THE SEXUAL RESPONSE CYCLE
Before the 1960s, relatively little was known about the way the body responds during sexual arousal. Scientists were not convinced by Kinsey's claims that some women had more than one orgasm at a time, and it was thought that vaginal lubrication was produced by glands in the cervix and Bartholin's glands. The mechanisms controlling erection and ejaculation in the male were incompletely understood. As a matter of propriety, sexual response was studied in animals, not people. In this climate, the results of an investigation of sexual physiology based on direct laboratory observation of more than 10,000 episodes of sexual activity in 382 women and 312 men.
The findings of this study indicated that human sexual response could be described as a cycle with four stages: excitement, plateau, orgasm, and resolution. These stages correspond to varying levels of sexual arousal and describe the typical responses people have during sexual function. Although it is convenient to use the cycle as a model for descriptive purposes, remember that the stages are arbitrarily defined. They are not always clearly separated from one another and may vary considerably both in one person at different times and between people. Bear in mind also that the physiological processes of sexual response are not simply mechanical movements detached from thoughts or feelings but are part of the sexual involvement and identity of the whole person.
Although the sexual response cycle usually follows a consistent pattern of progression, the simplified schematic patterns of sexual response may vary widely. Sometimes excitation is rapid and leads quickly to orgasm. On other occasions, excitement mounts slowly over a period of hours Ч while having a romantic, intimate meal, for example Ч and the rest of the cycle may seem brief in comparison. The plateau stage may not always lead to orgasm, as the high levels of arousal that characterize this phase may dissipate; and a person may slip back to the excitement phase. If sexual stimulation stops, a person may also drift back into an unaroused state.
There are two basic physiologic reactions during human sexual response. The first is vasocongestion, an increased amount of blood concentrated in body tissues in the genitals and female breasts. The second is increased neuromuscular tension or myotonia. Here, tension does not refer to a negative physical state ("feeling tense") but to a buildup of energy in the nerves and muscles. Myotonia occurs throughout the body in response to sexual arousal, not simply in the genital region. Although there are some differences in male and female sexual response, many details are similar. The physiology of sexual response is also the same for heterosexuals and homosexuals.
Before we discuss the specific details of sexual response, a note of caution is in order. It is often tempting to equate the speed, size, and strength of sexual responses (such as erection, vaginal lubrication, or muscular contractions during orgasm) with the gratification a person experiences or with his/her proficiency as a lover. This is like paying that a bowl of chili is "better" than sirloin steak simply because chili causes a faster and larger secretion of digestive juices than steak. In both cases ("better" digestive response, "better" sexual response), the degree to which one experience is "better" than the other depends on your perspective and on your personal satisfaction.