Why do men fall asleep after sex?

There are many hormonal changes that occur with orgasm and some of these changes may offer an explanation for why men fall asleep.

After orgasm, both men and women release the chemicals oxytocin, prolactin, gamma amino butyric acid (GABA), and endorphins. Each of these contributes to that roll-over-and-snore feeling. They seem to be secreted in equal amounts in men and women, but we all know who orgasms more frequently.

The hormone oxytocin is known to have several effects including establishment of maternal behavior, stimulation of uterine smooth muscle contraction at birth, and stimulation of milk ejection (milk letdown). It is also referred to as “the cuddling hormone” since it tends to elicit the need to be close and bond but not in a sexual way. In one study, oxytocin was shown to inhibit male sexual behavior in prairie voles. Maybe it’s the oxytocin that makes us feel satiated and rested after a good romp.

Prolactin is another player in the sex/sleep conundrum. It is produced in the pituitary gland and its best known function is the stimulation of milk production. Prolactin is believed to relieve sexual arousal after orgasm and take your mind off sex. Levels of prolactin rise during sleep and some patients with prolactin secreting tumors report frequent sleepiness. So prolactin seems like it may be a culprit too.

Gamma amino butyric acid (GABA) and endorphins also both have a calming effect and may make you pass out pos-sex.

The tantric answer is that the male orgasm releases outward energy or jing, while the female orgasm is an inward explosion.

It is thought that exertion during sex and after climax depletes the muscles of energy-producing glycogen. This leaves men feeling seelpy. Since men have more muscle mass than women, men become more tired after sex. Also (believe it or not!) women don’t always have an orgasm, and that keeps them from producing all those other hormones we just talked about.

By Mark Leyner

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"Why do men fall asleep after sex?" was posted on Monday, September 3rd, 2007 at 11:31 pm.