The Annals of Internal Medicine has published results of a randomized trial that studied the effects of testosterone on women's sexual satisfaction. Testosterone is the sex hormone that is present in both women and men. Men have much higher levels (of course) and there has always been speculation that testosterone and sexual desire/satisfaction are linked.
This study administered testosterone spray in three different doses vs. placebo. They surveyed the women on their sexual "well-being" on a weekly basis by self rating.
Guess what they found? Yes, testosterone did increase these women's libido and "sexually satisfying events". But placebo was just as effective.
Score another one for the placebo effect and the fact that the most important sexual organ may just be the mind.