A Group of Couples Started Having More Sex, and It Made Them Less Happy

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30th October 1954:  A couple in a failed marriage lie back to back on their bed. Original Publication: Picture Post - 7373 - Why Marriage Can Fail - pub. 1954  (Photo by Thurston Hopkins/Picture Post/Getty Images)
Photo: Thurston Hopkins/Picture Post/Getty Images

Psychologists have long been confronted with a sexy, sexy mystery. On the one hand, there’s a long-standing correlation between sexual frequency and happiness for both couples and people — all things being equal, the more sex someone has, the happier and the more satisfied with their relationship they are. On the other hand, this notion comes from correlational studies, so it’s not clear that having more sex causes an increase in happiness. Maybe being happier causes couples to have more sex, or maybe there are other variables that cause an increase in both sex and happiness, or maybe it’s a combination of a bunch of stuff.

A team of Carnegie Mellon researchers led by George Loewenstein decided to make progress on this question with a creative experiment — they took a bunch of heterosexual couples, asked some of them to have more sex, and didn’t give any instructions to the others. Both members of every couple regularly filled out online surveys about their moods, sexual frequency, relationship satisfaction, and a bunch of other measures over the ensuing three months. The have-more-sex group was asked to double its frequency, but didn’t quite get there: Instead, they had sex 40 percent more frequently than the baseline they reported at the start of the experiment.

Did this increase cause members of that group to become happier? The results, published in the Journal of Economic Behavior & Organization, suggest not. In fact, it was the opposite: “The self-reported mood was lower in the increased-sex group than in the control group, and … the effect persisted over all three months of the study.” Couples in the treatment group also became less “coordinated” when it came to how much sex they wanted — basically, just less on the same page. There weren’t any notable gender-based differences — “elevating sexual frequency in our study did not have differential effects on male and female members of the couple,” the authors write.

Game over for the sex-causes-happiness theory, right? Well, not so fast. Despite these findings, Loewenstein and his colleagues aren’t giving up on the idea that it might be smart for some couples to have more sex, or that there is a causal relationship between sexual frequency and happiness in general:

Rather, the evidence presented here seems to be most consistent with the idea that the directive, in the treatment condition, to have more sex affected the couples’ intrinsic motivation to have sex. Perhaps being in the experimental treatment changed couple members’ construal of sex, from a voluntary activity engaged in for pleasure to a duty, engaged in at the behest of the experimenter. Consistent with the latter account, numerous studies (e.g., Pepe and Byrne, 1991) have found declines in sexual satisfaction among couples engaged in infertility treatment. With the focus on timing sex to match the ovulation cycle, infertility treatment may transform sex from an activity driven by desire to an instrumental activity driven by the desire to procreate. 

In other words, the researchers think their experiment may have turned sex from an activity couples did because they wanted to into an obligation, a chore. It’s easy to see how this could be a problem for any couple trying to have more sex. As soon as it’s stated explicitly as a goal, there’s a chance it becomes “a thing” of its own, another responsibility to toss atop all the others, whereas “regular” sex is supposed to happen spontaneously.

I emailed Loewenstein to ask if he had any thoughts on how couples can get around this. He did have one suggestion: “Instead of having the usual veto rule, whereby the couple doesn’t have sex if either member doesn’t want to have it,” he said, “the couple should switch to an all-it-takes-is-one rule, where you have sex if at least one member wants to.” Would this work, or would it just introduce another version of this problem in which the less libidinous partner feels like they’re having sex out of obligation? Someone should run an experiment to find out.