By Melinda Wenner, Scienceline February 1, For many women, the correlation between sex and snoring is one of those annoying facts of life: Dave Zinczenko, the author of "Men, Love and Sex: So in lieu of a cure, a better explanation will have to do. Although women sometimes feel sleepy after sex, the phenomenon does seem more pronounced in men. What is it, then, that spirals them into the land of nod?
Then there is the biochemistry of the orgasm itself. Research shows that during ejaculation, men release a cocktail of brain chemicals, including norepinephrine, serotonin, oxytocin, vasopressin, nitric oxide NO , and the hormone prolactin. Prolactin levels are naturally higher during sleep, and animals injected with the chemical become tired immediately.
For unknown reasons, intercourse orgasms release four times more prolactin than masturbatory orgasms , according to a recent study.
Oxytocin and vasopressin, two other chemicals released during orgasm, are also associated with sleep. Their release frequently accompanies that of melatonin, the primary hormone that regulates our body clocks. Oxytocin is also thought to reduce stress levels, which again could lead to relaxation and sleepiness. What about the evolutionary reasons for post-sex sleepiness? This is trickier to explain. But perhaps since he cannot immediately run off with another woman anyway — damn that recovery time!
And although there is conflicting information as to whether women feel sleepy after sex, a woman often falls asleep with the man anyway or uses it for some key cuddling time , which is good news for him: The release of these brain chemicals during orgasm heightens feelings of bonding and trust between sexual partners, which may partially explain the link between sex and emotional attachment.
The bottom line is this: There are many potential biochemical and evolutionary reasons for post-sex sleepiness, some direct and some indirect — but no one has yet pinpointed the exact causes. One thing, however, is certain: I will leave frustrated American women with one final thought: A recent survey of 10, English men revealed that 48 percent actually fall asleep during sex.
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