Demi Moore Suffered an Apparent Seizure: Source

By Elizabeth Leonard and Dahvi Shira

01/25/2012 at 09:30 PM EST

Before Demi Moore was hospitalized, the actress "was having what seemed like seizures" at home, a source tells PEOPLE.

"Concerned friends called 911," the source says.

The actress, 49, is being treated for what her rep says is "exhaustion," as friends privately express concerns about her declining health and mounting stress.

While the cause of the reported seizure wasn't immediately known, a second source insists to PEOPLE that Moore "did not attempt suicide."

PHOTOS: Ashton & Demi: Portrait of a Marriage

TMZ, meanwhile, reports that Moore went to the hospital after a bad reaction to nitrous oxide.

Moore's reps have not commented since releasing the initial statement.

The former Ghost star, who has had a rocky couple of months that included a split from husband Ashton Kutcher and a death of a close friend, dropped out of her recently casted role as Gloria Steinem in the upcoming Lovelace film.

• Additional Reporting by LIZ McNEIL

RELATED: Inside Story: Demi Moore's Health Crisis