Mariah Carey thinks playing a dowdy social worker has boosted her self-confidence.

The singer - who is married to Nick Cannon and was previously wed to record company chief Tommy Mottola until 1997 - shed her glamorous image for her role in 'Precious: Based on the Novel Push by Sapphire' and says having to spend hours in front of a camera with heavy lighting and no make-up makes her feel more comfortable with staying natural at home.

She explained: "I think it was crucial to dress down. It was tough because making music videos is so different with the costumes, the angles, the lighting, stuff like that.

"In 'Precious', we sat in a fluorescent dentist's office and it was the worst-lit scene of the movie. The over-lighting emphasises the dark stuff under your eyes.

"I guess now I'll feel better about myself when I'm dressed normally at my house and walk past a mirror and see myself. I'll be like, well I've looked worse."

Mariah, 40, says she identified with the story of the movie - which follows a sexually abused, overweight teenager - because of her own previous experiences.

She explained: "The first relationship I was in, without realising it at the time, was abusive emotionally.

"That is in the past, but that helped me get to a place where I could grow and use that stuff in my work."