Researchers at UCSB recently observed a link between peaking estrogen levels during young women’s monthly cycles with increased sexual desire and conversely higher progesterone levels with decreased sexual motivation.

The study focused on undergraduate women around the age of 20, who were asked to spit into a test tube every morning and then take an online survey monitoring the degree of their sexual arousal. The test tubes were then collected and sent to a lab to test for the presence of estrogen, progesterone and testosterone.

James Roney, a psychology and brain sciences professor and lead author on the study, said that estrogen levels typically peak before ovulation and have a positive but delayed effect on sexual desire, whereas higher progesterone levels lead to immediate and decreased sexual motivation in women.

“Estrogen was having a positive effect. There was a little time delay though. Estrogen two days earlier was positively predicting their sexual desire. Progesterone had a negative effect. The higher the progesterone, the lower the sexual desire,” Roney said. “Estrogen has a big peak just before ovulation and then it drops, whereas progesterone seems to be low in the first half of the cycle.”

The results of the study support similar trials performed in rhesus monkeys, where their sexual receptivity was heightened in connection with heightened estrogen levels and decreased with higher progesterone levels.

By monitoring the natural hormonal cycle of women, the researchers hope that a comprehensive understanding of the body’s reactions to chemical variations may lead to innovations in treatments for low sex drive. Current trials and medications typically target hormone replacement and combinations of estrogen and testosterone that do not follow a model of the body’s natural cycle.

According to Roney, many professionals do not have an adequate understanding of the signals and mechanisms that underlie sexual desire.

“People, especially doctors, tend to think that testosterone is the main regulator of libido in men and women,” Roney said. “But we found that testosterone does not predict anything and that it does not predict sexual motivation.”

Roney hopes to broaden his studies to different populations and subjects to create a full model of the effects of hormones on sexual desire.



A version of this article appeared on page 5 of the May 7th, 2013′s print edition of the Nexus.