Then she heard a radio ad about a new drug trial for women with low libido and joined up in early 2003.

FORBES: Quest for Desire

And while we're lacking such strong statistics for men, I and many other experts believe that low libido is increasingly becoming a problem for guys, too.

CNN: Are you too tired for sex?

Dr. Leah Millheiser, director of the Female Sexual Medicine Program at the Stanford University School of Medicine, has been conducting studies looking at the MRI images of women with extremely low libido.

CNN: When a woman doesn't want sex