Sexual desire is elusive for many women. A study in the Archives of Internal Medicine dramatically proves this. When 2,207 women ages 30 to 70 who had all been in a steady relationship for the last month were polled, fully 36.2 percent admitted that in the past 30 days they had experienced a tepid sexual desire.

This finding is consistent with previous research, including a 1999 landmark study conducted by University of Chicago sociologist Edward Laumann that found that 32 percent of women reported having a diminished sex drive, compared with only 15 to 17 percent of men. And it's not just U.S. women. The Tribune reports that a study of 1,355 Swedish women between the ages of 18 and 74 found that 33 percent reported low sexual desire "quite often," "nearly all the time" or "all the time."

1. As women enter menopause, their changing hormones cause a falloff in sexual interest.
2. Low sexual desire may be hard-wired into women through evolution. "If women were like men and wanted sex all the time, they'd be pregnant more often" and their bodies would be exceedingly stressed as a consequence of the demands of bearing and rearing children, Chicago's Laumann told the Tribune.
3. Stress. "I consistently find that stress in women doubles or triples the likelihood of reporting a lack of [sexual] interest," Laumann explained to the Tribune.

Men may find this alarming: Fully 75 percent of women who experience a diminished sexual desire say they aren't troubled by it.