02/07/2008 at 01:50 PM EST
has entered rehab, a source close to the actress confirms to PEOPLE.
star is being treated at the exclusive Cirque Lodge Treatment Center in Utah, the same facility where Lindsay Lohan
spent nearly two months and where Eva Mendes
recently checked in,
according to the source.
"She's not doing well," the source says. "People were pushing her to go in there but there was no intervention… She has been partying hard for a while and I'm sure the Heath Ledger thing put people over the edge."
Adds the source, "She’s been crying a lot lately, a lot built up. …Everybody hits that bottom where you feel [so] scared that that one heavy night of partying can really wake you up. It's good she's getting herself help."
Dunst, 25, who is a regular on the party scene in Los Angeles, was recently seen partying at the Sundance Film Festival where she hung out with Josh Hartnett at Hyde Lounge. Despite reports of erratic behavior at the festival, sources say Dunst was just displaying her usual "care free party girl antics."
"She was in a big group of friends and they were dancing their asses off by their table. They looked like they were having a great time and they were getting pretty crazy," said a source at the time.
However, the following day Dunst failed show up to her own Glamour
magazine party. A source at the time said the actress "wasn’t feeling well."
A rep for Dunst could not be reached for comment.
The actress's stay in rehab was first reported by Star
Reporting by JED DREBEN and JENNIFER GARCIA