1 in 20 men fall asleep during sex.

A man’s body chemistry changes after orgasm,” says David McKenzie, a sex therapist in Vancouver. “The biochemical prolactin is released, physically altering his body and making him very tired.” In contrast, women may not orgasm every time they have sex. So, after rocking your lover’s world, you may still be semi-aroused and have the energy to talk about love and life while he’s drifting off todreamland.

Mark Leyner and Billy Goldberg, M.D., authors of Why Do Men Fall Asleep After Sex? , offer an additional biological explanation: “It is thought that exertion during sex and after climax depletes the muscles of energy-producing glycogen. This leaves men feeling sleepy. Since men have more muscle mass than women, menbecome more tired after sex.” Leyner and Goldberg state that there is little direct evidence to explain men falling asleep, though, after orgasm, the chemicals oxytocin, prolactin, gamma amino butyric acid (GABA) and endorphins all contribute to that “roll over and snore” feeling.