Those who had unprotected sex were in a better mood because....well

So, study of the week: Dr. Lazar Greenfield, the (recent) president-elect of the American College of Surgeons referred to the research from the Archives of Sexual Behavior " which found that female college students practicing unprotected sex were less likely to suffer from depression...."
The three psychologists who wrote the peer-reviewed article cited by Greenfield are Rebecca L. Burch, Gordon G.Gallup Jr., and Steven M. Platek.
Platek told Michael Smerconish, the columnist who wrote the article for the Phil Inq, that human semen has the potential to produce profound effects on women."
And he said that "only 5 percent of the ejaculate is sperm...whats left is a rich concoction of chemicals, including many that have the potential to produce mood-altering effects derived from hormones, neurotransmitters, and endorphins. There are even female hormones in male semen. Within an hour or two after insemination, you can detect heightened levels of many of these seminal chemicals in a woman's bloodstream..."