The study finds that Americans who were married or living together had sex 16 fewer times per year in 2010-2014 compared to 2000-2004. The survey also found that overall, Americans had sex about nine fewer times per year in 2010-2014 compared to 1995-1999.
"These data show a major reversal from previous decades in terms of marriage and sex," said Jean M. Twenge, the study's lead author and professor of psychology at San Diego State University. "In the 1990s, married people had sex more times per year than never-married people, but by the mid-2000s that reversed, with the never-married having more sex."
Generation gap
Perhaps more surprising, younger consumers are having sex less often than older ones, said Twenge, author of the book "Generation Me."
In an earlier study, Twenge and co-authors Ryne Sherman at Florida Atlantic University and Brooke Wells at the Center for Human Sexuality Studies at Widener University, found that Millennials had fewer sexual partners than their Generation X predecessors.
"Despite their reputation for hooking up, Millennials and the generation after them (known as iGen or Generation Z) are actually having sex less often than their parents and grandparents did when they were young," said Twenge. "That's partially because fewer iGen'ers and Millennials have steady partners."
"Older and married people are having sex less often -- especially after 2000," Twenge said. "In a previous paper, we found that the happiness of adults over age 30 declined between 2000 and 2014. With less sex and less happiness, it's no wonder that American adults seem deeply dissatisfied these days."
So, are long hours at work to blame for Americans' declining libido? Twenge says no. In fact, those who worked more hours actually had sex more often, she said.
The study was published in the journal Archives of Sexual Behavior.