Sexual arousability and the menstrual cycle

We have repeated a study of the objective (labium minus temperature) and subjective (semantic scales) changes in sexual arousability over the menstrual cycle to erotic video stimulation in 20 women with natural cycles. We extended the study with concomitant vibrotactile stimulation of the clitoral region. In an earlier study women tested for the first time in their follicular phase were sexually more aroused (as indicated by greater increase in labium minus temperature) than women tested for the first time during their luteal phase. When these women were retested in their alternative phase of the menstrual cycle, those who were then follicular did not score higher than those who were then luteal. We then postulated the involvement of a cognitive or conditioned phenomenon which was responsible for the women's repeating their initial phase-dependent response when tested the second time in their alternative phase of the cycle. Identical results were obtained in the present study as far as sexual arousability is concerned during the first test, i.e. follicular women generally scored higher than luteal women; this difference in response persisted during the second test. Concomitant vibrotactile stimulation had no effect on labium minus temperature change but raised subjective sexual arousal and caused a 'more pleasurable' response to the erotic video. Subjective sexual and subjective genital arousal were positively correlated, but neither was significantly correlated with labium minus temperature change. The relationship between menstrual cycle phase and sexual arousal was further substantiated by the reported greater increase in sexual desire after the first erotic video in follicular women than in luteal women. This increased desire, as well as more erotic fantasies, persisted during the next 24 h. In conclusion, studies into effects of menstrual cycle phase on sexual arousability in the laboratory should seriously consider the possible learning and conditioning effects as suggested by the present investigation.