More sex leads to a happier marriage, right? Maybe not.

Because quantity doesn’t always equal quality…

Sex is pretty great, right? So great that people think they want to have it as often as possible, seeking out advice on how to have better sex, twice-daily sex, or sex every day for a year.

But what we think we want and what we really want can be very different.

A surprising recent study reveals that when it comes to sex, more isn’t always better. In fact, when married couples doubled the amount of sex they were having, they reported feeling unhappier.

“They were less happy with the sex and they were less happy overall. They wanted [sex] less and liked it less. That seemed to explain most of the change in their overall mood,” says George Loewenstein, Herbert A. Simon Professor of Economics and Psychology at Carnegie Mellon University, and an author of the study.

These findings are contrary to what's known about sex. Most research indicates that people who have more sex report being happier. But the relationship has never been clear. Did having more sex make people feel happier? Or did happier people have more sex?

Loewenstein hoped to understand the relationship between joy and sex. He recruited 64 straight heterosexual married couples between the ages of 35 to 65, specifically focusing on couples who had regular sex at least once a month and no more than three times a week. (Loewenstein did not include couples who already had sex four to seven times a week simply because he thought it would be tough for them to double their amount.)

Over a three-month period, half of the couples did not change their sex habits, and while the other half doubled the amount of sex they had.

Both before and after the study, each person in the couple independently answered questions about personality traits, mood, demographics, libido, relationship quality, and interest in sex. Then, every morning during the study, participants completed a 10-minute survey about their mood, personality, and frequency of sex.

People in the group having more sex reported feeling less happy overall, less happy with their sex lives, and less desirous of sex. And, the couples felt out of synch.

"Being in the have-more-sex condition seemed to disrupt the natural harmony of the couples," says Loewenstein.

He admitted that he felt he was shocked by the findings. He believes the conventional wisdom that if people enjoy sex, they'd enjoy having it more often.

"The sex drive reinforces itself," he says. The more people have it, the more they want it. But the findings did not show this at all.

Erick Janssen —a senior researcher fellow at the Kinsey Institute for Research in Sex, Gender and Reproduction, who was not involved with the study, believes it makes sense that an increase in sexual frequency might not lead to happiness.

"We are all different. So more sex may be good for some, and not for others—especially if one or both … might prefer to have less frequent sex," he writes via email.

Too much of a good thing is ... too much?

Loewenstein thinks the experimental conditions could be the reason why the couples knocking boots more often didn't feel happier. Couples already might be having the perfect amount of sex. Doubling that amount, which might sound fun, could actually be too much.

"They decide to have exactly as much sex as is good for them. If they have more, it is worse," he Loewenstein says.

In other words, while the participants might have believed they wanted to have more sex, perhaps doubling the frequency felt like a chore.

Despite the findings, Loewenstein still believes that people should be having more sex.

"I remain convinced that couples don't have enough sex and more sex is good for couples and individuals. Unfortunately, this study did not give me the fodder to make that claim."

How much sex do you have? And is it enough?

Liked this? Try these:

The one person we are thinking about while having sex…

"Have lots of sex." And other advice for my teenage daughter.