Happy now: Has Sinead O'Connor finally put her pain behind her?

The singer is about to release her first 'joyous' album, '4th and Vine', says Nick Duerden.

Sinead O'Connor is telling me that, as a child, she could run like the wind. "I was fast, a great sprinter: 100m in 11.3 seconds." This sounds pretty fast to me, and later I check out her time online to learn that perhaps only a dozen or so women have ever run faster. It seems she had an incentive to be quite so quick on her feet, though. "I was a kleptomaniac. I needed to be fast in order to avoid the cops." And why was she stealing? "It was part of how I avoided abuse at home."

O'Connor's mother – who would die in a car crash when Sinead was 19 – was a troubled, violent woman, and was also, the singer says now, a kleptomaniac herself who required her children to behave similarly. "She used to go to houses that were for sale just so she could rob shit out of them. I suppose it was funny, in a way, without being funny at all. You know, she'd go to hospitals and nick the crucifixes off the wall. She couldn't help herself, God rest her soul. It was an illness. And so that was part of what was going on at home: I'd steal to pacify her."

She may have been quick, but 11.3 seconds doesn't outrun a police car. She was arrested many times, and sent to social workers who eventually recommended a correctional facility run by the local church. It was here that she met a nun who bucked the typical stereotype by actually being sympathetic to her vulnerable young charge. "Oh, she was very cool. She knew I loved music, and encouraged me in it."

The sympathetic nun later bought O'Connor her first guitar, which gave her things other than stealing to do, and soon she was busking on the streets of Dublin. By 14, she was singing with local bands, and seven years later she would release her first album: 1987's The Lion and the Cobra was a fascinating record, vivid and hypnotic, and sinister in a most becoming way. Given what was to follow, it was the perfect introduction.

"I suppose I've got to say that music saved me," she says, mug of what I think is herbal tea in one hand, fag in the other. "I didn't have any other abilities, and there was no learning support for girls like me, not in Ireland at that time. It was either jail or music. I got lucky."

It's 11 o'clock on a late December morning, at the north-west London house of John Reynolds, O'Connor's manager and producer (and father of her first child, Jake, now 25). I'm in the kitchen trying not to be intimidated by her two beautiful but enormous Great Danes when she enters. She smiles hesitantly, and delivers a handshake that would impress a wrestler. Twenty-five years after she first emerged into national consciousness, a spectral beauty with a voice to match, she remains a striking presence, all the way down to her clumpy steel-toecapped boots. Now 46, she still sports a shaved head and still lives in Ireland [in a house overlooking the sea at Bray, just outside Dublin]. In the flesh, she's tiny, and looks, as she always has, at once vulnerable and entirely indomitable. The sleeves of her black shirt are rolled up to reveal tattoos on her arms, and sufficiently unbuttoned at the chest to show off an inky Jesus Christ across her breastbone.

She touches it fondly. "I've got a bunch of religious shit all over my body: Rasta, Catholic, Hindu, Muslim, Jewish. I don't necessarily like to flash them too much. They're more to focus me artistically."

She remains devoutly spiritual, even though she readily concedes that "God", these days, is such an offputting word. "But it doesn't have to be. It really doesn't." She flashes another cautious smile. "Anyway, shall we go upstairs?" And with that, she leads me up to the attic studio, to talk more.

One doesn't approach an interview with Sinead O'Connor the way one would any other pop star, and certainly not if you had bothered to bone up on your subject beforehand. She can all too often seem, on paper, a most complicated woman: driven, obstinate, cripplingly shy yet wildly verbose, and interviews read like torturous affairs, a duel in which no one emerges the victor. But this isn't the O'Connor I encounter today. At first she is guarded, certainly, but with each successive cigarette – and she smokes the way she talks: quickly, urgently, without pause – she unwinds a little more, and that tentative smile begins gradually to reach her eyes. When she laughs, she looks purely mischievous. She speaks in a lower register than her singing voice, often invoking the word of God, and using "fuck" more for purposes of punctuation than to express anger. And small talk, you quickly realise, is entirely superfluous in a woman so comfortable on the bigger subjects.

"Sorry if I'm terribly long-winded," she laughs at one point. "I can't help myself. Don't be afraid to shut me up."

She has had, by anybody's standards, a tumultuous time of late. Throughout the promotion of her current album How About I Be Me (And You Be You?), her bipolar disorder has been endlessly raked over and frequently misinterpreted, the depression it caused her worsening gravely after her fourth marriage ended in December 2011, and prompting her, perhaps unwisely, to tweet that she was considering suicide. When she later appeared on The Graham Norton Show to plug her unambiguously joyful single "The Wolf is Getting Married", she winced as the host enquired after her wellbeing when all she wanted to focus on was the music. But focusing solely on the music has always been difficult with Sinead O'Connor. Her music is her life, just as her life is her music. It all gets muddled up in there together. It's what makes both everything she sings, and also everything she says, so unusually compelling.

"Yeah, but it has a pretty negative effect on me," she complains. "I do interviews these days, and people tell me that they were frightened to meet me. I find that frightening in itself."

And so she recently took to her website to explain her condition. "The poor interviewers are devoid of vital information needed in order to steady themselves and not feel the need to hover near the alarm button," she writes in her introduction, and then, over the next 1,500 words, attempts to allay any lingering fears people might have that she is crazy. She isn't. She was diagnosed as bipolar back in 2005 after a traumatic event that she refuses to discuss. There are two types of bipolar disorder: the manic type, and the depressive. She suffers from the latter, hence the occasional suicidal lows.

"I've had this for seven years now, but people have been treating me like I was mental ever since I ripped up a picture of the Pope on American television [in 1992]. It's been wounding and upsetting; it means facing a lot of prejudice. And it's unfair. You wouldn't abuse somebody with a broken leg by calling them a broken-legged cunt, would you?"

She fetches another cigarette out of its packet, and squeezes the filter between finger and thumb before putting it into her mouth, lighting it, and inhaling. "But, hey, it's getting better. It is. People aren't calling me a fucking wanker so much any more, so that's a good thing, right? Perhaps it's because I've made a happy album at last. I guess that's helped."

her 1987 debut established her as a cult artist, her next album, 1990's I Do Not Want What I Haven't Got, unwittingly promoted her into popstar territory. It may have been similarly imbued with the kind of rage O'Connor did so well – parcelling up songs that dealt with abortion, abuse, divorce and racism in very pretty packages – but it also featured a cover version of a little-known Prince song called "Nothing Compares 2 U", which went to number one all over the world. She did not deal with the attention well.

"I was ill," she notes. "I wasn't happy."

Still dealing with the fallout from her upbringing, which she chose to air publicly, and enraged at the Catholic Church, whom she suspected of covering up widespread cases of child abuse, she elected to use her moment in the spotlight to vent such frustrations with the kind of mettle that would come to define her. The tearing up of the picture of the Pope on Saturday Night Live in front of millions of horrified Americans was just the tip of the iceberg. A geniune protest singer in an era of shiny happy popstars and disaffected grunge icons, she was vilified accordingly.

Though she released three further albums in the 1990s full of lovely, affecting songs, her commercial appeal nosedived, and by the early 2000s, she had effectively become a self-imposed niche artist, releasing albums comprised of traditional Irish folk songs, reggae songs and songs based around scripture from the Old Testament. Her private life, meanwhile, was consistently eventful: she now had four children with four different men, and had been divorced four times. On more than one occasion did she announce her retirement from the music industry; she declared herself a lesbian (later retracted); and was even ordained as a Catholic priest. Which is perhaps why her most recent album was welcomed with such unexpected surprise. How About I Be Me (And You Be You?) is classic O'Connor, but it's accessible, too. It's also happy and inclusive.

"Previously," she says, "I had always written music from a point of pain and healing. I needed to get all that shit out of me, which I did, slowly. That's why this new record is very different. It's not as introspective. It's me having come out the other side."

In the summer of 2011, O'Connor wrote an article for the Irish Independent newspaper on how lonely she was. "My situation sexually/affectionately speaking is so dire that inanimate objects are starting to look good," she wrote. It was supposed to be a light-hearted piece, and though she drew much criticism for baring her soul in this fashion, it prompted her into online dating, and she bagged herself a man. His name was Barry Herridge. They fell quickly in love, and married six months later in Las Vegas. According to subsequent reports, the marriage lasted less than a month.

"Not because it wasn't a good relationship," she points out, "because actually it was, it was a great relationship, the only one of my four marriages I'd say I went into for the right reasons, but because so many people put so much pressure on him. I've always been a target for the press in Ireland, and so unfortunately have my loved ones."

Herridge was a drug counsellor for young people, and because it was known that O'Connor occasionally smoked pot, the Irish media suggested that he was no longer qualified to do his job. "Ultimately, they tried to destroy him. It became impossible to have a normal life."

You could argue, of course, that O'Connor knows full well the potency of her fame, and so why on earth did she go down so public a route on such a private matter.

Her answer comes in two parts, the first with a smile on her face. "I'm a closet exhibitionist," she shrugs.

The second comes with a frown. "Look, I refuse to let my job dictate how I have to behave. I've every right to be as lunatic in my behaviour as the lunatic next door, no? I've no regrets."

But it does mean that she continues to be treated by the Irish press in much the same way that Katie Price is treated over here. Why doesn't she just leave?

"I don't leave because I have children with men who still live there," she says. "And their needs come first. But otherwise, I'd leave immediately. I absolutely fucking hate it there. OK, sure, it's a safer environment for younger children than it is perhaps in London, but at least in London you can be anybody you want, and nobody takes any notice of you. In Ireland, I cannot be an ordinary person. Everybody wants something of me, everybody has their fucking opinion. It's exhausting."

She shrugs, then leans forward to extinguish another cigarette, squashing it into the wastepaper basket with more effort, strictly speaking, than the cigarette requires. Our time up, we walk back downstairs to the living-room, and the dogs. Before I leave, she recounts a dream she has had more than once.

"I'm in a lift with singers like Van Morrison and Eric Clapton, a few others, all fellas. We reach one floor, and the door opens. It's raining. They all get out, then turn to me and ask whether I'm coming. But I smile and say, 'No, I'm getting out on the sunny floor.'"

An optimistic dream, then, and she thinks she may almost be there, on the sunny floor, at last. Music, she tells me, has been a rope throughout her life, one that she has clung on to during a disproportionate amount of bad events of which, contrary to what some may think, she hasn't always been the sole architect.

"It's been a journey, but I feel that I've completed it, I'm healed, and I'm starting out on a new one. When I leave my life as an old lady, I hope that each successive record will have shown me more and more at peace, and more and more joyous."

She reflects on the unusual word she has just uttered – joyous – as if savouring it. Then she laughs.

"That's the idea, anyway."

Sinead O'Connor's new single, '4th and Vine', is released on 28 January. She plays the Elgar Room at the Royal Albert Hall on 15 February, and the Barbican on 27 March. For more information: sineadoconnor.com