The actor, who separated from wife Courteney Cox in October, has entered a rehab program, his rep confirms to PEOPLE.
The rep had "no further information," however a source says the actor needs help with alcohol and other issues.
"He is in there for drinking and depression, not hard drugs. Rehab was inevitable," says the source. "He is dealing with a broken heart. He can't handle all the changes in his life. All his inner demons came out."
During a recent interview on Howard Stern's radio show, Arquette, 39, said that his psychologist, whom he sees once a week, believed he was having a "nervous breakdown," and the actor confessed he'd been "drinking a lot."
"Everybody's worried and concerned about me," he added during the interview. "When I drink, I become a maniac."
A source told PEOPLE recently that Arquette, who is dad to 6-year-daugher Coco with Cox, 46, was having trouble managing the separation.
"He's just not handling this situation well," the source said. "He's really depressed.
TMZ.com first reported that Arquette had entered rehab.