The finding that women who do not use condoms during sex are less     depressed and less likely to attempt suicide than are women who have sex     with condoms and women who are not sexually active, leads one researcher     to conclude that semen contains powerful-and potentially     addictive-mood-altering chemicals.
      Study author Gordon G. Gallup, Ph.D., a psychologist at the State     University of New York in Albany, also found that women who routinely had     intercourse without condoms became increasingly depressed as more time     elapsed since their last sexual encounter. There was no such correlation     for women whose partners regularly used condoms.
      Gallup's survey of 293 college women also found that those who did     not use condoms were most likely to initiate sex and to seek out new     partners as soon as a relationship ended. "These women are more     vulnerable to the rebound effect, which suggests that there is a chemical     dependency," says Gallup.
      Semen contains hormones including testosterone, estrogen,     prolactin, luteinizing hormone and prostaglandins, and some of these are     absorbed through the walls of the vagina and are known to elevate     mood.
      Gallup controlled for variables including method of contraception,     frequency of sexual intercourse, as well as the women's perception of     their relationship. He concedes that women who regularly have sex without     condoms might share personality traits that make them less susceptible to     depression. But the behavior most often associated with non-condom users     is sexual risk-taking, and studies have found no correlation between     high-risk sexual behavior and lower rates of depression.
      Gallup's study, which he deems "the first serious attempt to     investigate the effect of semen chemistry on women," titillated the     public and rankled some academics upon publication in      Archives of Sexual Behavior. Gallup says he has     since replicated the findings with a sample of 700 women and will examine     whether "semen withdrawal" places women at an increased risk for     depression when they are premenstrual, menopausal or have just given     birth, as many women abstain from sex during these periods.