Not tonight, dear: Why MEN have been coming up with excuses to NOT have sex

So all the men who are losing their libido will have to come up with a different reason.

Experts are reporting a sharp rise in the number of husbands who have simply "gone off" passion.

They believe that the rising incidence of depression or our increasingly stressful working culture may be to blame.

Relationship counsellors report a 40 per cent increase in male clients admitting that, despite being physically able to have sex, they do not want to.

Peter Bell, head of practice at Relate, said: "Men used to come to us with impotence but Viagra has sorted some of that problem.

"What we have is a lot of men who say, as women did in the Fifties: "I can have sex, but I don't want to.

"It's not rewarding". Mr Bell said such complaints were unheard of ten years ago.

"They tend to be men in their thirties, forties and fifties and married," he said.

"It is a serious issue. It counts as a psychosexual dysfunction, rather than just a relationship problem, because these men haven't simply gone off their partner but off sex altogether."

One example is Billy, 43, a graphic designer from Newcastle-upon-Tyne who has been married for ten years.

He said his sexual desire had waned dramatically over the past three years.

"I still love my wife and am very clear that she's the woman I want to spend the rest of my life with but I just don't want to make love with her any more," he said.

"I don't fancy or fantasise about other women. It's just that, over the years, my desire to have sex with anyone at all has faded.

"It's true that I have a stressful job but previously sex helped me relax and forget my work problems.

"I'm baffled by my lack of interest, but not particularly unhappy."

Professor Michael King, of the Royal Free and University College Medical School in London, believes depression might be the problem.

Last week, he completed a study into mental illness across six countries which found the rate of major depression and panic syndrome was highest among men in Britain.

"Men are most likely to suffer depression between the ages of 30 and 50," he said.

"One of the explanations is that men are less able to talk about their problems than women, or express their emotions."

Professor Cary Cooper, president of the British Association of Counselling and Psychotherapy, added: "Britain's work culture has gone from nine to five to extremely long hours, which makes for a very stressful life.

"Stress can be cumulative, which means eventually people can find it impossible to switch off and relax."

Sales of make-up for men are booming, with bronzers, brow pencils, eyeliners and concealers

A spokesman for Harvey Nichols, which has just launched John Paul Gaultiers male make-up range, said this was a natural extension of the trend for male grooming products.

The men's toiletries market was worth an estimated £806million last year, up from £639million in 2002.

Lee Kynaston, grooming editor at Men's Health magazine, said products such as Clinique's M Cover stick, a concealer, had made men's make-up a mainstream product.

"Anything that can make you look better has to be worth investigating," he said.

But he urged users to employ a light hand, saying: "Men still want to be men, and women want men to look like men."