Researchers have found that sex once a week is the optimum amount for maximizing happiness in couples. The study, which was compiled over the last 40 years, suggests that sex once a week helps to maintain intimacy and that couples having it less than once a week reported being less happy. “Most people strive to be happier, and sex is one aspect of life that is thought to be associated with greater happiness,” says Amy Muise, lead author of the study. While sex once a week can increase happiness, the study also found any more than that won’t make any difference. And, in case you were wondering, there seems to be no consistent association for single people between sexual frequency and happiness.