Have sex just ONCE a week. It was also not designed to identify the causal process, so did not reveal whether having sex up to once a week made couples happier, or being in a happy relationship caused people to have more sex up to once a week. Sex was more strongly associated with happiness than money though. In addition, these findings were specific to people in romantic relationships and in fact, there was no association between sexual frequency and happiness for single people. The key to a successful relationship? The study findings don't necessarily mean couples should engage in more or less sex to reach the weekly average, but partners should discuss whether their sexual needs are being met, the researchers said. The biennial survey, conducted by the University of Chicago, covers a wide range of sociological issues, including opinions about race relations, religion and sex. These participants were additionally asked about their annual income. This included 11, men and 14, women who took the General Social Survey from to A third study analysed survey results collected at three time points over 14 years from more than 2, married couples in the US. Advertisement Share or comment on this article: The researchers also conducted an online survey with people - men, women - who were in long-term relationships and found similar results as the first study. Dr Muise continued it is possible that for single people, the link between sex and happiness is dependent on a number of factors such as the relationship context in which the sex occurs and how comfortable people are with sex outside of relationship. However, sex may be more strongly associated with happiness than is money. For couples, happiness tended to increase with frequent sex, but this was no longer true after couples reported engaging in sex more than once a week. In one study, researchers analysed survey responses about sexual frequency and general happiness from more than 25, Americans.