Their paper, "Money, Sex, and Happiness: An Empirical Study," recently published by the National Bureau of Economic Research, essentially puts an estimated dollar amount on the happiness level resulting from sex and its trappings.

Despite popular opinion, they find that having more money doesn't mean you get more sex; there's no difference between the frequency of sex and income level. But they do find sex seems to have a greater effect on happiness levels in highly educated—and presumingly wealthier—people than on those with lower educational status.

Overall, the happiest folks are those getting the most sex—married people, who report 30 percent more between-the-sheets action than single folks. In fact, the economists calculate that a lasting marriage equates to happiness generated by getting an extra $100,000 each year. Divorce, meanwhile, translates to a happiness depletion of $66,000 annually.

Whether that hefty happiness income boost is the result of marital bliss or more sex is up for debate. But their "econometric" calculations confirm what psychologists have long known: People who consider themselves happy are usually richer in sexual activity.

"Many studies confirm that people who are depressed have less sex," says psychologist and sex therapist Robert Hatfield, PhD, of the University of Cincinnati and a spokesman for the Society for the Scientific Study of Sexuality. "Conversely, if you're not depressed—'happy,' as some might say—you're more likely to have more frequent sex."

Does sex lead to happiness, or are happy people just more likely to lead each other to the bedroom? That's still under investigation, but there is evidence that psyche and sex feed off each other.

Reviewed by Brunilda Nazario, MD on July 16, 2004