The dark side of Robbie Williams

It is yet another bleak insight into the tormented psyche of Britain's most bankable pop star. On his 33rd birthday, Robbie Williams left the luxury of his Beverly Hills mansion to seek treatment for his addiction to prescription drugs in the austere setting of a rehab clinic - where all contact with the outside world is banned.

Since leaving Take That in 1995, fans have had periodic glimpses of the demons that trouble Robbie. The standard rock'n'roll litany of drugs have already sent the singer into rehab once and he has spoken on television of a battle with depression. His private life has involved reported relationships with singers Nicole Appleton, Geri Halliwell and Natalie Imbruglia. Another dalliance was with Rachel Hunter, the ex-wife of Rod Stewart.

Yet despite this apparent odyssey through the bedrooms of minor starlets across the world, Robbie complains about feeling lonely and jokes about marrying a girl from his native Stoke-on-Trent.

The cracks in that mental fragility were exposed again yesterday with a brief statement that Williams is once again seeking professional medical help. While publicists refused to disclose his location, Williams is widely believed to be at the exclusive Meadows clinic in Arizona, officially categorised as a level 1 psychiatric acute hospital. Residents pay 2,000 a night to undergo a life without alcohol, sugar, cigarettes and caffeine. The clinic's Spartan 12-step regime is designed to wean the wealthy from all sorts of substance abuse, even heroin.

While the prescription drugs referred to yesterday were not identified, Robbie has previously admitted to a heavy use of anti-depressants. While he professed to overcome the binge use of alcohol and cocaine that sent him into the Clouds rehab centre in Wiltshire after the Take That split, now anti-depressants appeared to have moved centre stage.

Robbie spoke of his use of the drugs in 2005, declaring: "I think my body might just be addicted to the medication."

The subject resurfaced again last weekend when American model Lisa D'Amato revealed her passionate affair with the rock star. D'Amato told the News of the World: "It was clear he [Robbie] was struggling with his mind. He doesn't drink but he needs anti-depressants to get him through the day. A lot of the time he seemed on edge."

Even while asleep, D'Amato said Williams seemingly could not find peace. "When he started shaking, I would gently lift him into my arms and rub his arms and legs until he stopped.

"He didn't wake up, but it seemed to calm him down." Not enough, it seems, to prop up the star's touring schedule. Robbie recently cancelled the Asia leg of his Close Encounters world tour, citing stress and exhaustion as the reason.

One of the frankest insights into the troubled mental universe of Robbie Williams came last year when the singer spoke of his battle with depression on a BBC documentary presented by Stephen Fry, a victim of bipolar depression.

Williams said: "My first drug of choice was probably fantasy. Fantasising about being an actor or being a singer, going to the moon, whatever. And I don't know if that was to escape a depression.

"With me, how my depression manifested itself was that I'd stop going out. I lost the cog to socialise.

"Having said that, I'd get up in front of 40,000 people and say, 'Look at me, I'm ace'. And then as soon as I got off stage, I'd get in the tour coach and go back to my bedroom and pull the duvet over my eyes."

Despite having signed one of the biggest recording deals in EMI's history - worth a reported 80 million - and selling more than 60 million records, Williams appears to have been unconvinced of his own talents. His hit songs Let Me Entertain You and Rock DJ reek of pastiche - in one, he dons the outrageous make-up of glam rock band Kiss, and in the second he strips himself bare in a controversial video, literally ripping chunks of flesh off. The gruesome video made headlines in America - alas one of the few occasions when Robbie has actually registered on the US music scene, despite his longing to make it big there.

Max Clifford, the publicist and former EMI press officer, described Williams as "a genuinely troubled individual".

He said: "If he's successful, he'll worry he won't be as successful, and if he's not successful, he will worry why not. You can't ever really see him finding peace, he appears to me to have a self-destructive nature."

With a fortune put at 100 million, Williams, a fantasy pin-up for countless women, could indulge any rock star whim. But instead, a picture emerges of a chain-smoking figure who often opts for solitude behind the walls of his home in Los Angeles, the city he moved to in 2002 as the base from where he would try and break America. So far, that ambition has failed to materialise. Some pronounce Robbie's self-mocking humour too British for American radio.

Whatever the reason, Williams is said to moodily pore over internet references to his career, becoming wounded by criticism.

The lacklustre sales of his latest album Rudebox , combined with the astonishing comeback of his old bandmates Take That, may have provided something to become morose about. Having split with songwriting partner Guy Chambers - the co-writer of Angels - in 2003, his form has been patchy of late. Rudebox, his seventh studio album, has struggled to spawn a hit single and has sold around half a million copies in the UK - nowhere close to the two-million plus sales enjoyed the first of his four solo records. By contrast, Take That's reunion record, Beautiful World, has sold more than 1.15 million copies. Such a reversal of fortune will be painfully underlined at tonight's Brit awards where Robbie - who has picked up eight of the music industry gongs - has, for the first time in a decade, not been nominated.

Phil Hall, a former News of the World editor, is cynical about the timing of the announcement over Robbie's treatment.

"I think it's a publicity tool.

If you're really that serious about it, just go and sort your demons out. You don't have to share it with everybody. The cameras are out there looking for the clinic now," he said.

It is unclear how long Robbie will spend in rehab, though one British expert on drug abuse last night warned that recovery from addiction to anti-depressants could take 12 to 18 months.

Pam Armstrong, a founder of the Council for Information on Tranquillisers and Anti-depressants, said: "People take anti-depressants because they are feeling low, but coming off them you often feel worse. It's really dependent on your metabolism rather than your personality."

Robbie has derided his cheeky chappie showbiz persona as "fake". His many fans will today be hoping that, at least his treatment will prove to be real.