Men are viewed as father figures rather than sex symbols as they reach 39 even if their looks have not faded, according to a new study.
The research found that men start becoming 'invisible' sexually to younger women when they approach their 40s.
This was due to a number of factors - not all concerned with ageing, the 'Daily Express' reported.
According to the 1,000 people polled, the first flecks of grey hair and the emergence of a double chin are the biggest turn offs in older men.
The most obvious sign of the change is when a man is no longer eyed up by women when he goes out.
In the study, conducted by Crown Clinic in Manchester, over half of the people questioned said men start to loose their allure to the opposite sex as they approach 40.
However, it is not just a matter of age. Six out of 10 women assume that most men in their late 30s are attached by that age and are not worth approaching, the report said.
"Turning 40 is key turning point and it is the most popular age for men to seek a hair transplant," surgeon Asim Shahmalak from the Crown Clinic said.