Clinical and empirical studies, mainly of North American and European adult women without sexual complaints, have clarified sexual response cycles that are different from the linear progression of discrete phases already mentioned. Women describe overlapping phases of sexual response in a variable sequence that blends the responses of mind and body ().11,12,13,14
That women have many reasons for initiating or agreeing to sex with their partners is an important finding.15
Women's sexual motivation is far more complex than simply the presence or absence of sexual desire (defined as thinking or fantasizing about sex and yearning for sex between actual sexual encounters).
Fig. 1: Sex response cycle, showing responsive desire experienced during the sexual experience as well as variable initial (spontaneous) desire. At the “initial” stage (left) there is sexual neutrality, but with positive motivation. A (more ...)
Recent baseline data from a longitudinal study15
of 3300 multi-ethnic, premenopausal North American women aged 42–52 who had not recently received medication affecting reproductive hormones and who had engaged in sexual activity with a partner during the past 6 months clarified their reasons both to engage sexually (to express love, for pleasure, because the partner wanted to, to relieve tension) and to refrain (lack of interest, tiredness or physical problems [their own or their partner's], or no current partner).15
These findings and those from other studies are in keeping with the sexual response cycle illustrated in .
At the beginning of a given sexual experience, a woman may well sense no sexual desire per se. Her motivations to be sexual are complex and include increasing emotional closeness with her partner (emotional intimacy) and often increasing her own well-being and self-image (sense of feeling attractive, feminine, appreciated, loved and/or desired, or to reduce her feelings of anxiety or guilt about sexual infrequency).15,16,17,18,19,20,21
When a woman is willing to become aroused and enjoy a sexual experience, she focuses on the sexual stimulation she and her partner supply. If the stimulation is as she wishes, sufficient time is available and she can stay focused, her sexual excitement and pleasure intensify. Clearly, the type of stimulation, the time needed and the context (both erotic and interpersonal) are all highly individual. Emotionally and physically positive outcomes will increase subsequent motivation.
Some women report desire that appears to be spontaneous (also shown in ), leading to arousal or to more enthusiasm to find or be receptive to sexual stimuli. This type of desire has a broad spectrum across women and may be related to the menstrual cycle.22
It decreases with age,23
and at any age commonly increases with a new relationship.12,21
Previous definitions of women's sexual dysfunctions unfortunately assumed that the cycle of a woman's sexual response always began with sexual desire, sexual thoughts and fantasies, and that their absence was evidence of a disorder. In a 1992 survey of American adults,4
the most common sexual dysfunction among women 18–59 years of age was low desire, reported by just under a third of those surveyed, with little variation by age. Such results have remained consistent across studies.3,24,25
It is unclear how many of these women are simply reporting low or absent spontaneous desire but do experience triggered desire during sex. Moreover, women report that sexual fantasies can be deliberate — a means to stay focused on the sexual stimulus, rather than an indication of sexual desire.26
Another important finding is that the robust correlation seen in men between subjective arousal and genital congestion (erection) is not seen in women.27,28,29,30
Rather, sexual arousal in women is more strongly modulated by thoughts and emotions triggered by the state of sexual excitement.31
In women, photoplethysmography can be used to measure vaginal vasocongestion and hence to gauge physiological arousal. Female study participants subjected to erotic (usually visual) stimuli can meanwhile report their subjective responses (sexual arousal and positive and negative emotions) by using a Likert scale or a lever that can be moved from left (low arousal) to right (high arousal). In psychophysiological response studies,32,33
women with arousal disorders (as per DSM–IV-TR definitions), despite a lack of subjective arousal and perception of “lack of lubrication/ swelling response” while watching erotic videos, showed increases in vasocongestion comparable to those in control participants without such disorders. Only the women in the control group reported subjective arousal while watching the videos.32
Previous definitions of arousal disorder focused only on genital lubrication and/or swelling response — ignoring 25 years of research showing the poor correlation of genital engorgement with the woman's subjective arousal and excitement in response to sexual stimulation.