Best known for playing the rebellious Marissa Cooper on the highly popular teen drama "The O.C.," actress Mischa Barton had her own share of struggles under the spotlight, and recently opened to up to People magazine about her "Hollywood nightmare" breakdown.

The 17-year-old quickly rose to fame and became one of Hollywood's "it" girls in 2003, but behind-the-scenes, her partying and personal issues were getting out of control.

In 2007, she was arrested for a DUI, marijuana possession and driving without a license, and after pleading no contest, was sentenced to three years of unsupervised probation in 2008.

After her parents attempted an intervention in 2009, Barton blacked out under the influence of sedatives and was consequently placed on a 5150 psychiatric hold after she threatened suicide. The star was admitted to the Cedars-Sinai Medical Center under the involuntary hold, an event she refers to as a "full-on breakdown."

Previously, the star had blamed her hospitalization on a "terrible wisdom tooth surgery," but now it seems she's more willing to open about her struggles.

"I was under enormous pressure," Barton told People. The star was under constant media criticism for her weight. "It was always, 'She's too skinny, she must be sick,'" she said. "Then it was, 'She's too big.' I was never the right weight."

Now the 27-year-old is focused on staying healthy and working on a host of new projects, including the new thriller "I Will Follow You Into the Dark," "Apartment 1303," and a new television pilot, "The Gutsy Frog" with Frankie Jonas. She's also working on her makeup collection and handbag line, and is spending plenty of time delving into the world of fashion while working with her London boutique to create new styles.

"I've learned a lot," she said, adding that she's proud of where she is today and being able to speak out. "I'm stronger now."

You can read more about Barton's breakdown when her cover issue of People hits stands this Friday, Oct. 18.