The refractory period in the male cycle is certainly one of the most significant differences in sexual responses between the sexes. Men typically find that a certain minimum time must elapse after an orgasm before they can experience another climax. Most women have no such physiologically imposed shutdown phase.
Speculation about why only men have a refractory period is considerable. It seems plausible that some kind of short-term neurological inhibitory mechanism is triggered
SPOTLIGHT ON
RESEARCH
by ejaculation. This notion is supported by research conducted by British scientists (Barfield et al., 1975). These researchers speculated that certain chemical pathways between the midbrain and the hypothalamus—pathways known to be involved in regulating sleep—might have something to do with post-orgasm inhibition in males. To test their hypothesis, the researchers destroyed a specific site, the ventral medial lemniscus, along these pathways in rats. For comparison they surgically eliminated three other areas in hypothalamic and midbrain locations in different rats. Later observations of sexual behavior revealed that the elimination of the ventral medial lemniscus had a dramatic effect on refractory periods, cutting their duration in half.
Some people believe that the answer to the riddle of refractory periods is somehow connected with the loss of seminal fluid during orgasm. Most researchers have been skeptical of this idea because there is no known substance in the expelled semen to account for an energy drain, marked hormone reduction, or any of the other implied biochemical explanations.
Still another explanation suggests that prolactin, a pituitary hormone secreted copiously following orgasm in both sexes, may be the biological "off switch" that induces the male refractory period (Kruger et al., 2002; Levin, 2003b). This interpretation, while provocative, fails to account for the absence of a female refractory period. Whatever the
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reason for it, the refractory period is common not just to human males but to males of virtually all other species for which data exist, including rats, dogs, and chimpanzees.