Dear Dr. Myrtle,
I’d like to get some confirmation on my experience that my interest in sex goes in waves that roughly correlate with my menstrual cycle. Am I really changing estrogen quantities sufficiently to go from nymphomaniac to happy celibate?
Sexual desire, also know as "libido", is probably one of the most under-discussed and most-wondered-about emotions. There is lots of available information about sex and reproduction, sex and illness, or sex and advertising, but not a whole lot about personal sexual desire.
A review of physiology: If you think about a woman’s menstrual cycle as beginning the first day she bleeds, that day would be day one, and you could continue counting each day until the next day she bleeds. The average number of days between bleeding (a "cycle") for most women is about 28 days, although there is often variation.
The cycle can be further thought of as being divided into two halves: the first half being a hormonal preparation for ovulation (the "follicular phase"), and the second half (the "luteal phase") a preparation for menstruation. Levels of the hormone estrogen begin to rise before the first day of bleeding, and continue at a high level until ovulation. Levels of the hormone progesterone rise after ovulation and continue until a few days before bleeding. There’s more to it, but those are the basics.
Back to the question. Research shows that women, on average, report more sexual desire (libido), more sexual activity, and more interest in erotica during the pre-bleeding, bleeding, and first phase (follicular phase) of their cycles. This would seem to support a "hormone = libido" theory. For more information on this topic, read the book The Alchemy of Love and Lust, by T. Crenshaw. This book is an absorbing treatise on how sex hormones might influence our relationships.
But ...! Several studies have shown that sexual desire does not correlate with estrogen or progesterone levels. Some studies have shown a change in libido which was related to testosterone levels, however, which fluctuate in both women and men. Confusing the issue more, when women reporting low sexual desire were compared hormonally to women with "normal libido", the blood hormone levels in the two groups were statistically the same.
Is libido more linked to hormones, or to something else? Sexual desire is influenced by many different things. It’s probably the case that there are some hormonal influences on libido; however what you’re thinking (cognition) is more important to desire than hormones levels alone. There are several observations that support this:
- Learning more about your own arousal can allow you to achieve more arousal, even though your hormone levels stay as they always were. When women who report low libido, participate in "orgasm training" (educational effort and "hands on practice"), they report feeling more sexually aroused and more sexually assertive, even six months after the training. Their hormone levels, however, did not change one bit.
- Sexual desire does not change in approximately 50-70 percent of post-menopausal women. This means that when a woman has stopped cycling her estrogen and progesterone (the "pause" in the "meno"), her sexual desire is most often unaffected. This is supported by the observation that women’s testosterone levels decline, if at all, very slowly before, during and after menopause.
- Other social and medical factors, such as loss or unavailability of a partner, health status, or partner discord have been shown to be far more influential than postmenopausal hormone levels (including testosterone).
Testosterone has gotten lots of press, but when you look at research with willing humans, it is generally women who have other medical conditions (pituitary problems), or have had their ovaries removed who most benefit from testosterone replacement. Even then, it’s a tight-rope balance act, where too much gives you facial acne and irritability ("testy" comes from "test"osterone), and not enough leaves you without a sex drive. Other people with "normal" testosterone levels have not been shown to benefit from pills or injections of testosterone.
(An aside: testosterone creams have some effect on women’s arousal, but we wonder whether a sexual lubricant might not do the same thing. The women reported feeling "sexier" and "wetter", which might have been from rubbing in the lotion that the testosterone was put into. Women also report that 10-20 minutes of massage with a Viagra cream helps too, but taking a Viagra pill is not effective. See a connection? No study has been done that we are aware of that uses sexual lubricant and vulvar massage for 10-20 minutes to see if that helps women’s sexual arousal. We could foresee the line of women waiting to get into that study, though.)
The answer? I suspect that the most important determinant of libido is cognition (what you’re thinking). These studies show that if you don’t have a cognitive sense of desire, that your hormonal level won’t matter much. Hormones are to libido what icing is to cake: hormones may enhance an underlying sexual desire, but aren’t responsible for developing the desire in the first place.