The findings raise the possibility that conversations with friends about sex - plus reading all those sexual surveys in popular magazines - create a perception about how much sex you should be having. If you have more, the study's theory goes, you are more likely to be happier. If you have less, the reverse holds true.
However, the researcher pointed out that perceptions about sex vary, and so do reactions to it. "Obviously, we're dealing with statistical averages here," said study author Tim Wadsworth, an associate professor of sociology at the University of Colorado at Boulder. "I'm sure there are lots of people who aren't having any sex, and are leading incredibly happy lives."
And it's possible, although Wadsworth discounts the idea, that some other factor better explains the differences in happiness that seem to be linked to perceptions of keeping up with everyone else in the bedroom.
How the study was done
The study doesn't closely track people over a period of time, nor is it based on extensive personal details about their lives. Instead, it relies entirely on surveys of English-speaking adults in the United States from 1993 to 2006. The responses of more than 15 000 people were studied.
At issue: Do people's perceptions of their happiness as judged by survey responses (happy, pretty happy, not too happy) differ, depending on whether they're having as much sex as people similar to them do?
Wadsworth said he decided to study the question because previous research has indicated that getting richer doesn't contribute as much to happiness as people might think. Instead, as people get wealthier, they simply compare themselves to a wealthier group of peers and may still feel like they don't measure up.
The study found that the same thing happens with sex. The more sex people have, the happier they are. And if they think they're having more sex than people in their peer group are having - even if they don't actually know how much sex their friends and colleagues are having - their happiness goes up even more.
The study design relies on a complicated statistical analysis and doesn't allow the amount of differences in happiness to be expressed in simple terms. But the findings told the story: People who were having sex at least once a week were 44% more likely to report a higher level of happiness than those who had not had sex for a year. However, people who were having sex two to three times a month but believed their peers were doing it once a week were 14% less likely to report a higher level of happiness.
Is it possible that happy people just have more sex than their peers? That the happiness comes first and then (not surprisingly) more sex? Wadsworth believes his study debunks that possibility.
And how would you even know how much sex your peers are having, to develop more or less happiness by comparing yourself to them? Wadsworth said conversations about sex (especially among women) and certain magazines like Men's Health and Cosmopolitan give ideas.
What do findings really mean?
Andrew Oswald, a professor of economics at the University of Warwick in the United Kingdom who studies happiness, called the study interesting. "We know that humans care deeply about things like their relative income and relative body weight. Apparently those concerns extend to the bedroom as well," he said. "You just can't take the human out of humans."
However, he cautioned, "in all statistical studies of this kind, it is difficult to reach the standards of causal proof that would be produced by proper randomised controlled trials. I imagine that one day investigators will try to run such experiments, even in the sensitive area of sexual behaviour and human happiness, and it will be sensible for society to think through the ethical requirements for such research."
What to do with the findings?
"We tend to compare ourselves to people who are more successful than we are," Wadsworth said. "They tend to have a drain on people's sense of well-being. If we're aware of that process, it gives us some control over the emotional content of our lives."
The study appeared recently in the journal Social Indicators Research.
For more about sexual health, try the U.S. National Library of Medicine.