LAS VEGAS, NV - DECEMBER 03: Singer Britney Spears waves at a welcome ceremony as she celebrates the release of her new album "Britney Jean" and prepares for her two-year residency at Planet Hollywood Resort & Casino on December 3, 2013 in Las Vegas, Nevada. Spears' show "Britney: Piece of Me" will debut at the resort on December 27, 2013. (Photo by Ethan Miller/Getty Images)

UNSPECIFIED LOCATION - UNSPECIFIED DATE: In this handout photo provided by NBCUniversal, Britney Spears is pictured. Spears is the subject of the documentary "I Am Britney Jean" which details her personal and professional life. (Photo by Michelangelo Di Battista/Sony/RCA via Getty Images)

Pop princess Britney Spears has revealed the extent of her bipolar disorder and mood swings.

When she first exploded onto the scene in 1999, Britney (32) described herself as being carefree and a more sexualised version of herself.

But the Grammy winner says she's naturally shy and introverted and, and, as she gets older, is becoming more comfortable in her skin.

“I’m not really made for this industry,” she said.

"When I first started out I didn’t care what anyone thought of me, I was just happy to be there… then I started to realise there are a lot of mean things out there on the Internet,' she said.

In 2007, she suffered a very public breakdown, which she candidly reflects on in an E! News special 'I Am Britney Jean'.

"There was a time in my life when I couldn’t ever leave the house without 20 cars following me. I felt very alienated from the public. But as time passed, they lightened up and they kind of went away after I wouldn’t come out of the house for like two years.

"It was a very difficult time for me…I felt really alienated.

“This is all I’ve known all my life — cameras, being followed, being part of the industry.”

"I have always been kind of shy, since I was a little girl. It’s who I am to be modest, so I really can’t help it. I turn into this different person...seriously, bipolar disorder.

Her father Jamie is often by her side as a constant means of support, but she refuses to have him on the set while filming the sexier scenes of her music videos.

“There’s a saying you’re defined by who you become while you’re under pressure. And it’s true. It’s show business, and the show must go on.”

Online Editors