Mariah Carey has checked herself into a hospital for “extreme exhaustion,” her New York-based spokeswoman said Thursday. Cindi Berger would not specify Carey’s symptoms or the location of the hospital, but said that Carey’s active schedule contributed to her illness and hospitalization Wednesday night. “She’s been working around the clock,” Berger told The Associated Press. In a separate statement, the rep said: “Carey has been hospitalized for extreme exhaustion after completing two movies, ‘Glitter’ and ‘Wise Girls,’ and simultaneously writing, recording and producing her album, the soundtrack ‘Glitter.’ ” The singer has canceled all public appearances, including her performance at next week’s MTV 20th anniversary party in New York. Before Berger made Thursday’s announcement, Carey, 31, posted the following message on her Web site: “What I’d like to do is just a take a little break or at least get one night of sleep without someone popping up about a video . . . All I really want is to just be me and that’s what I should have done in the first place.” She also said, “I don’t say this much but guess what, I don’t take care of myself.” The message was removed from the site, and Berger said: “She was obviously very tired and not thinking clearly.”