It's a commonly–held belief that libido declines with age.

But a new study has revealed men are most randy at the age of 40 – dispelling the idea that sexual desire is highest in early adulthood.

Researchers from the University of Tartu in Estonia analysed data from more than 67,000 adults ranging in age from 20 to 84.

They discovered that male sexual appetite increased through their 20s, peaked in the early 40s and then began a gradual decline.

Remarkably, they found men in their 60s are just as horny as their 20–year–old counterparts.

Women, on the other hand, recorded a different trajectory. Their sexual desire really was highest in early adulthood – in their 20s to early 30s – but then declined with age and had a sharp drop after 50.

'A particularly notable finding is just how substantially higher men's sexual desire was compared to women's throughout most of the adult life span,' the researchers wrote in the journal Scientific Reports.

'While prior research has consistently shown that men report greater levels of sexual desire than women, our findings underscore the magnitude of this difference at different ages.'

The researchers said their finding with regards to men is unexpected – because it counters the idea that desire is primarily influenced by biology and fertility.

It is well documented that levels of the male sex hormone testosterone begin to fall from the early 30s onwards.

Despite this, the study indicates that male libido continues to rise for another 10 years or so.

'The mid–life peak in men suggests that factors beyond biological ageing, such as relational dynamics, may play a more significant role than initially anticipated,' the researchers wrote.

'For example, men in their forties are more likely to be in stable long–term relationships, which have been associated with increased sexual activity and emotional intimacy.'

Analysis also revealed that even the peak of female sexual desire at the ages of 20 to 30 was lower than men's average levels across much of adulthood.

It is only after the age of 60 than men's declining sexual appetite falls below the highest levels ever reported by women.

However, among both sexes there were huge differences between individuals – with some women reporting higher sexual desire than men.

The team also found that bisexual participants reported the highest levels of sexual desire.

While men in relationships reported higher libido than their single counterparts, single women reported more sexual desire than women who have partners.

Overall, participants who worked in office or sales jobs were the most randy, while machine drivers and those who worked in the military were the least.

Relationship satisfaction played a small role, as happier couples reported slightly higher desire.

For women, having more children was associated with lower sexual desire – but this effect was reversed in men.

'Sexual desire is a vital component of human relationships and well–being, shaped by demographic, relational, psychological, and cultural factors,' the team wrote.

'Understanding these influences is essential for advancing theoretical models and improving clinical interventions.'