If you're thinking that the benefits of a hefty bank account could help turn up the heat in the bedroom, you're at least partly right.Money might not buy love, but it can allow for a sizzling sex life.About 70% of multimillionaires -- with a mean net worth of a whopping $90 million -- say they enjoy better and more adventurous sex, according to a 2007 survey by Prince & Associates Inc., a marketing research firm specializing in global private wealth."Fully 63% of rich men said wealth gave them 'better sex,' which they defined as having more-frequent sex with more partners. That compares to 88% of women who said more money gave them better sex, which they defined as 'higher quality' sex," writes Robert Frank in an article for the Wealth Report entitled "The Rich Libido."It makes sense when you think about it: Money relieves much of the life stresses that most of us have to deal with, helping those 1%ers relax and let go.The security of extreme wealth can provide a sense of stability that many people, particularly female millionaires, find empowering. And expensive toys like private jets and trips to exotic locales certainly don't hurt, either.Hooking up with the rich may even improve the quality of sex, at least for women. In a 2009 study (PDF), researchers at Newcastle University found that as male partners' income increased, so did the frequency of women's orgasms.Could money act as an aphrodisiac? Maybe. Or, as the study's authors suggest, perhaps wealth-inspired orgasms are the result of evolution, helping women discriminate between men to find those that have the best provider potential.However, a partner who can provide more resources and more orgasms may not necessarily be the best long-term bet, because wealth changes people, and not always for the better.According to social psychologist Justin Lehmiller, "Wealthier people engage in more dishonest and unethical behavior, and these traits may follow them into the bedroom. In fact, research has found that power and wealth are linked to a higher likelihood of infidelity."But luckily for all of 99%ers, sex itself may confer more happiness than money ever could.In one study, researchers at Dartmouth College and the University of Warwick, England, measured levels of happiness in 16,000 men and women. They found that the more sex people had, the happier they were, regardless of their age or whether they were male or female.And while money was found to buy more sexual partners, it didn't necessarily buy more sex. In fact, men who paid for sex were considerably less happy than those who didn't, which makes sense.According to Lehmiller, "You can buy all of the sex you want, but at the end of the day, most of us want and need more than a few moments of physical contact. Purchasing sex does not meet our psychological needs for intimacy and emotional connection."The researchers even found that sex is so closely tied to happiness that they estimated increasing sexual intercourse from once a month to once a week would have the same mood-boosting effects as adding $50,000 a year in income.Sex may contribute to your happiness -- and your actual bank account -- in other ways, too. According to research by biological anthropologist Dr. Helen Fisher, people who have more sex might do better at work.Sex triggers the release of various brain chemicals, such as dopamine, vasopressin and oxytocin, which are associated with creativity, problem-solving, cooperation and confidence. It stands to reason, says Fisher, that regular sex might improve performance in the boardroom as well as the bedroom.So how can you reap these rewards? Invest in your relationship by giving it the same time and attention that you would your retirement portfolio. Make time for date nights. Make sure that the number of positive interactions with your partner outnumbers the negatives.Practice 30-second hugs to get those feel-good chemicals flowing. Share a cuddle -- and maybe a fantasy or two. Remember, you may not own six homes and a private jet, but when you bank on your relationship, you can feel just as rich.So what makes you happier: sex or money?