London: Check your age if you feel you have lost sex appeal among young women all of a sudden. Men who have turned 39 lose charm for young women as they are viewed more like father figures than sex symbols, a study reveals.

No chatting sessions or staying late at night to throw surprises was the top sign for younger women that a man has become "invisible".

"The most obvious sign of the change is when a man is no longer eyed up by women when he goes out," the survey by Crown Clinic, Manchester added.

Other signs included greying hair, double chin, thinning hair and having bad teeth.

In the survey, 52 percent of female respondents said men start to lose their allure to the opposite sex as they are about to turn 40.

Six out of 10 women assume that most men in their late 30s are attached by that age and are not worth approaching, the survey, published in Daily Mail, noted.