What is the sexual response cycle?
The sexual response cycle refers to the sequence of physical and emotional changes that occur as a person becomes sexually aroused and participates in sexually stimulating activities, including intercourse and masturbation. Knowing how your body responds during each phase of the cycle can enhance your relationship and help you pinpoint the cause of sexual dysfunction. It is not the only model of a sexual response cycle, but it is the best known one.
What are the phases of the sexual response cycle?
The sexual response cycle has four phases: desire (libido), arousal (excitement), orgasm and resolution. Both men and women experience these phases, although the timing usually is different. For example, it is unlikely that both partners will reach orgasm at the same time. In addition, the intensity of the response and the time spent in each phase varies from person to person. Many women will not go through the sexual phases in this order. Some of these stages may be absent during some sexual encounters, or out of sequence in others. A desire for intimacy may be a motivation for sexual activity in some individuals. Understanding these differences may help partners better understand one another’s bodies and responses, and enhance the sexual experience.
Several physiologic changes may occur during different stages of sexual activity. Individuals may experience some, all, or none of these changes.
Phase 1: Desire
General characteristics of this phase, which can last from a few minutes to several hours, include the following:
- Muscle tension increases.
- Heart rate quickens and breathing is accelerated.
- Skin may become flushed (blotches of redness appear on the chest and back).
- Nipples become hardened or erect.
- Blood flow to the genitals increases, resulting in swelling of the woman’s clitoris and labia minora (inner lips), and erection of the man’s penis.
- Vaginal lubrication begins.
- The woman’s breasts become fuller and the vaginal walls begin to swell.
- The man’s testicles swell, his scrotum tightens, and he begins secreting a lubricating liquid.
Phase 2: Arousal
General characteristics of this phase, which extends to the brink of orgasm, include the following:
- The changes begun in phase 1 are intensified.
- The vagina continues to swell from increased blood flow, and the vaginal walls turn a dark purple.
- The woman’s clitoris becomes highly sensitive (may even be painful to touch) and retracts under the clitoral hood to avoid direct stimulation from the penis.
- The man’s testicles are withdrawn up into the scrotum.
- Breathing, heart rate and blood pressure continue to increase.
- Muscle spasms may begin in the feet, face and hands.
- Tension in the muscles increases.
Phase 3: Orgasm
This phase is the climax of the sexual response cycle. It is the shortest of the phases and generally lasts only a few seconds. General characteristics of this phase include the following:
- Involuntary muscle contractions begin.
- Blood pressure, heart rate and breathing are at their highest rates, with a rapid intake of oxygen.
- Muscles in the feet spasm.
- There is a sudden, forceful release of sexual tension.
- In women, the muscles of the vagina contract. The uterus also undergoes rhythmic contractions.
- In men, rhythmic contractions of the muscles at the base of the penis result in the ejaculation of semen.
- A rash or "sex flush" may appear over the entire body.
Phase 4: Resolution
During this phase, the body slowly returns to its normal level of functioning, and swelled and erect body parts return to their previous size and color. This phase is marked by a general sense of well-being and, often, fatigue. Some women are capable of a rapid return to the orgasm phase with further sexual stimulation and may experience multiple orgasms. Men need recovery time after orgasm, called a refractory period, during which they cannot reach orgasm again. The duration of the refractory period varies among men and changes with age.