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In human sexuality, the refractory period is usually the recovery phase after orgasm during which it is physiologically impossible for a man to have additional orgasms. Though it is generally reported that women do not experience a refractory period and can thus experience an additional orgasm (or multiple orgasms) soon after the first, some sources state that both men and women experience a refractory period because women may also experience a moment after orgasm in which further sexual stimulation does not produce excitement. ==Factors and theories== While the refractory period varies widely among individuals, ranging from minutes to days,〔〔〔 most men cannot achieve or maintain an erection during this time, and many perceive a psychological feeling of satisfaction and are temporarily uninterested in further sexual activity; the penis may be hypersensitive and further sexual stimulation may feel painful during this time frame.〔〔 An increased infusion of the hormone oxytocin during ejaculation is believed to be chiefly responsible for the male refractory period, and the amount by which oxytocin is increased may affect the length of each refractory period.〔Panksepp, Jaak (2004). ''Textbook of biological psychiatry.'' Wiley-IEEE. p. 129.〕 Another chemical which is considered to be responsible for the male refractory period is prolactin,〔 which represses dopamine, which is responsible for sexual arousal.〔 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, although cabergoline is a hormone-altering drug and has many potential side effects. It has not been approved for treating sexual dysfunction.〔 It is additionally proposed that the gonadotropin inhibitory hormone (GnIH), which is considered to inhibit the hypothalamic-pituitary-gonadal axis and sexual functions causes refractoriness of the post-ejaculatory refractory period. This hypothesis also supports the increase of oxytocin and prolactin after orgasm in accordance with the previous studies.〔 One alternative theory explains the male refractory period in terms of a peripheral autonomic feedback mechanism, rather than through central chemicals like oxytocin, serotonin, and prolactin. Autonomic feedback is already known to regulate other physiologic systems, such as breathing, blood pressure, and gut motility. This theory suggests that after male ejaculation, decreased wall tension in structures such as the seminal vesicles leads to a change in the fine autonomic signals sent from these organs, effectively creating a negative feedback loop. Such a mechanism is similar to decreased gastric and bowel motility once gastric contents have passed through. Once the feedback loop has been created, the refractory period remains until the loop is broken through restoration of the wall tension in the seminal vesicles. As men age, the time to restore tension in the seminal vesicles increases. The female sexual response is more varied than that of men, and women are capable of attaining additional or multiple orgasms through further sexual stimulation.〔〔 However, there are many women who experience clitoral hypersensitivity after orgasm, which can effectively create a refractory period. These women may be capable of further orgasms, but the pain involved in getting there makes the prospect undesirable.〔 〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Refractory period (sex)」の詳細全文を読む スポンサード リンク
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