New research suggests that more sex does not lead to increased happiness.

Carnegie Mellon University found that that simply having more sex did not make couples happier, in part because the increased frequency led to a decline in wanting for and enjoyment of sex. This positive relationship between sex and happiness may be observed because being happy in the first place, for example, might lead someone to have more sex, or being healthy might result in being both happier and having more sex.

In the study, researchers examined the causal connection between sexual frequency and happiness, Carnegie Mellon University researchers experimentally assigned some couples to have more sex than others, and observed both group's happiness over a three month period. In a paper published in the Journal of Economic Behavior & Organization, they report.

One hundred and twenty eight healthy individuals between the ages of 35 and 65 who were in married male-female couples participated in the research. The researchers randomly assigned the couples to one of two groups. The first group received no instructions on sexual frequency. The second group was asked to double their weekly sexual intercourse frequency.

They found that the couples instructed to increase sexual frequency did have more sex. However, it did not lead to increased, but instead to a small decrease, in happiness. Furthermore, the researchers found that couples instructed to have more sex reported lower sexual desire and a decrease in sexual enjoyment. It wasn't that actually having more sex led to decreased wanting and liking for sex. Instead, it seemed to be just the fact that they were asked to do it, rather than initiating on their own.

"Perhaps couples changed the story they told themselves about why they were having sex, from an activity voluntarily engaged in to one that was part of a research study. If we ran the study again, and could afford to do it, we would try to encourage subjects into initiating more sex in ways that put them in a sexy frame of mind, perhaps with baby-sitting, hotel rooms or Egyptian sheets, rather than directing them to do so," George Loewenstein, the study's lead investigator, said in a statement.

However, Loewenstein said he believes that most couples have too little sex for their own good, and thinks that increasing sexual frequency in the right ways can be beneficial.

The findings are detailed in the Journal of Economic Behavior & Organization.