Source: Abnormal Psychology Textbook (University of Florida)
Difficulty: Intermediate | Prerequisites: Basic understanding of DSM-5 diagnostic framework (Ch. 1–3 notes recommended).
Tags: sexual response cycle, Masters and Johnson, sexual dysfunctions, DSM-5, desire disorders, arousal disorders, erectile disorder, hypoactive sexual desire, female sexual interest arousal disorder, vasocongestion, myotonia, orgasm, refractory period
This chapter sits at the intersection of clinical psychology, biology, and cultural context. It covers three broad areas: sexual dysfunctions, paraphilic disorders, and gender dysphoria. This first set of notes focuses on the normal sexual response cycle and the disorders that disrupt it. Understanding the healthy baseline (Masters and Johnson's model) is essential before you can make sense of where and how things go wrong clinically. You should already be comfortable with how the DSM-5 structures diagnoses, including the role of distress and impairment criteria.
The human sexual response cycle has five phases: desire, arousal, plateau, orgasm, and resolution. Sexual dysfunctions are persistent disruptions at any of these stages that cause significant distress or interpersonal difficulty. The DSM-5 recognises several specific disorders of desire, arousal, orgasm, and pain, each with a minimum six-month duration requirement and exclusion criteria for other causes.
Sexual response cycle
The sequence of physical and emotional changes during sexual activity, described by Masters and Johnson as five phases: desire, arousal (excitement), plateau, orgasm, and resolution. Think of it as the body's roadmap from initial interest through to post-orgasm relaxation.
Vasocongestion (engorgement)
The process by which blood vessels and tissues fill with blood during sexual arousal. In men this produces an erection; in women it causes the clitoris to enlarge, the labia to swell, and vaginal lubrication to begin. In simple terms, it is the blood-flow component of physical arousal.
Myotonia
Muscular tension that builds during sexual activity and culminates in the involuntary muscular contractions of orgasm. Think of it as the tension side of arousal, complementing the blood-flow side (vasocongestion).
Refractory period
A recovery window after male ejaculation during which full erection and another orgasm cannot occur regardless of stimulation. It can last minutes or hours. Women do not have a refractory period in the same way, which is why multiple orgasms are physiologically possible for women.
Sexual dysfunctions
A set of disorders in which people have persistent difficulty responding sexually or experiencing sexual pleasure. The key word is persistent: occasional difficulties are normal and do not meet diagnostic criteria.
Male hypoactive sexual desire disorder
A condition characterised by deficient or absent sexual thoughts, fantasies, and desire for sexual activity in men, causing distress or interpersonal difficulties. Can be lifelong (always present) or acquired (developed after a period of normal desire).
Female sexual interest/arousal disorder
A combined DSM-5 diagnosis for women who experience at least three symptoms of reduced sexual interest or arousal for at least six months. The DSM-5 merged desire and arousal into one diagnosis for women because these experiences frequently co-occur and may not separate as cleanly as they do in men.
Erectile disorder (impotence)
Recurrent inability to attain or maintain an erection until the completion of sexual activity, or a marked decrease in erectile rigidity, present on all or almost all occasions over approximately six months. Prevalence increases sharply with age.
Female orgasmic disorder (anorgasmia)
Markedly reduced intensity of orgasms, or persistent delay or absence of orgasm after reaching the excitement phase, in at least 75% of sexual encounters. More common among postmenopausal women.
Premature (early) ejaculation
Persistently ejaculating with minimal stimulation before the man wishes to, specifically within one minute of penetration on 75% or more of occasions over at least six months. Can be lifelong or acquired.
Delayed ejaculation
Marked delay or absence of orgasm following the excitement phase in at least 75% of sexual encounters. There is no universally agreed definition of what counts as "delayed," but a common pattern is inability to ejaculate during intercourse while still able to do so with manual or oral stimulation.
Genito-pelvic pain/penetration disorder
A DSM-5 diagnosis for women who, for approximately six months, recurrently experience pain or muscle tightening during sex, or who have marked fear or anxiety about experiencing such pain. This diagnosis consolidates what were previously separate concepts of dyspareunia and vaginismus.
Vaginismus
Involuntary contraction of the muscles surrounding the outer third of the vagina when penetration (with a penis, finger, tampon, or speculum) is attempted. Some women with vaginismus can still experience arousal and orgasm through clitoral stimulation. For others, even the anticipation of insertion triggers the spasm.
Masters and Johnson's research established the foundational model of what happens physiologically and emotionally during sexual activity.
The cycle consists of five phases:
Desire – the urge to engage in sexual activity.
Arousal (excitement) – psychological pleasure combined with physiological changes: vasocongestion and myotonia.
Plateau – excitement stabilises at a high level. A pleasurable sustained phase.
Orgasm – discharge of neuromuscular tension built up in the preceding phases. In men: rhythmic contractions of the prostate, penis, and urethra with ejaculation. In women: rhythmic vaginal contractions and irregular uterine contractions (not always felt).
Resolution – the entire musculature relaxes into a deep state of rest.
The length and distinctiveness of each phase varies across individuals.
Women's responses tend to be more variable than men's, which means the original Masters and Johnson model may be more representative of typical male patterns.
Women have no refractory period, making multiple orgasms physiologically possible, though not all women find them desirable or easy to achieve.
Sexual dysfunctions are disorders in which a person has persistent difficulty with sexual response or pleasure.
To qualify as a clinical disorder, the difficulty must be more than occasional or transient, and must cause significant distress or interpersonal problems.
DSM-5 diagnostic requirements:
Dysfunction present most of the time for at least six months.
Causes significant distress or impairment.
Not better explained by another psychiatric condition (e.g. depression), substance use, medications, or severe relationship stressors.
If substances or medications are the primary cause, the diagnosis is substance/medication-induced sexual dysfunction instead.
Dysfunctions frequently overlap: many individuals present with more than one.
Clinicians must consider partner factors, relationship quality, individual vulnerability, cultural or religious beliefs, and medical conditions when diagnosing.
Sexual desire can manifest as thoughts, fantasies, interest in initiating or participating in sex, and awareness of sexual cues.
Levels of desire vary between people and fluctuate over time within the same person.
Low desire or arousal is among the most common reasons people seek treatment.
Male hypoactive sexual desire disorder
Little or no desire for sex, deficient or absent sexual fantasies, no initiation of sexual activity.
May be unresponsive when a partner initiates.
Lifelong type: the person reports never having had much interest in sex, with anyone or privately.
Acquired type: the person previously enjoyed sex but lost interest. This is the more common presentation.
Inhibited desire can be generalised (applies to all situations) or specific (limited to certain partners or contexts).
Judgement about what counts as "low" desire is inherently subjective; the clinician considers the full context of the person's life.
Higher prevalence among older men.
Female sexual interest/arousal disorder
The DSM-5 combines desire and arousal difficulties into a single diagnosis for women, reflecting research showing these often co-occur.
Men's desire is typically defined by the presence of sexual fantasies and yearning for sex. Women may seldom have spontaneous fantasies yet still want and enjoy sex, and desire and arousal appear more intimately connected for women.
Diagnosis requires at least three of the following symptoms for at least six months: absent or significantly reduced interest in sexual activity, in erotic thoughts or fantasies, in initiation of or receptiveness to sex, in excitement or pleasure during most sexual encounters, in responsiveness to erotic cues, or in genital/nongenital responses to sexual activity.
Should not be diagnosed simply because of a desire discrepancy between partners.
"Most" in the criteria means absent or significantly reduced in roughly 75–100% of encounters.
Women with low arousal are more likely than men to report co-occurring anxiety, depression, and life stress.
Prevalence figures vary depending on whether "distress" is included as a criterion, since some women with low arousal are not distressed by it.
Erectile disorder
Recurrent inability to attain or maintain an erection, or marked decrease in rigidity, on all or almost all occasions over about six months.
Common experience occasionally, but qualifies as a disorder only when persistent and causing significant distress or relationship problems.
Can be lifelong or acquired.
Lifelong cases tend to be associated with psychological contributors and are more amenable to treatment.
Acquired cases are more often linked to biological causes.
Prevalence increases dramatically with age.
Can be both a cause and a result of relationship difficulties.
Female orgasmic disorder (anorgasmia)
Markedly reduced orgasm intensity, or delay/absence of orgasm after reaching excitement, in at least 75% of encounters.
Can be lifelong or acquired. More common among postmenopausal women.
Some women are not distressed by the symptoms and therefore do not seek or receive a diagnosis.
Premature (early) ejaculation
Ejaculation within one minute of penetration, before the man wishes it, on 75%+ of occasions over at least six months.
Can apply to non-vaginal sexual activities as well.
DSM-5 criteria are more specific than DSM-4 was.
Some men attempt to manage it with desensitising creams, multiple condoms, avoiding partner touch, or frequent masturbation, strategies that can leave the partner feeling excluded.
Delayed ejaculation
Marked delay or absence of orgasm following excitement in at least 75% of encounters.
A common pattern: unable to ejaculate during intercourse but can with manual or oral stimulation.
No universally agreed clinical threshold for what counts as "delayed."
Sexual pain in women
Pain during penetration or thrusting, sometimes also present outside of sexual activity.
Potential causes: vaginal dryness (from antihistamines or other drugs), infections of the clitoris or vulval area, vaginal injury or irritation, tumours of internal reproductive organs, poorly healed childbirth injuries (e.g. episiotomy), endometriosis, radiation therapy.
Sexual pain in men
Less common than in women but does occur: painful erections or pain during thrusting.
Vaginismus and genito-pelvic pain/penetration disorder
Vaginismus involves involuntary contraction of muscles around the outer third of the vagina upon attempted penetration.
Some women with vaginismus can still experience arousal and orgasm through clitoral stimulation; for others, even anticipation of insertion triggers the spasm.
The DSM-5 consolidates pain and muscle-tightening presentations into genito-pelvic pain/penetration disorder: recurrent pain or tightening during sex, or marked fear/anxiety about such pain, for approximately six months.
"Occasional erectile difficulty means a man has erectile disorder." Occasional difficulty is normal. The diagnosis requires the problem to be present on all or almost all occasions over about six months.
"Low desire is always a disorder." Desire varies enormously between individuals and across the lifespan. It only becomes a clinical issue when it is persistent, causes distress, and is not better explained by another condition or life circumstances.
"Female sexual interest/arousal disorder is the same as the old DSM-4 categories." The DSM-5 deliberately merged desire and arousal for women into one diagnosis because these experiences overlap more in women than in men.
"Vaginismus means a woman cannot experience any sexual pleasure." Many women with vaginismus can experience arousal and orgasm through clitoral stimulation; the involuntary muscle contraction specifically affects vaginal penetration.
⚠️ Know all five phases of the sexual response cycle and be able to name what happens physiologically at each stage (vasocongestion and myotonia are key terms for the arousal phase).
⚠️ Be clear on the DSM-5 diagnostic requirements that apply across all sexual dysfunctions: six-month duration, significant distress or impairment, and exclusion of other causes.
⚠️ Understand why the DSM-5 combined desire and arousal into one diagnosis for women but kept them separate for men.
⚠️ Know the difference between lifelong and acquired presentations of each disorder, and which type tends to be associated with psychological vs. biological causes (especially for erectile disorder).
⚠️ The refractory period applies to men, not women. This is a commonly tested distinction.
True or False: The plateau phase comes after orgasm in the sexual response cycle.
Fill in the blank: The two key physiological processes during the arousal phase are ________ and ________.
True or False: A sexual dysfunction can be diagnosed if it has been present for three months.
True or False: The DSM-5 uses the same diagnostic structure for desire disorders in men and women.
Fill in the blank: Genito-pelvic pain/penetration disorder consolidates what were previously known as ________ and ________.
Answers: 1. False (plateau comes before orgasm). 2. Vasocongestion and myotonia. 3. False (minimum six months). 4. False (combined into one diagnosis for women, separate for men). 5. Dyspareunia and vaginismus.
Q: Name the five phases of the human sexual response cycle as described by Masters and Johnson.
A: Desire, arousal (excitement), plateau, orgasm, and resolution.
Q: What are the three core DSM-5 criteria that apply to all sexual dysfunction diagnoses?
A: The dysfunction must be present most of the time for at least six months, must cause significant distress or impairment, and must not be better explained by another psychiatric disorder, substance use, medication, or severe stressors.
Q: Why does the DSM-5 combine desire and arousal into a single diagnosis for women but not for men?
A: Research shows that for women, desire and arousal frequently co-occur and are more intimately connected. Women may not experience spontaneous fantasies (the male-oriented definition of desire) yet still want and enjoy sex. The combined diagnosis better captures the female experience.
Q: What distinguishes lifelong from acquired erectile disorder, and which tends to have which type of cause?
A: Lifelong erectile disorder has been present since the onset of sexual activity and is usually associated with psychological contributors amenable to treatment. Acquired erectile disorder develops after a period of normal functioning and is more often linked to biological causes.
Q: How does the DSM-5 define premature ejaculation more specifically than the DSM-4?
A: The DSM-5 specifies ejaculation within one minute of penetration, before the man wishes it, on 75% or more of occasions, over a period of at least six months. The DSM-4 criteria were less precise.
This material connects directly to the chapters on mood disorders and anxiety disorders, since depression and anxiety are both common causes of and co-occurring conditions with sexual dysfunctions. It also links to psychopharmacology: many medications used to treat psychiatric conditions (SSRIs, antipsychotics, lithium) have sexual side effects that can produce or worsen dysfunction.
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