I doing, what do I want to do? Am I living to my full potential?"'