Orgasm



Orgasm (from Greek οργασμός orgasmos, from organ to mature, swell, also sexual climax) is the peak of the plateau phase of the sexual response cycle, characterized by an intense sensation of pleasure. Experienced by males and females, orgasm is controlled by the involuntary, or autonomic, limbic system, and is accompanied by quick cycles of muscle contraction in the lower pelvic muscles, which surround the primary sexual organs and the anus. Orgasms are often associated with other involuntary actions, including muscular spasms in multiple areas of the body, a general euphoric sensation and, frequently, body movements and vocalizations are expressed. In males, orgasm usually accompanies ejaculation.

Orgasm is an autonomic physiologic response to sexual stimulation. Brain wave patterns have shown distinct changes during orgasm, which indicate the importance of the limbic system in the orgasmic response. In humans, orgasms usually result from the stimulation of the penis in males and the clitoris in females. Stimulation can be by self-practice (masturbation) or by a partner (penetrative sexual intercourse, non-penetrative sex, and other erotic sexual activities). In addition, partners simultaneously stimulating each other's sex organs by mutual masturbation, penetrative intercourse, or other rhythmic inter-genital contact may experience simultaneous orgasms.

The period after orgasm (known as a refractory period) is often a relaxing experience, attributed to the release of the neurohormones oxytocin and prolactin. Male and female brains demonstrate similar changes during orgasm (by partner controlled orgasm), with brain activity scans showing a temporary decrease in the metabolic activity of large parts of the cerebral cortex with normal or increased metabolic activity in the limbic areas of the brain.

Definitions
Orgasm is usually defined in a clinical context, strictly by the muscular contractions involved during sexual activity, along with the characteristic patterns of change in heart rate, blood pressure, and often respiration rate and depth. Though usually defined as the peak of the plateau phase of the sexual response cycle, characterized by an intense sensation of pleasure, definitions of 'orgasm' vary, and there is sentiment that consensus on how to consistently classify it is absent. At least twenty-six definitions of orgasm were listed in the journal Clinical Psychology Review.

There is some debate whether certain types of sexual sensation should be accurately classified as 'orgasm', including female orgasms caused by G-Spot stimulation alone, and the demonstration of extended or continuous orgasms lasting several minutes or even an hour. The question centers around the clinical definition of orgasm, but this way of viewing orgasm is merely physiological, while there are also psychological, endocrinological, and neurological definitions of 'orgasm'. In these and similar cases, the sensations experienced are subjective and do not necessarily involve the involuntary contractions characteristic of orgasm. However, the sensations in both sexes are extremely pleasurable and are often felt throughout the body, causing a mental state that is often described as transcendental, and with vasocongestion and associated pleasure comparable to that of a full contractionary orgasm. For example, modern findings support distinction between ejaculation and male orgasm. For this reason, there are views on both sides as to whether these can be accurately defined as orgasms.

General
In men, the most common way of achieving orgasm is by the stimulation of the penis; in women, it is the stimulation of the clitoris. Such stimulation can be achieved from a variety of activities. In men, sufficient stimulation can be achieved during vaginal or anal sexual intercourse, oral sex (fellatio), or by masturbation. This is usually accompanied by ejaculation. It is possible for a man to have an orgasm without ejaculation (known as a "dry orgasm") or to ejaculate without reaching orgasm (which may be a nocturnal emission, a case of delayed ejaculation, or a case of anorgasmic ejaculation). In women, orgasm may be achieved during vaginal sexual intercourse, oral sex (cunnilingus), masturbation, or non-penetrative sex in general, and may be by the use of a sensual vibrator or an erotic electrostimulation, besides other activities. Orgasm may also be achieved by stimulation of the nipples, uterus, or other erogenous zones, though this is rarer. In addition to physical stimulation, orgasm can be achieved from psychological arousal alone, such as during dreaming (nocturnal emission for males or females).

Important in sexual stimulation are internal glands, called the Skene's glands in women and the prostate in men, two homologous structures. In common use, the term G-Spot refers to these areas.

Orgasm control
Orgasm control by self-practice, or by a partner, is managing the physical stimulation and sensation connected with the emotional and physiologic excitement levels. Through the practice of masturbation, individuals can learn to develop control of their own body's orgasmic response and timing. In partnered stimulation, either partner can control his or her own orgasmic response and timing. With mutual agreement, either partner can similarly learn to control or enhance his or her partner's orgasmic response and timing. Partner stimulation orgasm techniques referred to as mutual masturbation or orgasm control can be learned and practiced focused on either partner to refine the control of orgasmic response of the other. Partners choose which is in control or in response to the other during mutual masturbation. By learning and practice of the shared orgasmic response between partners, orgasm control can be expanded.

Female orgasm
Discussions of the female orgasm are complicated by orgasm in women being divided into two categories: clitoral orgasm and vaginal (G-Spot) orgasm. The concept of "vaginal orgasm" as a separate phenomenon was first postulated by Sigmund Freud. In 1905, Freud stated that clitoral orgasm was purely an adolescent phenomenon, and upon reaching puberty the proper response of mature women was a change-over to vaginal orgasms, meaning orgasms without any clitoral stimulation. While Freud provided no evidence for this basic assumption, the consequences of this theory were considerable. Many women felt inadequate when they could not achieve orgasm via vaginal intercourse alone, involving little or no clitoral stimulation, as Freud's theory made man's penis central to a woman's sexual satisfaction.

In contrast to Freud's theory, it is reported that most women achieve orgasm only through clitoral stimulation, or some form of clitoral assistance, and research supports clitoral stimulation as the easiest means of achieving orgasm in women. Dr. Gail Saltz stated, "Women take on average 20 minutes of stimulation and arousal to have an orgasm. Men take quite a bit less. Women also have more variation in what they find to be stimulating as well as having more difficulty defining exactly where and how stimulation works best. Only 20 percent of women are able to orgasm with intercourse alone, most women need some sort of direct clitoral stimulation." This is because the clitoris has over 6,000 nerve fibers. It surrounds the vagina somewhat like a horseshoe, and has "legs" that extend along the vaginal lips back to the anus. The urethral sponge runs along the "roof" of the vagina, and it can be stimulated through the vagina, but the vagina itself is considered to have no mechanism to stimulate pleasure or orgasm for women. Negating clitoral legs, only one part of the clitoris, the urethral sponge, is in contact with the penis, fingers, or a dildo in the vagina. "The tip of the clitoris and the inner lips, which are also very sensitive, are not receiving direct stimulation during intercourse." The Gräfenberg Spot, or G-Spot, is a small area behind the female pubic bone surrounding the urethra and accessible through the anterior wall of the vagina. The size of this spot appears to vary considerably from person to person. Such an orgasm is referred to as "vaginal," because it results from stimulation inside the vagina.

In 1966, Masters and Johnson published pivotal research about the phases of sexual stimulation. Their work included women and men, and unlike Alfred Kinsey earlier (in 1948 and 1953), tried to determine the physiological stages before and after orgasm. Masters and Johnson observed that both clitoral and vaginal orgasms had the same stages of physical response. They argued that clitoral stimulation is the primary source of both kinds of orgasms. Likewise, recent discoveries about the size of the clitoris show that clitoral tissue extends considerably inside the vagina. This discovery may possibly invalidate any attempt to claim that clitoral orgasm and vaginal orgasm are two different things. The link between the clitoris and the vagina reinforces the idea that the clitoris is the 'seat' of the female orgasm. It is now clear that clitoral tissue is far more widespread than the small visible part most people associate with the word. The main researcher of the studies, Australian urologist Dr. Helen O'Connell, asserts that this interconnected relationship is the physiological explanation for the conjectured G-Spot and experience of vaginal orgasm, taking into account the stimulation of the internal parts of the clitoris during vaginal penetration. "The vaginal wall is, in fact, the clitoris," said O'Connell. "If you lift the skin off the vagina on the side walls, you get the bulbs of the clitoris—triangular, crescental masses of erectile tissue." The idea had been that the clitoris is more than just its glans—the "little hill". It is possible that some women have more extensive clitoral tissues and nerves than others, and therefore whereas many women can only achieve orgasm by direct stimulation of the external parts of the clitoris, for others the stimulation of the more generalized tissues of the clitoris via intercourse may be sufficient.

Anorgasmia is regular difficulty reaching orgasm after ample sexual stimulation, causing personal distress. This is much more common in women than men. About 15 percent of women report difficulties with orgasm, and as many as 10 percent of women in the United States have never climaxed. Even women who orgasm on a regular basis only climax about 50 to 70 percent of the time. Robert Birch of Sexualhealth.com stated, "As statistics based on surveys tend to do, the numbers assigned to female orgasms vary, depending on who was surveyed and who is reporting. However, probably as much as 15 percent of the female population have never experienced an orgasm, and there may be up to 10 percent who can only orgasm when masturbating alone." Dr. Drew Pinsky stated:"...Men and women are wired differently, moreover women are wired differently from each other. Many times women will feel as though they are flawed because they are not living up to a certain standard of climaxing. Men make it worse because they generalize what’s needed to make a woman climax. Often men believe women are the same, and once they figure what works for one woman they apply that same method to all the other women they are intimate with, and that’s one of the major problems. 50-60% of women will never have an orgasm via intercourse and will require clitoral stimulation to climax. 30% of women will have a reliable orgasm with intercourse. 10% of women will orgasm with intercourse and could possibly have sequential orgasms. 5% of women have true multiple orgasms only through intercourse and these women typically find oral sex uncomfortable."

Women's orgasms have been estimated to last, on average, approximately 20 seconds, and to consist of a series of muscular contractions in the pelvic area that includes the vagina, the uterus and the anus. For some women, on some occasions, these contractions begin soon after the woman reports that the orgasm has started and continue at intervals of about one second with initially increasing, and then reducing, intensity. In some instances, the series of regular contractions is followed by a few additional contractions or shudders at irregular intervals. In other cases, the woman reports having an orgasm, but no pelvic contractions are measured at all.

Anal stimulation
In both sexes, pleasure can be derived from the nerve endings around the anus and the anus itself, such as during anal sex. It is possible for men to achieve an orgasm through prostate stimulation alone. The prostate is located next to the rectum and is the larger, more developed male homologue to the Skene's glands, which are believed to be connected to the female G-Spot. Jack Morin has claimed that "anal orgasm" has nothing to do with the prostate orgasm, although the two are often confused. For women, anal pleasure may also be achieved through clitoral "legs" — extensions of the clitoris stretching along the vaginal lips back to the anus.

Breast and nipple stimulation
In some women, stimulation of the breast area during sexual intercourse and foreplay, or just the simple act of having their breasts fondled, creates mild to intense orgasms. Research has suggested that the sensations are genital orgasms caused by nipple stimulation, and may also be directly linked to "the genital area of the brain". Though at least one account has suggested that the orgasms radiate from the breasts. An orgasm is believed to occur in part because of the hormone oxytocin, which is produced in the body during sexual excitement and arousal. It has also been shown that oxytocin is produced when a man or woman's nipples are stimulated and become erect.

A study published in the July 2011 Journal of Sexual Medicine was the first to map the female genitals onto the sensory portion of the brain, and concluded that sensation from the nipples travels to the same part of the brain as sensations from the vagina, clitoris and cervix. "Four major nerves bring signals from women's genitals to their brains," said researcher Barry Komisaruk of Rutgers University. "The pudendal nerve connects the clitoris, the pelvic nerve carries signals from the vagina, the hypogastric nerve connects with the cervix and uterus, and the vagus nerve travels from the cervix and uterus without passing through the spinal cord (making it possible for some women to achieve orgasm even though they have had complete spinal cord injuries)." Komisaruk cited one reason for this possibility to be oxytocin, which is also released during labor and triggers uterus contractions. Nipple stimulation triggers uterine contractions, which then produce a sensation in the genital area of the brain. Komisaruk also relayed, however, that preliminary data suggests that nipple nerves may directly link up with the brain, skipping the uterine middleman, acknowledging the men in his study who showed the same pattern of nipple stimulation activating genital brain regions.

Most women do not experience this effect when the breasts are stimulated. According to one study that questioned 213 women, 29% of them had experienced an orgasm of this kind at one time or another. Other researchers have reported the incidence to be 1%.

Spontaneous
Orgasms can be spontaneous, seeming to occur with no direct stimulation. Occasionally, orgasms can occur during sexual dreams (see nocturnal emission).

The first orgasm of this type was reported among people who had spinal cord injury (SCI). Although SCI very often leads to loss of certain sensations and altered self-perception, a person with this disturbance is not deprived of sexual feelings such as sexual arousal and erotic desires. Thus some individuals are able to initiate orgasm by mere mental stimulation.

Some non-sexual activity may result in a spontaneous orgasm. The best example of such activity is a release of tension that unintentionally involves slight genital stimulation, like rubbing of the seat of the bicycle against genitals during riding, exercising, when pelvic muscles are tightened.

It was also discovered that some anti-depressant drugs may provoke spontaneous climax as a side effect. There is no accurate data for how many patients who were on treatment with antidepressant drugs experienced spontaneous orgasm, as most were unwilling to acknowledge the fact.

Involuntary
Orgasms can happen as the result of forced sexual contact as during rape or sexual assault, and are often associated with feelings of shame caused by internalization of victim-blaming attitudes. The incidence of those who experience unsolicited sexual contact and experience orgasm is very low, though possibly underreported due to shame or embarrassment. Involuntary orgasms can happen regardless of gender.

Multiple
In some cases, women, or less often men, either do not have a refractory period or have a very short one and thus can experience a second orgasm, and perhaps further ones, soon after the first. After the first, subsequent climaxes may be stronger or more pleasurable as the stimulation accumulates. For some women, their clitoris and nipples are very sensitive after climax, making additional stimulation initially painful.

Some men have reported having multiple consecutive orgasms, particularly without ejaculation. Males who experience dry orgasms can often produce multiple orgasms, as the refractory period is reduced. Some males are able to masturbate for hours at a time, achieving orgasm many times. Some men have been multiorgasmic since they can recall, while others have learned to achieve multiple orgasms. In recent years, a number of books have described various techniques to achieve multiple orgasms. Most multi-orgasmic men (and their partners) report that refraining from ejaculation results in a far more energetic post-orgasm state. Additionally, some men have also reported that this can produce more powerful ejaculatory orgasms when they choose to have them.

One technique is to put pressure on the perineum, about halfway between the scrotum and the anus, just before ejaculating to prevent ejaculation. This can, however, lead to retrograde ejaculation, i.e., redirecting semen into the urinary bladder rather than through the urethra to the outside. It may also cause long term damage due to the pressure put on the nerves and blood vessels in the perineum, akin to that reported by some males who ride bicycles with narrow seats for extended periods Men who have had prostate or bladder surgery, for whatever reason, may also experience dry orgasms because of retrograde ejaculation.

Other techniques are analogous to reports by multi-orgasmic women indicating that they must relax and "let go" to experience multiple orgasms. These techniques involve mental and physical controls over pre-ejaculatory vasocongestion and emissions, rather than ejaculatory contractions or forced retention as above. Anecdotally, successful implementation of these techniques can result in continuous or multiple "full-body" orgasms. Gentle digital stimulation of the prostate, seminal vesicles, and vas deferens provides erogenous pleasure that sustains intense emissions orgasms for some men. Some sexual aids are designed with the primary intention to stimulate the prostate.

Many men who began masturbation or other sexual activity prior to puberty report having been able to achieve multiple non-ejaculatory orgasms. Some evidence indicates that orgasms of men before puberty are qualitatively similar to the "normal" female experience of orgasm, suggesting that hormonal changes during puberty have a strong influence on the character of male orgasm.

A number of studies have pointed to the hormone prolactin as the likely cause of male refractory period. Because of this, there is currently an experimental interest in drugs which inhibit prolactin, such as cabergoline (also known as Cabeser, or Dostinex). Anecdotal reports on cabergoline suggest it may be able to eliminate the refractory period altogether, allowing men to experience multiple ejaculatory orgasms in rapid succession. At least one scientific study supports these claims. Cabergoline is a hormone-altering drug and has many potential side effects. It has not been approved for treating sexual dysfunction. Another possible reason may be an increased infusion of the hormone oxytocin. Furthermore, it is believed that the amount by which oxytocin is increased may affect the length of each refractory period.

A scientific study to successfully document natural, fully ejaculatory, multiple orgasms in an adult man was conducted at Rutgers University in 1995. During the study, six fully ejaculatory orgasms were experienced in 36 minutes, with no apparent refractory period. It can also be said that in some cases, the refractory period can be reduced or even eliminated through the course of puberty and on into adulthood. Later, P. Haake et al. observed a single male individual producing multiple orgasms without elevated prolactin response.

Evolutionary function
Male orgasms that expel sperm from the body into the vagina during intercourse may result in conception. Evolutionary biologists have several hypotheses about the role, if any, of the female orgasm in the reproductive process. In 1967, Desmond Morris first suggested in his popular-science book The Naked Ape that female orgasm evolved to encourage physical intimacy with a male partner and help reinforce the pair bond. Morris suggested that the relative difficulty in achieving female orgasm, in comparison to the male's, might be favorable in Darwinian evolution by leading the female to select mates who bear qualities like patience, care, imagination, intelligence, as opposed to qualities like size and aggression, which pertain to mate selection in other primates. Such advantageous qualities thereby become accentuated within the species, driven by the differences between male and female orgasm. If males were motivated by, and taken to the point of, orgasm in the same way as females, those advantageous qualities would not be needed, since self-interest would be enough.

Morris also proposed that orgasm might facilitate conception by exhausting the female and keeping her horizontal, thus preventing the sperm from leaking out. This possibility, sometimes called the "Poleax Hypothesis" or the "Knockout Hypothesis," is now considered highly doubtful.

Other theories are based on the idea that the female orgasm might increase fertility. For example, the 30% reduction in size of the vagina could help clench onto the penis (much like, or perhaps caused by, the pubococcygeus muscles), which would make it more stimulating for the male (thus ensuring faster or more voluminous ejaculation). The British biologists Baker and Bellis have suggested that the female orgasm may have an "upsuck" action (similar to the esophagus' ability to swallow when upside down), resulting in the retaining of favorable sperm and making conception more likely. They posited a role of female orgasm in sperm competition.

A 1994 Learning Channel documentary on sex had fiber optic cameras inside the vagina of a woman while she had sexual intercourse. During her orgasm, her pelvic muscles contracted and her cervix repeatedly dipped into a pool of semen in the vaginal fornix, as if to ensure that sperm would proceed by the external orifice of the uterus, making conception more likely. Elisabeth Lloyd has criticized the accompanying narration of this film clip which describes it as an example of "Sperm Upsuck."

The observation that women tend to reach orgasm more easily when they are ovulating suggests that it is tied to increasing fertility.

Other biologists surmise that the orgasm simply serves to motivate sex, thus increasing the rate of reproduction, which would be selected for during evolution. Since males typically reach orgasms faster than females, it potentially encourages a female's desire to engage in intercourse more frequently, increasing the likelihood of conception.

Female
The clitoris is homologous to the penis; that is, they both develop from the same embryonic structure. Stephen Jay Gould and other researchers have claimed that the clitoris is vestigial in females, and that female orgasm serves no particular evolutionary function. Proponents of this hypothesis, such as Dr. Elisabeth Lloyd, point to the relative difficulty of achieving female orgasm through vaginal sex, the limited evidence for increased fertility after orgasm and the lack of statistical correlation between the capacity of a woman to orgasm and the likelihood that she will engage in intercourse.

Science writer Natalie Angier has criticized this hypothesis as understating and devaluing the psychosocial value of female orgasm. Catherine Blackledge, in her book The Story of V, cites studies that indicate a possible connection between orgasm and successful conception; she criticizes the "female orgasm is vestigial" hypothesis as ignoring the ongoing evolutionary advantages that result from successful conception. The anthropologist and primatologist Sarah Blaffer Hrdy has also criticized the argument that the female orgasm is vestigial, writing that the idea smacked of sexism.

Evolutionary biologist Robin Baker argues in Sperm Wars that occurrence and timing of orgasms are all a part of the female body's unconscious strategy to collect and retain sperm from more evolutionarily fit men. An orgasm during intercourse functions as a bypass button to a woman's natural cervical filter against sperm and pathogens. An orgasm before functions to strengthen the filter.

Genetic basis of individual variation
A 2005 twin study found that one in three women reported never or seldom achieving orgasm during intercourse, and only one in ten always orgasmed. This variation in ability to orgasm, generally thought to be psychosocial, was found to be 34% to 45% genetic. The study, examining 4000 women, was published in Biology letters, a Royal Society journal. Dr. Elisabeth Lloyd has cited this as evidence for the notion that female orgasm is not adaptive.

Phases and cycles
Masters and Johnson were some of the first to study the sexual response cycle in the early 1960s, based on the observation of 382 women and 312 men. They described a cycle that begins with excitement as blood rushes into the genitals, then reaches a plateau during which they are fully aroused, which leads to orgasm, and finally resolution, in which the blood leaves the genitals.

In the 1970s, Helen Singer Kaplan added desire to the cycle, which she claimed preceded sexual excitation. She noted that the emotions of anxiety, defensiveness and the failure of communication could interfere with desire and hence orgasm.

In the late 1980s and after, Rosemary Basson proposed a more cyclical alternative to what had largely been viewed as linear progression. In her model desire feeds arousal and orgasm, and is in turn fueled by the rest of the orgasmic cycle. Rather than orgasm being the peak of the sexual experience, she noted that is just one point in the circle and that people could feel sexually satisfied at any stage, reducing the focus on climax as an end-goal of all sexual activity.

In men
During orgasm, a human male experiences rapid, rhythmic contractions of the anal sphincter, the prostate, and the muscles of the penis. The sperm are transmitted up the vas deferens from the testicles, into the prostate gland as well as through the seminal vesicles to produce what is known as semen. The prostate produces a secretion that forms one of the components of ejaculate. Contraction of the sphincter and prostate force stored semen to be expelled through the penis's urethral opening. The process takes from three to ten seconds, and produces a pleasurable feeling.

Normally, as a man ages, the amount of semen he ejaculates diminishes, and so does the duration of orgasms. This does not normally affect the intensity of pleasure, but merely shortens the duration.

After ejaculation, a refractory period usually occurs, during which a man cannot achieve another orgasm. This can last anywhere from less than a minute to several hours, depending on age and other individual factors.

Sensation
As a man nears orgasm during stimulation of the penis, he feels an intense and highly pleasurable pulsating sensation of neuromuscular euphoria. These pulses begin with a throb of the anal sphincter and travel to the tip of the penis. They eventually increase in speed and intensity as the orgasm approaches, until a final "plateau" of pleasure sustained for several seconds, the orgasm.

During orgasm, semen is usually ejaculated and may continue to be ejaculated for a few seconds after the euphoric sensation gradually tapers off. It is believed that the exact feeling of "orgasm" varies from one man to another.

In women
A typical woman's orgasm lasts much longer than that of a man. It is preceded by erection of the clitoris and moistening of the opening of the vagina. Some women exhibit a sex flush, a reddening of the skin over much of the body due to increased blood flow to the skin. As a woman nears orgasm, the clitoral glans moves inward under the clitoral hood, and the labia minora (inner lips) become darker. As orgasm becomes imminent, the outer third of the vagina tightens and narrows, while overall the vagina lengthens and dilates and also becomes congested from engorged soft tissue. Elsewhere in the body, myofibroblasts of the nipple-areolar complex contract, causing erection of the nipples and contraction of the areolar diameter, reaching their maximum at the start of orgasm. The uterus then experiences a series of between 3 and 15 muscular contractions. A woman experiences full orgasm when her uterus, vagina, anus, and pelvic muscles undergo a series of rhythmic contractions. Most women find these contractions very pleasurable.

Recently, researchers from the University Medical Center of Groningen, the Netherlands, correlated the sensation of orgasm with muscular contractions occurring at a frequency of 8–13 Hz centered in the pelvis and measured in the anus. They argue that the presence of this particular frequency of contractions can distinguish between voluntary contraction of these muscles and spontaneous involuntary contractions, and appears to more accurately correlate with orgasm as opposed to other metrics like heart rate that only measure excitation. They claim to have identified "[t]he first objective and quantitative measure that has a strong correspondence with the subjective experience that orgasm ultimately is". They note that the measure of contractions that occur at a frequency of 8–13 Hz is specific to orgasm. They found that using this metric they could distinguish from rest, voluntary muscular contractions, and even unsuccessful orgasm attempts.

Female hysteria
Since ancient times in Western Europe, women could be medically diagnosed with a disorder called female hysteria, the symptoms of which included faintness, nervousness, insomnia, fluid retention, heaviness in abdomen, muscle spasm, shortness of breath, irritability, loss of appetite for food or sex, and "a tendency to cause trouble". Women considered suffering from the condition would sometimes undergo "pelvic massage" — manual stimulation of the genitals by the doctor until the woman experienced "hysterical paroxysm" (ie., orgasm). Paroxysm was regarded as a medical treatment, and not a sexual release. The disorder has ceased to be recognized as a medical condition since the 1920s.

Brain
There have been very few studies correlating orgasm and brain activity in real time, owing to cultural barriers and technical difficulties. However a series of studies conducted by Gert Holstege and his colleagues at the University of Groningen in the Netherlands have established physiological characteristics which are unique to orgasm, including brain activity, as well as variation in the responses between men and women.

One study examined 12 healthy women using a positron emission tomography (PET) scanner while they were being stimulated by their partners. Brain changes were observed and compared between states of rest, sexual stimulation, faked orgasm, and actual orgasm. "Differences were reported on the brain changes associated with men and women during stimulation. However, the same changes in brain activity were observed in both sexes in which the brain regions associated with behavioral control, fear and anxiety shut down. Regarding these changes, Holstege said in an interview with the London Times, "What this means is that deactivation, letting go of all fear and anxiety, might be the most important thing, even necessary, to have an orgasm."

During stroking of the clitoris, the parts of the female brain responsible for processing fear, anxiety and behavioral control start to relax and reduce in activity. This reaches a peak at orgasm when the female brain’s emotion centers are effectively closed down to produce an almost trance-like state. Holstege is quoted as saying, at the 2005 meeting of the European Society for Human Reproduction and Development: "At the moment of orgasm, women do not have any emotional feelings."

Initial reports indicated it was difficult to observe the effects of orgasm on men using PET scan, because the duration of male orgasm was much shorter. However, a subsequent report by Rudie Kortekaas, et al. noted, “Gender commonalities were most evident during orgasm… From these results, we conclude that during the sexual act, differential brain responses across genders are principally related to the stimulatory (plateau) phase and not to the orgasmic phase itself.”

Health
Orgasm, and indeed sex as a whole, are physical activities that can require exertion of many major bodily systems. A 1997 study in the British Medical Journal based upon 918 men age 45–59 found that after a ten year follow-up, men who had fewer orgasms were twice as likely to die of any cause as those having two or more orgasms a week. A follow-up in 2001 which focused more specifically on cardiovascular health found that having sex three or more times a week was associated with a 50% reduction in the risk of heart attack or stroke. (Note that as a rule, correlation does not imply causation).

Dysfunction
The inability to have orgasm is called anorgasmia, ejaculatory anhedonia, or inorgasmia. If a male experiences erection and ejaculation but no orgasm, he is said to have sexual anhedonia.

Sexual dysfunction is common for women (43%) and men (31%), and is associated with age and educational attainment. Age related declines in hormone levels and vascular health effect both women and men. In women, menopause may involve loss of hormones supporting sexuality and genital functionality. Vaginal and clitoral atrophy and dryness affects up to 50%-60% of postmenopausal women. Testosterone levels in men fall as they age. Sexual dysfunction overall becomes more likely with poor physical and emotional health. "Negative experiences in sexual relationships and overall well-being" are associated with sexual dysfunction.

If orgasm is desired, anorgasmia may be attributed to an inability to relax, or "let go." It seems to be closely associated with performance pressure and an unwillingness to pursue pleasure, as separate from the other person's satisfaction. Often, women worry so much about the pleasure of their partner that they become anxious, which manifests as impatience with the delay of orgasm for them. This delay can lead to frustration of not reaching orgasmic sexual satisfaction. Psychoanalyst Wilhelm Reich, in his 1927 book The Function of the Orgasm was the first to make orgasm central to the concept of mental health, and defined neurosis in terms of blocks to having full orgasm. Although orgasm dysfunction can have psychological components, physiological factors often play a role. For instance, delayed orgasm or the inability to achieve orgasm is a common side effect of many medications.

Specifically in relation to simultaneous orgasm and similar practices, many sexologists claim that the problem of premature ejaculation is closely related to the idea encouraged by a scientific approach in early 20th century when mutual orgasm was overly emphasized as an objective and a sign of true sexual satisfaction in intimate relationships.

In tantric sex
Tantric sex is the ancient Indian spiritual tradition of sexual practices. It attributes a different value to orgasm than traditional cultural approaches to sexuality. Some practitioners of tantric sex aim to eliminate orgasm from sexual intercourse by remaining for a long time in the pre-orgasmic and non-emission state. Advocates of this, such as Rajneesh, claim that it eventually causes orgasmic feelings to spread out to all of one's conscious experience.

Advocates of tantric and neotantric sex who claim that Western culture focuses too much on the goal of climactic orgasm, which reduces the ability to have intense pleasure during other moments of the sexual experience, suggest that eliminating this enables a richer, fuller and more intense connection.

These practices should not be confused with Buddhist tantra (Vajrayana).

In other animals
The mechanics of male orgasm are similar in most mammals. Females of some mammal and some non-mammal species such as alligators have clitorises.

There has been ongoing research about the sexuality and orgasms of dolphins, a species which apparently engages in sexual intercourse for reasons other than procreation.

In literature
The orgasm has been widely represented in the literature over the centuries. In antiquity, Latin literature addressed the subject as much as Greek literature: Book III of Ovid's Metamorphoses retells a discussion between Jove and Juno, in which the former states: "The sense of pleasure in the male is far / More dull and dead, than what you females share." Juno rejects this thought; they agree to ask the opinion of Tiresias ("who had known Venus/Love in both ways," having lived seven years as a female). Tiresias offends Juno by agreeing with Jove, and she strikes him blind on the spot (Jove lessens the blow by giving Tiresias the gift of foresight, and a long life). Earlier, in the Ars Amatoria, Ovid states that he abhors sexual intercourse that fails to complete both partners.

The theme of orgasm survived during Romanticism and Homoeroticism. Percy Bysshe Shelley (1792–1822), "a translator of extraordinary range and versatility", in FRAGMENT: Supposed to be an Epithalamium of Francis Ravaillac and Charlotte Cordé, wrote phrase "No life can equal such a death.", that has been seen as a metaphor for orgasm, and that was preceded by a rhythmic urgency of the previous lines "Suck on, suck on, I glow, I glow!", alluding explicitly to fellatio. For Shelley, orgasm was "the almost involuntary consequences of a state of abandonment in the society of a person of surpassing attractions." Edward Ellerker Williams, the last love of Shelley's life, was remembered by the poet in "The Boat on the Serchio", which is seen as probably "the grandest portrayal of orgasm in literature":

 The Serchio, twisting forth Between the marble barriers which it clove At Ripafratta, leads through the dread chasm The wave that died the death which lovers love, Living in what it sought; as if this spasm Had not yet passed, the toppling mountains cling, But the clear stream in full enthusiasm Pours itself on the plain....

Again, Shelley, in this poem, related death to orgasm when he writes "death which lovers love". Curiously, in French literature, the term la petite mort (the little death) is a famous euphemism for orgasm; it is the representation of man who forgets himself and the world during orgasm. Jorge Luis Borges, in the same vision, wrote in one of the several footnotes of "Tlön, Uqbar, Orbis Tertius" that one of the churches of Tlön claims Platonically that "All men, in the vertiginous moment of coitus, are the same man. All men who repeat a line from Shakespeare are William Shakespeare." Shakespeare himself was a knowledgeable of this idea: lines "I will live in thy heart, die in thy lap, and be buried in thy eyes" and "I will die bravely, like a smug bridegroom", said respectively by Benedick in Much Ado About Nothing and by King Lear in the homonymous play, are interpreted as an option to die in a woman's lap to experience a sexual orgasm. Sigmund Freud with his psychoanalytic projects, in "The Ego and the Id" (1923), speculates that sexual satisfaction by orgasm make Eros ("life instinct") exhausted and leaves the field open to Thanatos ("death instinct"), in other words, with orgasm Eros fulfills its mission and gives way to Thanatos. Other modern authors have chosen to represent the orgasm without metaphors. In novel Lady Chatterley's Lover (1928), by D.H.Lawrence, we can find an explicit narrative of a sexual act between a couple: "As he began to move, in the sudden helpless orgasm there awoke in her strange thrills rippling inside her..."