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All of the hormones released during sex are pretty much perfect for improving a person's mood. They make people feel relaxed, can encourage compassion, and even act a pain relievers. A 2007 study on women also found that physical affection or sexual behavior (with a partner) one day predicted less stress and a more positive mood the next. As you might expect, the stress-sex cycle held true: positive mood one day was also a predictor of more physical affection or sexual activity with a partner the day after. "The better you feel, the happier you are, the more sex you have and the more you want to have sex," says Downs. Unfortunately, he says simply jumping into bed when stressed isn't likely to fix the problem.