Sexual response refers to the physiological, observable, and measurable changes that occur in the body following sexual stimulation. These changes are not limited to the genital area but may also involve other parts of the body. In humans, sexual desire is triggered by sexual stimulation, leading to arousal. As arousal builds to a certain intensity, it culminates in orgasm, releasing accumulated sexual tension. This sequence involves distinct patterns and cyclic changes in behavior, physiology, and psychology, collectively referred to as the sexual response cycle.
The concept of the sexual response cycle was first proposed in 1966 by American researchers Masters and Johnson based on human experimentation. It stands as one of the most significant discoveries in the history of sexual medicine and has since undergone continual refinement. The female sexual response cycle is divided into five phases: the sexual desire phase, sexual arousal phase, sexual plateau phase, orgasm phase, and resolution phase. While it shares many similarities with the male response cycle, it also exhibits unique characteristics.
Sexual Desire Phase
The sexual desire phase refers to the stage where psychological responses are triggered by unconditional and/or conditional sexual stimuli, leading to a desire for sexual activity. It is characterized by sexual fantasies and a psychological yearning for intimacy. This phase involves psychological changes without any significant physiological changes.
Sexual Arousal Phase
The sexual arousal phase begins after sexual desire is activated, marking the onset of sexual tension in the body. During this phase, various physiological and psychological responses occur. In terms of the genital response, this phase is marked by vaginal lubrication, genital engorgement, swelling of the clitoris and labia, and an increase in vaginal length. Vaginal lubrication generally appears 10 to 30 seconds after sexual stimulation and originates from transudate through the vaginal walls, uterine fluids, and secretions from the Bartholin glands. Blood vessel engorgement leads to swelling of the clitoris and labia, and the elongation of the vagina.
Systemic responses include breast swelling and nipple erection, increased heart rate, mild elevation in blood pressure, slightly accelerated breathing, and muscle tension. Compared to men, women tend to have slower arousal and require a longer duration of stimulation and affection to reach the same level of sexual excitement. Psychologically, this phase is experienced as heightened sexual arousal.
Sexual Plateau Phase
The sexual plateau phase refers to the period during which sexual excitement continues to build and sexual tension stabilizes at a high level. This phase is also known as the plateau or peak phase. During this stage, genital engorgement becomes more pronounced, with clitoral erection and increased vaginal lubrication. The outer one-third of the vagina undergoes ring-like constriction, while the inner two-thirds expand and the uterus rises.
Breast swelling intensifies, muscle tension across the body becomes more pronounced, and localized myotonia may occur. Heart rate and respiration accelerate further, and blood pressure rises even higher. A sex flush rapidly spreads to the lower abdomen, shoulders, and occasionally the legs and buttocks. The duration of this phase varies significantly among individuals. Psychologically, there is a heightened state of excitement and anticipation.
Sexual Orgasm Phase
The orgasm phase represents the peak of the sexual response cycle, marked by an intense and brief experience of physiological and psychological pleasure. Building on the plateau phase, this phase is characterized by involuntary rhythmic contractions of the vaginal muscles, anal sphincter, and uterus. These contractions are often accompanied by facial expressions of pleasure, generalized muscle spasms, moaning, sweating, and a brief sense of disorientation.
Heart rate and respiration peak, and blood pressure reaches its highest level during this phase. Sexual orgasm typically lasts from a few seconds to tens of seconds. During this brief period, accumulated sexual tension is quickly released through strong muscular spasms, creating a profound sense of physical and psychological pleasure. Unlike men, women do not experience a refractory period and may achieve multiple orgasms with continuous sexual stimulation.
Sexual Resolution Phase
The resolution phase occurs following orgasm, during which sexual tension gradually dissipates, and the body returns to its pre-arousal state. The first physiological change to occur is the reduction of breast swelling. This is followed by the subsiding of genital engorgement and clitoral swelling. Muscle tone throughout the body returns to normal, and heart rate, blood pressure, and respiration stabilize. Psychologically, individuals often feel a sense of satisfaction and emotional fulfillment after this phase.
The above model is largely based on the male sexual response cycle, but there are distinct aspects specific to women. Unlike men, the sexual desire phase in women may occur after the arousal phase, meaning female sexual desire can be categorized into two types: spontaneous and responsive. Female sexual arousal depends heavily on social and psychological factors in addition to biological influences.
In women, subjective sexual arousal does not always align with physiological responses in the reproductive tract. Some individuals with self-reported arousal disorders may exhibit normal genital engorgement and lubrication during sexual stimulation. Additionally, many women do not engage in sexual activity solely to achieve orgasm. For some, sexual experiences can be pleasurable and fulfilling even in the absence of an orgasm, making the lack of an orgasm an acceptable part of a complete sexual response cycle.