The share of American adults not having sex in the past year reached an all-time high in 2018, an intimate survey has revealed. Many of those missing out are men in their 20s.

An analysis of new research data by The Washington Post reveals a battle of the sexes, with 18 percent of the women between the ages of 18 and 30 reporting no sex in the past year along with 28 percent of men.

Male millennials are often portrayed in popular culture as the most sexually active - or at least the most sexually eager - and the news prompted a surprised reaction on social media.

The share of American adults not having sex in 2018 reached an all-time high in 2018

'Reasons why likely include a greater preference for video games and for porn,' tweeted US psychologist and practicing family doctor Leonard Sax, who was speaking generally about the issue before the survey's release.

'Young men tell me that the video games, and the porn, are vastly better today than they were 20 years ago.'

The portion of Americans 18 to 29 reporting no sex in the past year more than doubled between 2008 and 2018, to 23 percent.

The largest disparity is between age groups, with only seven percent of thirty-somethings reporting a barren year in the love stakes.

The figure is as impressive among frisky forty-somethings, of whom 91 percent had sex in 2018.

The portion of Americans 18 to 29 reporting no sex in the past year more than doubled between 2008 and 2018, to 23 percent

Among those those aged between 50 and 59, just 13 percent of this group say they didn't get lucky last year.

For those 60 and older, the share reporting 'no sex over the past year' has remained steady at around 50 percent.

But the overall 23 percent figure - up from 19 percent two decades ago - paints a picture of a nation growing gradually but steadily less amorous.

Jean Twenge, professor of psychology at San Diego State University said growing sexlessness among America's 20-somethings is primarily attributable to partnering up later in life.

Since 2008, the share of men younger than 30 reporting no sex has nearly tripled to 28 percent. There has only been an 8 percentage point increase reported among women

'There are more people in their twenties who don't have a live-in partner,' she said. 'So under those circumstances I think less sex is going to happen.'

Young men also are more likely to be living with their parents than young women.

'When you're living at home it's probably harder to bring sexual partners into your bedroom,' Twenge said.

Technology is also being seen as a factor. 'There are a lot more things to do at 10 o'clock at night now than there were 20 years ago,' Twenge said. 'Streaming video, social media, console games, everything else.'

Rates of no sex among adults over the age of 60 have consistently hovered around 50 per cent and are not shown here

Celibacy as a corrosive force hit the headlines recently with emergence of the 'incel' online subculture of angry young men unable to find sexual partners - with the movement linked to several mass shootings in the US.

But it has had its high-profile champions too: Andy Warhol, J Edgar Hoover, Isaac Newton and Joan of Arc were all said to be proud celibates.

The data on America's bedroom habits was collected for the General Social Survey conducted by the NORC research organization at the University of Chicago and analyzed by the Post.

The newspaper said its analysis underscored a three-decade trend line marked by an aging population and higher numbers of unattached people.