It sounds risky, but semen may act as a natural antidepressant. Women who frequently have sex without a condom are less likely to become depressed compared to women who occasionally use protection, women who always use protection and women who abstain from intercourse, according to a study published in the Archives of Sexual Behavior. Ejaculate contains a number of potentially mood-boosting hormones, such as prostaglandins and oxytocin, which women may absorb intravaginally, say researchers.

Do it for your girls: Women who have infrequent or no vaginal intercourse are three times more likely to develop breast cancer than those who have more, according to a French study in the Journal of Clinical Epidemiology. In addition, an earlier American study found that women whose partners used condoms or withdrawal, as well as women not engaging in intercourse at all, had a breast cancer rate five times higher than users of contraceptives that do not reduce vaginal exposure to semen. There are a couple of theories why. Some researchers believe sperm contains antigens that are absorbed through the vagina. Other says oxytocin and DHEA-two "happiness hormones" that increase with arousal-may have a protective effect.

Sex instead of starvation? Yes, please. Women who have the most sex tend to have smaller waists and hips than those who do the horizontal mambo less frequently, according to a German study. Higher levels of body fat are associated with less brain dopamine activity and overeating tends to increase mood-altering levels of serotonin, both of which can impair sexual desire and/or function, says Stuart Brody, PhD, who reviewed the research. At the very least, a vigorous roll in the hay can burn about 50 calories, so go ahead and have that extra chocolate kiss.

Menopause is no excuse to put your libido on lockdown. Nigerian women who had sex at least once every seven days experienced, on average, about 100 fewer hot flashes per week than women who remained abstinent. The improvement may have been due to changes in luteinizing and follicle-stimulating hormones, say researchers.

Sex may make you lose track of time but did you know it can also turn back the clock? In a study conducted at Scotland’s Royal Edinburgh Hospital, researcher David Weeks, PhD, asked a panel of judges to view more than 3,500 participants through a one-way mirror and then guess their age. Turns out the men and women whose ages were regularly underestimated by seven to 12 years were having sex an average of three times a week compared to adults in the same age bracket and their lovemaking lasted three times as long. Sex can help erase stress and sleepless nights, say researchers, both of which can take a toll on your appearance. The only other factor with a stronger correlation to youthfulness was how physically active the study participants were.