Sinead O'Connor has cancelled her eagerly awaited tour, admitting that she's hardly in a place to perform. The drama-plagued singer, most popular for her '80s hit "Nothing Compares 2 U," has finally deemed herself too incompetent to tour. O'Connor announced the sad news about her deteriorating mental health via her Web site. She wrote, "With enormous regret I must announce that I have to cancel all touring for the year as am very unwell due to bipolar disorder. As you all know I had a very serious breakdown between December and March and I had been advised by my doctor not to go on tour but didn't want to 'fail' or let anyone down as the tour was already booked to coincide with album release."O'Connor concedes that she should have listened to her doctor, who warned her she was taking on too much. She adds, "So very stupidly I ignored his advice to my great detriment, attempting to be stronger than I actually am. I apologize sincerely for any difficulties this may cause. While touring will be cancelled I do hope and plan to appear at the Curtis Mayfield tribute in The Lincoln Centre in July." The disappointing announcement comes just a few months after the release of her new album How About I Be Me (And You Be You). So far, her latest work has received favorable reviews. It's been a rough go for the singer who contemplated suicide. She also struggled with her new marriage to Barry Herridge. The couple tied the knot, called it quits and then reunited. Hopefully, O'Connor will be able to find her happy place with the help of professionals.