Researcher Reveals When Women Are Most Likely To Want Sex
UC Santa Barbara researcher James Roney, a professor in the Department of Psychological and Brain Sciences, states that he knows when women are most receptive to the idea of having sex. In a recent article published in the journal Hormones and Behavior, Dr. Roney reveals data gleaned from a population of female undergrad students that shows two specific hormones act as sex-on and sex-off switches in the female brain during the menstrual cycle—estrogen and progesterone―and when they are flicked on and off.
According to a press release issued by UC Santa Barbara:
"We found two hormonal signals that had opposite effects on sexual motivation," said Roney, the article's lead author. "Estrogen was having a positive effect, but with a two-day lag. Progesterone was having a persistent negative effect, both for current day, day before, and two days earlier."
Although previous animal studies have thoroughly documented the connection between hormone levels and sexual receptivity in females of several non-human primate species, Dr. Roney says that little has been known and documented regarding specific hormonal signals acting as predictors of sexually motivated behavior in women during their menstrual cycles.
In the study, saliva samples were collected daily from young female college students throughout 1 to 2 menstrual cycles that were subsequently assayed for their levels of the sex hormones estradiol, progesterone, and testosterone. Furthermore, the women were also queried about their daily sexual behavior and their level of desire to have sex on each day throughout the study period.
What the data revealed was that after their estrogen levels peaked (along with their receptiveness to having sex or desire to have sex) during the participants’ first half of their menstrual cycles, rising levels of progesterone that normally occur during the mid-cycle to luteal phase (the second half of the menstrual cycle) led to a drop in sexual behavior and desire.
"Progesterone acting as a potential stop signal within cycles is a novel finding in humans," noted Roney. "We know in rhesus monkeys there is a strong negative correlation with progesterone and a positive correlation with estrogen. The patterns are actually comparable to what you see in non-human primates, but hadn't been shown in humans."
The conclusion reached by Roney and his co-author colleague Zachary L. Simmons is that we can now say that the hormones estrogen and progesterone act as hormonal predictors toward sexual motivation in human females.
However, possibly one of their more-surprising findings is that testosterone appears to play little to no role in mediating sexual behavior in women.
"There's a common belief in the medical literature that testosterone is the main regulator of women's libido," he explained. "Doctors tend to believe that, though the evidence isn't that strong in humans. In the natural cycles, we weren't finding effects of testosterone. It wasn't significantly predicting outcomes."
Dr. Roney points out that their finding regarding testosterone is limited to the naturally occurring endogenous menstrual cycle in women and not to the effects realized when post-menopausal women may be receiving testosterone during exogenous hormone replacement therapy.
"Testosterone has those effects [increased sexual motivation] if you inject it externally in women who are menopausal, and there are a lot of reasons that might be the case," says Dr. Roney. "For example, testosterone can be converted to estrogen through a particular enzyme. If you inject menopausal women with testosterone, it might be acting as a device that's delivering estrogen to the target cells. So the fact that it works doesn't necessarily mean it's an important signal in the natural cycle."
Dr. Roney hopes to extend his research to older, married women to develop a complete model of hormonal predictors in all sexually active women.
"Undergraduates might be unique for a lot of reasons," says Dr. Roney. "Their hormone levels tend to be a bit different from those of women even just a little bit older. And married women in their 30's are likely to be more consistently sexually active, and that might change the patterns in some ways. They also tend to have higher hormone secretion and more regular cycles than younger women."
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Reference: “Hormonal predictors of sexual motivation in natural menstrual cycles” Hormones and Behavior Vol. 63, Issue 4, April 2013, pp. 636-645; J.R. Roney and Z.L. Simmons.