If Millennials really are having less sex, why would that be?

Dating apps such as Tinder and Bumble may have made "hooking up" (arranging sex) easier than ever but experts believe the generation traditionally associated with the most free and easy times – young people – are having far less fun under the covers than their parents' generation.

The phenomenon is acknowledged widely enough to have been dubbed the "sex recession".

The "Millennial sex recession" was first coined just over a year ago by American publication The Atlantic, which ran a feature highlighting an American study revealing young people born in the 1980s and '90s were more than twice as likely to report having no sexual partners as adults compared to people born in the 1960s and '70s.

Among those aged 20-24, 15 per cent reported having had no sexual partners since age 18, compared to 6 per cent of those born in the '60s and '70s.

Why might this be, when stigma around sex is lower than at any time in history? Most local experts in the field of youth sexual health and relationships say there has been one significant shift in a generation that is having the greatest impact on the amount of sex Millennials are having.

"If you compare them with a generation earlier, people in their 20s now are much less likely to be in a live-in, long-term relationship – or even married – than they were, and we know that the greatest predictor of how often you have sex is being in a long-term relationship," says Professor Juliet Richters, from The Kirby Institute, the lead investigator of the Second Australian Study of Health and Relationships (ASHR), published in 2014.

Even in the past decade, the ASHR survey of more than 20,000 Australians aged 16-69 found there had been a significant drop in the number of people in long-term relationships, with 74 per cent of respondents reporting they were in a regular or ongoing heterosexual relationship in the 2014 survey, compared to 87 per cent in the same survey published 10 years earlier.

Twenty-two-year-old legal editor Alannah Tommasoni says despite a widely held perception that the popularity of online dating apps equates to more sex, nothing could be further from the truth.

"It might mean more sexual partners, but not more sex. People my age are not having a lot of sex."

She is not surprised Millennials are in the midst of a "sex recession", claiming the move to online dating has meant casual sex and casual relationships have come at the expense of long-term relationships, and hence, more frequent sex.

"If I wanted to, I’m sure within five minutes on Tinder, I could find someone to spend the night with," Ms Tommasoni says. "It’s quite easy to find casual partners." But finding a "normal, long-term partner" is a completely different story.

People in their early 20s are not having as much sex because everyone is exhausted by the games. Nothing is simple anymore.

"Every guy I’ve dated in the past two years has turned around at one point and told me that he wanted to keep things casual. I’ve never been in a ‘normal relationship’," she says.

"People in their early 20s are not having as much sex because everyone is exhausted by the games. Nothing is simple anymore. We are currently in a period where body counts and options are more important than genuine connection," she explains.

Sydney-based sexologist Jacqueline Hellyer, who recently teamed up with Four Seasons Condoms on an initiative aimed at improving the sex lives of young adults, says in many ways "technology is working against young people when it comes to having quality relationships and quality sex lives".

"On the one hand, technology has enabled us to be more open about sex and have access to more information and to more people that we can meet, and we can watch people having sex, and some of that stuff is great … but that technology is also preventing some young people from making those real, quality human connections, where you can have quality sex and love making that is life enhancing," she says.

Ms Tommasoni says she currently has sex about once or twice a week, but that’s because she’s "settled into friends-with-benefits-type relationships".

"Before that, I would go through dry spells that would last months at a time."

She says while she would prefer to be in a "normal, long-term relationship", like many of her friends, she can’t find one.

"Most of us give in to what I call long-term casual relationships because that’s the only way to experience intimacy. I know so many women who put themselves through hell just to experience that, and it is not OK, and we know that, yet we still do it."

A’bidah, a 22-year-old university student who only wanted to give her first name, agrees that "being in a healthy, stable and sexually active long-term relationship seems like a privilege of some sort now".

"It’s easy to meet casual partners but I can’t say the same for long-term partners," she explains. "And casual sex isn’t that great so people don’t have it unless they really want or need to."

Experts, including Ms Hellyer, also believe the availability of online porn, as well as the proliferation of "picture-perfect" images on social media, means many young people are experiencing high levels of anxiety around body issues and sexual performance that may be preventing them from having sex.

Professor Meredith Temple-Smith, a sexual and reproductive health researcher at the University of Melbourne, wonders what impact the increase in the use of dating apps and social media is having not just on young people’s sex lives but also on their mental and emotional wellbeing as a result of their changed sex lives.

"Whether I can actually say we’re in a sex recession, I can’t … but I think there’s certainly a lot of reasons that make sex far more problematic," she says.

"I feel like there’s this big distance between public life and private life, which makes it more problematic, and sexual health can be both a cause and an outcome of mental health issues. I just don’t think we’ve teased out a lot of these things in terms of the behaviour changes we’ve seen over a generation and the impact it’s having on the mental health of our young people."