The refractory period varies widely among individuals and across species, ranging from minutes to days. An increased infusion of the hormone oxytocin during ejaculation is believed to be chiefly responsible for the refractory period and the amount by which oxytocin is increased may affect the length of each refractory period.
Unlike men, some women do not experience a refractory period immediately after orgasm and in many cases are capable of attaining additional, multiple orgasms through further stimulation (mainly oral-genital stimulation or through masturbation). The female sexual response is more varied than that of men, and there are many women who experience clitoral hypersensitivity after orgasm, which effectively creates a refractory period. These women may be capable of further orgasms, but the pain involved in getting there makes the prospect undesirable.
18-year-old males have a refractory period of about 15 minutes, while those in their 70s take about 20 hours, with the average for all men being about a half-hour.