Exclusive: Blair's spin-doctor reveals his battle with depression while at No 10, and his 'nightmare' over the suicide of Dr David Kelly

Alastair Campbell, one of the chief architects of New Labour and Tony Blair's trusted communications chief, has revealed for the first time the depths of his struggle with depression - and how he suffered bouts throughout his time working at Downing Street.

In an exclusive interview with The Independent on Sunday, Mr Campbell reveals how he told the Prime Minister about his mental health problems. He talks about the "nightmare" impact of the Hutton inquiry, how the death of Dr David Kelly was his "worst day" - and how his experience of a crippling breakdown in his 20s helped him to cope. He said: "It [the Hutton saga] was one of those episodes where things spiralled out of control... I felt completely confident in relation to the facts but during the whole period it was a nightmare. And you are thinking, 'There's this guy for whom it's been such a nightmare he's killed himself'."

He has chosen to give a frank account of living with depression, ahead of World Mental Health Day this week, to highlight the stigma faced by sufferers of mental illness. It also follows the revelation by David Blunkett this weekend that the former home secretary suffered clinical depression as a result of his affair with Kimberly Quinn.

On Tuesday, Mr Campbell will make his first major public speech on mental health at the Mental Health Media Awards in London, where he is expected to highlight "the worrying" association between violence and mental illness by some sections of the press.

One in four of the UK population will be affected by depression at some point. But the World Health Organisation is warning that depression and mental health problems will be the second-biggest disease burden by 2020.

Mr Campbell, who has three children, says depression should be properly recognised as an illness and openly talked about like "a broken leg".

"There is a lot of stuff in the media which quite frankly doesn't matter a damn. But this area [mental health] does have an impact on how people are treated. The most worrying thing is the constant association between violence and mental illness. Mental illness is not just about risk or violence. It's about all of us."

At times, Mr Campbell says, he was so depressed that "you wake up and can't open your eyes, you can't find the energy to brush your teeth, the phone rings and you stare at it endlessly". He tells how, while head of communications at No 10, work was a deliberate distraction from his lows, but that he missed one media briefing because his illness left him unable to "face doing it".

His earlier collapse, while news editor on a national newspaper, he describes as "a work-induced, drink-induced, pressure-induced psychotic breakdown", which made him face up to his excessive drinking and helped him to quit. This breakdown also gave him the strength to cope with seven years in Downing Street. He credits his recovery to the support of Mr Blair, his own family and his "brilliant" doctor. Others, he says, are not so fortunate.