The Beatles urged us to do “it” in the road, but that might have been a smidge too eager, not to mention unhygienic. New research out of the University of Toronto Mississauga suggests that having sex once a week is the trick for optimal conjugal happiness.

More frequently than once a week is not a bad thing, the scientists point out, but there is not the same return on investment.

"Our research suggests that couples do not need to aim to engage in sex as frequently as possible but instead aim to maintain a connection with their partner," said study lead author Amy Muise, a postdoctoral fellow at the University of Toronto Mississauga.

Published in the journal Social Psychological and Personality Science, the findings are based on three studies involving more than 30,000 people in all. The researchers expected – and ultimately confirmed – that sexual frequency has a curvilinear association with well-being where greater sexual frequency is associated with greater satisfaction, but that this association is no longer significant at higher frequencies. The findings were based on three studies involving more than 30,000 people in all.

To gain insight, Muise and her colleagues first looked at results from a survey conducted in the United States every other year between 1989 and 2012. They focused on responses from more than 25,000 people, aged 18 to 89. Participants answered questions about sexual frequency – from not at all to four or more times a week -- and their own perceptions of happiness.

In a second study, researchers surveyed 335 people online, most of whom were heterosexual. Finally, they analyzed findings from a third study, a 14-year survey of American married heterosexual couples.

Analyzing the data, the researchers concluded there was a point of diminishing sexual return beyond once a week.

Muise noted, "It wasn't bad to engage in sex more frequently than once a week. It just wasn't associated with greater well-being on average."

The scientists saw no differences in the findings based on gender, age or length of relationship. And – happily enough – the study found that lovemaking once a week was the average frequency among couples.

"Perhaps this is the average since it seems to maximize the benefits for well-being," Muise said. "It is likely that weekly sex is enough for the average couple to maintain their intimate connection and to feel like they have an active sex life, and this is why we see this as the leveling-off point."