The next time you consider using the headache excuse to avoid getting busy, think about this: It pays to have more sex. Literally, new research finds.People who have sex four times or more a week earn higher wages than their less-sexually active colleagues at a statistically significant level, according to a discussion paper from Nick Drydakis, a fellow at the Institute for the Study of Labor, a private, independent organization focused on labor market research.To come up with the findings, Drydakis, who is also an economics lecturer in the business school at Cambridge, England-based Angila Ruskin University, analyzed a year-long survey of 7,500 Greek households. The survey asked the representative sample respondents how many times they had sex per week, whether they were employed, how much money they made and how many hours per week they worked, among other questions.But before you rush to go between the sheets, it’s important to note that Drydakis' findings don't indicate that more sex directly translates into a raise. Instead, the study found that the two factors are correlated. See, people who have frequent sex tend to be happier, have higher self-esteem, better reasoning ability and are less likely to be depressed. Other research has found that workers with health problems tend to make less money due to limited productivity and in some cases, discrimination.So to recap: More sex makes you healthier and happier. And happy, healthy people tend make more money.Another factor may explain the positive correlation between more sex and higher wages. People who make more money are often more desirable in the dating market, which means they likely have more sex. Drydakis acknowledges this possibility in his paper, but laments that there isn’t really any literature out there directly addressing this theory.Regardless, the positive relationship between sex and more money exists, his research claims, and workers between the ages of 26 and 50 tend to get higher financial returns on their sexual activity.