IN YOUR 40s

The Advantages:

Call of the cougar: As a new study conducted at the University of Texas at Austin posits, female sex drive may actually increase as a woman's sex hormones and fertility decrease. "Women with declining fertility think more about sex, have more frequent and intense sexual fantasies, are more willing to engage in sexual intercourse, and report actually engaging in sexual intercourse more frequently than women of other age groups," say the study authors. It seemed surprising to many when the findings were announced, but the researchers have an explanation: They theorize that our female ancestors were so accustomed to losing children to disease, war, or starvation that they evolved to crave more sex--at a relatively advanced age--to produce more babies.

The Challenges

The perils of perimenopause: "By 40," says Glenn D. Braunstein, MD, an endocrinologist and chair of the department of medicine at Cedars-Sinai Medical Center in Los Angeles, "a woman's testosterone levels will be about half the level they were at twenty-five." And yes, that drop certainly affects libido. For the average woman who enters perimenopause (defined as the 4 or so years leading up to her final period) in her late 40s, fluctuating estrogen, progesterone, and testosterone levels may put a damper on bedroom bliss. Irregular periods and even her first hot flashes may appear.

Essential Health Information

To smooth things out, Steven R. Goldstein, MD, a professor of obstetrics and gynecology at NYU Langone Medical Center and immediate past president of the North American Menopause Society, prescribes low-dose birth control pills for many of his patients "to turn off the ovaries' erratic estrogen production and replace it with a small, consistent influx of estrogen every day." If dryness and discomfort develop, local estrogens--placed directly into the vagina in the form of a suppository, cream, or "ring"--can improve lubrication and pleasure for many women. (Estrogens that are applied locally to the vagina are widely believed to be safer than oral estrogens, which carry some cancer risks.)

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IN YOUR 50s

The Advantages:

With maturity, expertise: As author Gail Sheehy wrote in her classic book on aging, Sex and the Seasoned Woman: "The middle years, between 50 and 65, constitute the apex of adult life...For women, the passage to be made is from pleasing to mastery." Indeed, the National Survey of Sexual Health and Behavior found that 71% of 50-somethings surveyed--more than any other age group--said their last sexual experience resulted in an orgasm.

The Challenges:

Manipulating menopause: Because of dramatically reduced testosterone and virtually nonexistent estrogen, sex drive drops after menopause. But the options are plentiful if you want to rev things up:

Testosterone therapy using creams, gels, or patches has not been approved by the FDA and can only be prescribed off-label, but a growing number of women vexed by low sex drive swear by it. Physicians often prescribe very small off-label doses of testosterone along with menopausal hormonal therapy, or MHT. Many women try MHT (formerly called hormone replacement therapy, or HRT), which involves taking estrogen and progestin to relieve vaginal dryness and hot flashes and reduce bone loss. MHT is controversial, not only because studies show it can increase women's risk of strokes, heart attacks, and breast cancer, but also because some forms can sap testosterone, causing libido to wane even more.

Pesky pounds: The more body fat you have, the less libido-boosting "free-floating" testosterone you have. If you're obese, losing 10% of your total weight can do wonders for your sex drive, found researchers at Duke University Medical Center. Multiple studies have also shown that after just 20 minutes of exercise, blood flow to the genitals increases, resulting in more lubrication, better arousal, and better orgasms.

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