The hormone of desire, testosterone, acts on the brain to stimulate sexual interest, sensitivity to sexual stimulation, and orgasmic ability in both sexes. The amount of testosterone circulating in a woman's blood declines by about 50 percent between her twenties and fifties. The most common complaint associated with this decline is a seemingly unexplainable decrease or loss of sexual desire and enjoyment. In I'm Not in the Mood, Dr. Reichman...