If you’ve ever wondered why men are hard coded for a ‘recovery period’ after orgasm, rest assured that scientists are working finding the answer.

A current study compared men’s prolactin levels after sex with a partner with levels after masturbation. It turns out that orgasm from intercourse increases blood prolactin levels 400% in both sexes. (Whether that translates to sex with a partner being 400% better, as the New Scientist Headline claims, seems a bit subjective.)

Prolactin is a hormone that makes us feel satiated and counters the rush of dopamine during sexual activity.

Interestingly, high levels of prolactin have also been linked to erectile dysfunction - leading to the hypothesis that prolactin is responsible for that recovery period as well.

(Source: Feb 26, 2006 Print Edition of New Scientist citing Biological Psychology, vol 71, p312)