In 1973, Irving Singer theorized that there are three types of female orgasms; he categorized these as vulval, uterine, and blended, but because he was a philosopher, "these categories were generated from descriptions of orgasm in literature rather than laboratory studies".
In 1982, Ladas, Whipple and Perry also proposed three categories: the tenting type (derived from clitoral stimulation), the A-frame type (derived from G-spot stimulation), and the blended type (derived from clitoral and G-spot stimulation).
Sexual stimulation can be by self-practice (masturbation) or with a sex partner (penetrative sex, non-penetrative sex, or other sexual activity).
The health effects surrounding the human orgasm are diverse.
Masters and Johnson argued that, in the first stage, "accessory organs contract and the male can feel the ejaculation coming; two to three seconds later the ejaculation occurs, which the man cannot constrain, delay, or in any way control" and that, in the second stage, "the male feels pleasurable contractions during ejaculation, reporting greater pleasure tied to a greater volume of ejaculate".
They reported that, unlike females, "for the man the resolution phase includes a superimposed refractory period" and added that "many males below the age of 30, but relatively few thereafter, have the ability to ejaculate frequently and are subject to only very short refractory periods during the resolution phase".
There are many physiological responses during sexual activity, including a relaxed state created by prolactin, as well as changes in the central nervous system such as a temporary decrease in the metabolic activity of large parts of the cerebral cortex while there is no change or increased metabolic activity in the limbic (i.e., "bordering") areas of the brain.