This is something so unexpected! Mischa Barton under psychiatric hold in Cedar-Sinai!
I wonder what's happened to Mischa that needs this sorta medical attention!? She's obviously hit a rough patch!

Mischa was taken to hospital on Wednesday afternoon, after she called the police asking for medical help!
LAPD Officer April Harding confirmed to PEOPLE that they "assisted her with a medical issue and removed her from her home." But there were no paramedics were involved and no arrests were made.

The only explanation given for Mischa's state is that she's been "dealing with a lot of personal issues. I don't know if she really ever gave up some of the bad habits that had gotten out of control a couple years back", according to a pal of hers.

As to when Mischa will be released ... that's still unknown.

This isn't the first time Mischa gets hospitalized, she was hospitalized back in May 2007 after feeling ill at a friend's BBQ party, then six months later was arrested for DUI, marijuana possession and driving without a license.

We wish you a speedy recovery Mischa! Get Well Soon!