The Four Stages of the Male Sexual Response Cycle and an Overview of Male Sexual Function and Common Dysfunctions

Male sexual response is a systemic reaction process that occurs after sexual stimulation, under the comprehensive regulation of the nervous, endocrine, and psychological systems. It encompasses the entire process from sexual arousal, penile erection, orgasm, the accumulation of sexual tension, to ejaculation, and then back to a state of calm. This process can be divided into four stages: the excitement phase, the plateau phase, the orgasmic phase, and the resolution phase. Within each stage, the body undergoes regular physiological changes. Psychological factors, medications, fatigue, and endocrine disorders can all affect the sexual response cycle.

The duration and intensity of the sexual response cycle vary considerably. The arousal phase can typically last from a few minutes to several hours, the plateau phase from 0.5 to 3.4 minutes, the orgasm phase from only 10 to 15 seconds, and the resolution phase from 10 to 15 minutes. Approximately three-quarters of men ejaculate about two minutes after penile penetration, one-quarter can ejaculate for 10 to 30 minutes, and a very small number can last for more than one hour.

Sexual arousal is caused by physical and psychological sexual stimulation. This stimulation includes visual, auditory, olfactory, and tactile sensations, as well as the erogenous zones and erogenous zones of the opposite sex, all of which can arouse sexual excitement. In men, the sexual arousal response is concentrated in the penis, which becomes engorged and erect, with the tunica albuginea surrounding the corpora cavernosa fully stretched and hardened due to pressure. However, fatigue, anxiety, environmental factors, illness, and psychological factors can cause the penis to become weak or unable to achieve an erection. The scrotum rises, and the skin of the scrotum contracts and thickens. The testes enlarge and rise in position. A small amount of fluid secreted by the bulbourethral glands and prostate gland appears at the urethral opening. The breasts develop, especially the nipples, which harden. The heart rate increases, reaching over 100 beats per minute; blood pressure rises slightly, and breathing becomes slightly faster.

As intercourse progresses, penile erection becomes pronounced, and sexual excitement is heightened but still below the orgasm threshold, preventing immediate ejaculation; this is known as the plateau phase. During this phase, the heart rate increases significantly, reaching 100-170 beats per minute; blood pressure rises, with systolic pressure increasing by 20-80 mmHg and diastolic pressure increasing by 10-40 mmHg; and respiration further accelerates.

The orgasmic phase is the most crucial and briefest stage of the sexual response. Physical tension reaches its peak, the penis achieves a strong erection, and the man experiences pleasure through ejaculation, ending the tension. The orgasmic response lasts only a few seconds, during which intense muscle spasms release the pent-up emotions. These spasms bring wave-like pleasure, producing involuntary rhythmic muscle contractions, and the resulting extreme pleasure radiates from the penis throughout the body. During orgasm, the penile urethra begins to contract, with intervals of 0.8 seconds, 3-4 times in total, followed by a gradual decrease in frequency and amplitude until cessation. The rectal and anal sphincter muscles also exhibit involuntary contractions at intervals of approximately 0.8 seconds; the heart rate can reach 110-180 beats per minute; blood pressure rises, with systolic pressure increasing by 40-100 mmHg and diastolic pressure by 20-50 mmHg; breathing accelerates, exceeding 40 breaths per minute; and sweating occurs in the palms and soles. Psychologically, the individual achieves orgasm and sexual satisfaction.

The resolution phase is the period after orgasm until the body and emotions return to calm. During this time, muscles relax, the penis begins to soften (this softening can be rapid or slow), the scrotal skin relaxes, and the size and position of the testicles return to normal. Psychologically, there is satisfaction, and emotions tend towards calm.

Sexual function is a human instinct and the foundation for reproduction and procreation. Male sexual function is essential for men to engage in sexual activity; disorders of male sexual function will affect normal sexual activity. For example, erectile dysfunction and premature ejaculation, even with normal internal and external reproductive organs, cannot achieve satisfactory sexual intercourse. Male sexual function includes five stages: libido, penile erection, intercourse, orgasm, and ejaculation. If one or more of these stages, or the entire process, is abnormal and affects normal sexual activity, it is considered sexual dysfunction.

Male sexual function is a complex physiological process involving various aspects, such as nerves, blood vessels, psychological factors, endocrine function, and sexual organs. Among these, the sexual conditioned reflexes of the cerebral cortex play a particularly important and dominant role. Therefore, the causes of male sexual dysfunction are multifaceted and can be broadly divided into two categories: functional sexual dysfunction and organic sexual dysfunction. The former accounts for the vast majority of sexual dysfunctions, while the latter is quite rare.

Common male sexual dysfunctions include: hypersexuality, hyposexuality or lack of libido, erectile dysfunction, priapism, ejaculatory disorders (including premature ejaculation, delayed ejaculation, anejaculation, retrograde ejaculation, dysejaculation, etc.), orgasmic disorders, male sexual aversion, and lack of libido. The most common male sexual dysfunctions are erectile dysfunction and ejaculatory disorders.

Many medications can affect male sexual function, especially when long-term use is required for other medical conditions. If you feel your sexual function is not as good as before, you should consult a specialist to see if you can stop or change your medication to rule out its effects. Some common medications that may affect sexual function are listed below:

(1) Antihypertensive drugs: Almost all antihypertensive drugs have some effect on sexual function. Among them, the most influential are central sympathetic nerve blockers, such as methyldopa, reserpine, guanethidine, clonidine, etc.

(2) Anti-androgen active drugs: such as cimetidine for treating peptic ulcers; spironolactone for diuresis; clofibrate for lowering lipids; finasteride for treating benign prostatic hyperplasia and estrogens.

(3) Neuropsychiatric drugs: such as diazepam, chlorpromazine, nitrazepam, lithium carbonate, phenytoin sodium, imipramine, etc.

(4) Other drugs: such as atropine, propantheline, chlorpheniramine and diphenhydramine.