Sinead O'Connor said before being diagnosed with bipolar disorder, she struggled with thoughts of suicide and overwhelming fear.

She'd often wake up crying for no reason, the 40-year-old Irish singer said on Thursday's broadcast of "The Oprah Winfrey Show."

"It's like being a bucket with holes in it. Just leaking tears from every pore," said O'Connor, her closely cropped hair now gray.

O'Connor said she attempted suicide on her 33rd birthday, but gave no details. She was diagnosed nearly four years ago as having bipolar disorder, also known as manic-depression.

She now takes medications that serve as a mood stabilizer and antidepressant, as well as help her sleep.

The drugs have helped her become more balanced, she said, but "it's a work in progress. I'm not going to sit here and claim that I'm kinda perfect or anything. Anything is an improvement when you've been in desolation ... to be out of that place is brilliant. It doesn't mean you don't have lumps and bumps."

The medications also have provided a "scaffolding" to help her to work on recovering from abuse she suffered as a child, O'Connor said. She no longer thinks of suicide.

"I'm certainly out of despair, which is great."

O'Connor lives in Dublin, Ireland, with her four children. Earlier this year she released an album called "Theology," in which many of the lyrics are strongly influenced by the Bible.

Her breakthrough hit came in 1990, "Nothing Compares 2 U." She famously tore up a photo of Pope John Paul II during a 1992 appearance on NBC's "Saturday Night Live."

O'Connor told Winfrey she has sympathy for Britney Spears.

"She had two babies within the space of two years, (there) doesn't seem like a terrible amount of support from the people around her," O'Connor said.

O'Connor said it seems the media is constantly watching for Spears to make a mistake raising her children, but that no parents are perfect.

"I think to attack someone as a mother is very dangerous," she said. "I would say that's what puts a young girl on a precipice which is very, very dangerous, in my opinion. Some people may end up really regretting the way they're treating her."