THE video, posted from a room in a Travelodge motel “in the arse-end of New Jersey”, was profoundly distressing.

The Irish singer songwriter Sinéad O’Connor, who in 2003 was diagnosed with bipolar disorder, had uploaded the 12-minute-long video to her Facebook page, and in it she discussed her mental health and alluding to suicidal thoughts.

“I hope that this video is somehow helpful”, she began, wiping away tears. “Not actually to me but the fact I know that I’m only one of millions of millions of millions of people in the world that are just like me, actually, that don’t have necessarily the resources that I have on my heart, or my purse, for that matter.”

She said she suffered from “three mental illnesses” and was all by herself, the only person in her life being her psychiatrist, “the sweetest man on earth, who says I’m his hero”.

Mental illness, she said, “was a bit like drugs – it doesn’t give a s**t who you are”. "People who suffer from mental illness are the most vulnerable people on Earth. We can’t take care of us. You've got to take care of us.”

Many of O’Connor’s fans immediately rallied to her support. The singer Annie Lennox, writing on Facebook, said: “I realise that Sinead has some serious mental health issues, but she appears to be completely out on a limb and I'm concerned for her safety ... It's terrible to see her in such a vulnerable state”.

However, in a statement posted on Facebook a few days later, O’Connor said she was well and was in a “wonderful, loving hospital … I have good people around me and I will never be lonely again. My mission from now on will be to dedicate my life to the abolishment of stigma toward mentally ill people and in particular to the abolishment of the abandonment of mentally ill people by their families”.

O’Connor, 50, has long been one of music’s most outspoken and confrontational artists, a fierce opponent of the Vatican’s attitude towards, amongst other issues, child sexual abuse. She once described the Vatican as a “nest of devils and a haven for criminals”.

She has been frank about her sexuality, about her personal relationships (she has had four marriages, and has four children and one grandchild). She has publicly chided Miley Cyrus for allowing herself to be “pimped”, after watching her revealing music videos.

Four years ago, Rolling Stone magazine included her in a list of '15 rock & roll rebels'. O'Connor, it said, “has made a career of kicking against establishment notions, starting with her trademark shaved head, a direct statement about the objectification of women”. The magazine said she once angered Frank Sinatra by refusing to perform at a venue in New Jersey if it played the National Anthem prior to the show. "I don't do anything in order to cause trouble," she said. "It just so happens that what I do naturally causes trouble." In 1999 she was ordained a priest by the breakaway Latin Tridentine church.

Amidst all of this, it is easy to forget just what a great singer she is - her Grammy-nominated second album, I Do Not Want What I Haven’t Got, released in 1990, brought her to widespread public attention, thanks largely to Nothing Compares 2U, an intense love song written by Prince. It was a huge hit and has been included in several polls of the greatest-ever songs or of all-time love/break-up songs.

Her third album, Am I Not Your Girl?, released in 1992, consisted of versions of songs that meant a great deal to her. But that October, on the US TV show Saturday Night Live, she tore up a photograph of Pope John Paul II while singing Bob Marley’s anti-racist song, War. “Fight the real enemy!” she declared, flinging the pieces at the camera.

It was said to be the single most controversial moment in the programme’s history, even though the TV audience was largely unaware that child abuse within the church was an actual issue.

Thirteen days after SNL, O’Connor was one of the stellar names guesting on a Bob Dylan 30th anniversary concert at Madison Square Garden. She was greeted by a cacophony of boos (and some cheers) and, upset but defiant, she roar-sang a few lines from War before walking off, the boos still ringing in her ears, to be comforted by Kris Kristofferson.

“I’m highly affected by sound”, she told Uncut magazine in March 2013, “and [the mixture of boos and cheers] was making me want to vomit. So, when Kris helped me offstage, I was trying to suppress the urge to vomit over him.” Her career took a long time to recover - which seems absurd given what we now know about paedophilia in the Catholic Church. In 2010, Pope Benedict issued a frank public apology to the victims of paedophile priests in Ireland.

If O’Connor has made headlines in recent years, it has largely been down to her personal issues and her statements on, for example, Cyrus, though there was a well-received album three years ago, called I’m Not Bossy, I’m the Boss.

In a typically forthright interview in 2010 she recalled that fateful episode on SNL. “The day I ripped up the picture of the pope”, she said, “was the best day of my life because then I became me. I could become the kind of artist I wanted to be. And now 99% of my life is rolling around the house and looking after the kids. I wouldn't go back to it for a million years."