Gordon Brown may well be proud of his workaholic reputation but not all of his ministers feel the same way.

And yesterday, perhaps believing she was acting in his best interests, Hazel Blears advised the Prime Minister to get out and have a "bit of fun".

The Communities Secretary was responding to a report that Mr Brown had been surviving on two or three hours of sleep a night and was increasingly "exhausted".

Suggestions that lights are seen in his study until 2am or 3am, only for him to be back at his desk at 5am, were dismissed by Downing Street sources.

Asked by the BBC's Andrew Marr if it was true that Mr Brown was "shattered and ratty", Miss Blears replied: "He's certainly not ratty."

But he did "work hard" and was under "stresses and strains".

Challenged on whether she thought he was working too hard, Miss Blears added: "Well, at Christmas I was delighted when he took two weeks off, had a holiday with his family.

"I think it helps all of us as politicians. You know, we're not super-human and we get tired.

"And I think it helps all of us if we have a bit of a break.

"And I think a balance in a politician's life, a bit of fun as well as a bit of hard work, is probably the best place to be."

Mr Brown's summer holiday in Dorset lasted just four hours. It was cut short when he returned to London to deal with the foot and mouth crisis.

Later, he visited his Scottish constituency with his family.

Professor Cary Cooper, head of psychology and health at Lancaster University, said Mr Brown's personality type meant he was driven and ambitious.

He added: "It's very difficult for these people to relax.

"But in the long run, when they are under a lot of pressure, they do tend to be fairly stress-prone.

"I suspect Mr Brown's Scottish Presbyterian background also means he believes that to achieve, you have to work hard.

"But no matter how robust you are, and how guilty you feel about taking time off, everyone needs a break."

Downing Street said Mr Brown was "relaxed" about Miss Blears's remarks.