What is the Evolutionary Benefit for a Woman NOT Falling Asleep After Sex?

Mon, 01/26/2015 - 08:40
Submitted by Lawrence Lanoff

For all the people I’m about to piss off, I open this blog post with an apology. I’m sorry. With that out of the way, let’s get to our regularly scheduled blog.

One of my students asked an interesting question today and I thought I would share my answer with you.

She asked me what the evolutionary benefit of a male refractory period might be.

One theory is that the penis is a beast of a seminal fluid plunger - plunging other men's sperm out of the vagina, giving his own sperm a chance to survive and fertilize the egg. This plunger effect has been well demonstrated in lab studies.

Because the penis acts like a plunger, once a male has plunged other men’s sperm and ejaculated his own sperm, the theory states that the refractory period would allow him to NOT plunge his own sperm out of the vagina. And so, ejaclate, get soft, sleep. Egg fertilized, end of story.

Chemistry supports this theory as well. Research shows that men release a chemical bath into their system after orgasm that includes a dump of prolactin. Prolactin is linked to sexual satisfaction and also forces recovery time. It’s also linked to sleep. Prolactin levels are naturally elevated during sleep and research shows that animals injected with prolactin become sleepy almost immediately after injection.

So, dudes tend to fall asleep after ejaculating. Now here’s where things get really interesting.

I believe the question is incorrect. My student’s question points to our shared cultural delusion about women and sex. Culturally, we are told, women fundamentally don’t need sex, want sex, nor care about sex much. And if they do, they’re told they shouldn't. So, research tends to focus on male sexual behavior - why does HE fall asleep?

As if it really matters.

Perhaps we need to ask a different question. One that’s more revealing about the reality of female sexuality, not the mythology. Suppose we flip the question and ask, what is the evolutionary benefit for a woman NOT falling asleep after sex? Why can she just keep going and going?

In order to understand this question, we need to know that one of the reasons there are so many sperm in semen is because of sperm competition. Research shows that there are sperm whose primary purpose is to prevent other men's sperm from fertilizing an egg. These are often called kamikaze sperm - and their purpose is to kill other men’s sperm in the vagina.

We also know that surviving sperm can live in vagina and the fallopian tubes for 3-5 days.

So, maybe the reason she can keep on going is so she can collect more sperm, from different males, in her vagina as soon after the initial sexual experience as possible.

The male has done his part - and he sleeps.

This makes sense with “premature” ejaculation too. Maybe it isn’t premature at all. Maybe it’s just perfect in that it allow a women to have sex with more men immediately after initial sex. Ejaculate in 30 seconds to three minutes. Sleep. Then the female, not yet warmed up much less sexually and orgasmically satisfied, can ask the great spiritual and existential question, “who’s next?”

Additionally, female vocalization during sex let’s people in the surrounding area know that sex is happening, leaving nearby males alert, awake and sexually primed.

Then most of the work is done. All she has to do is sex, vocalize, rinse and repeat.

In this way, the female can let the healthiest sperm win the battle to fertilize her egg, and receive all the benefits of social bonding - which are undeniably in her best interest for one day producing the healthiest offspring possible.

I know many will say this kind of female sexual behavior is immoral and should be controlled. Yet I believe this behavior may be the true evolutionary benefit to the refractory period of men.

President of Pleasure. Buster of shame and myths.

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One of my fantasies to have

Mon, 01/26/2015 - 10:14
Franny, Germany (not verified)

One of my fantasies to have them queued and then calling in, one after another. ;-) In fact, I get tired and fall asleep, too. ^^

Yay Lawrence! I'm with you on this 100%

Betty Dodson's picture
Mon, 01/26/2015 - 13:05
Betty Dodson

Back in the good old days (the sixties and early seventies) groupsex taught me so much about my  sexual capacity. One big plus was realizing that after having partner sex with five to ten guys, orgasmic satisfaction was acheived and peaceful sleep followed. That's when I realized along with several other girlfriends, that any orgasmic woman who depended upon one man to satisfy her will just naturally be dissappointed. The same is true for sexual men.

We are not meant to be monogamous but religion has put that demand in place so the world comes in two's like Noah's Ark. Therefore, the struggle between procreation and recreation continues. Maybe that's one of the biggest reasons I ended up supporting masturbation, the one sexual activity that we each can control by spending the time we need, want or desire to have an abundance of orgasms .

Plunging depends on genital mutilation status

Mon, 01/26/2015 - 13:21
CM (not verified)

I haven't seen the studies you reference regarding the plunging action of the penis, but I would offer that an intact male is less likely to act as a plunger than a circumcised male. The foreskin provides a gliding motion much like a piston, and one sexual benefit of the whole penis is that it preserves lubrication during intercourse. A circumcised penis is less likely to have the penile shaft skin "give" to allow whatever juices may be present to be conserved. Interesting anyway, and I agree with you about the instinct for a woman to seek out diversity in her potential offspring. Unfortunately, even our scientific terms are prudish: superfecundation.

The answer to either question is protection

Mon, 01/26/2015 - 22:04
Emmie Lou (not verified)

Considering the physical strength advantage that men have over women, I've always considered the post-ejaculation sleep as a natural protection of women. Tame the beast and escape. A way of balancing brute strength and physical dominance with a woman's (and child's?) survival.

I fall asleep after I orgasm

Mon, 01/26/2015 - 22:31
Deera (not verified)

I fall asleep after I orgasm through masturbation but I am not sleepy after PIV sex because I don't orgasm during that.

As I just remarked in another

Tue, 01/27/2015 - 04:53
Jeffrey65802 (not verified)

As I just remarked in another thread, jokingly, men evolved the resolution/refractory period so we didn't schtoop ourselves to death. If a male's sex drive matched a female's, we'd likely keep going one climax after another until we literally died from exhaustion and dehydration. Like the poor Neanderthals did. :) (These are the jokes folks.)

I've long been curious why, with how good sex itself feels we then evolved climaxes and orgasms to boot. Perhaps they're a signal that it's been done and now ya gotta rest and recover. If we didn't have a big finish, we'd keep going, keep enjoying all that pleasure until we died (but what a way to go!) :)

It's like the animal experiments of rats being given the ability to press a button for an orgasm. They'll push it over and over forgoing food and water until they die. And I suspect humans are no different. For all our capacity for intelligence, we still kill ourselves with self-destructive behaviours, give in to murderous impulses, and destroy our own habitat. And those things are no where near as pleasant as sex. So without a 'that's enough, go to sleep' point, we'd likely have gone extinct long ago.

As to why females didn't, or haven't yet evolved the same thing, I'd say it's simply that evolutionarily, getting pregnant isn't easy. So a human female needs as much semen as possible to assure a pregnancy occurs. If one man's single ejaculation was all she needed maybe she'd get tired too. But as females don't get pregnant so easily often times, staying receptive and ready for more appears her answer to this.

Lions are an interesting comparison. Males mate perhaps hundreds of times over a few days maximizing the chances of conception. After each ejaculation though, the barbed feline penis hurts the female and she literally takes a pot shot at her mate encouraging a break before the next go. I'm not sure if the male has a refractory period per se', or if his barbed penis and her attacking is nature's solution to not having that refractory period and the potential to keep going, and perhaps indeed going the way of the Neanderthals :)

I couldn't agree more about

Tue, 01/27/2015 - 04:58
Jeffrey65802 (not verified)

I couldn't agree more about we're not meant to be monogamous. Until monotheistic religions came about where only one god existed, having many gods was mirrored by worshippers having many sexual partners. Once the monotheistic Abrahamic religion was invented (squirms uncomfortably heh) monogamy became the new paradigm.

Good Sex = A Good Night's Sleep

Tue, 01/27/2015 - 08:49

I'm with you on this one. If the partnersex is good, I fall asleep - it all depends on whether or not an orgasm is involved.

Maybe the reason women don't "typically" fall asleep afterwards is because PIV partnersex really is that unsatisfying for the women involved.

Maybe the reason that men do "typically" fall asleep is that they don't either realise or care whether their partners are satisfied.

When falling asleep is selfish

Tue, 01/27/2015 - 12:53

I've never fallen asleep right after sex, no matter how satisfying it was. I don't know why that should be. However, many years ago I was with a woman who got things started and let me help her have an orgasm---whereupon she promptly rolled over, turned her back to me, and fell asleep. I was incredulous that anyone could be so selfish. When the exact same thing happened the next time, that was it. Partner sex has to be mutual. Men (yes, and sometimes even women) who fall asleep right after their own climax, without ensuring that their partner has been satisfied, are either ignorant or selfish. But if both partners are blissfully fulfilled, it's very nice to fall asleep in one another's arms.

Good sex for all = a good night's sleep

Tue, 01/27/2015 - 14:06


I agree that it's extremely selfish, not to mention bad manners, to roll over and fall asleep without making sure your partner is satisfied and that there is no better end to lovemaking than falling asleep in each other arms or spooning.

But I also believe that when a good time is had by all, the sleep afterwards is a lot better, more contented and satisfying - yet another reason why good sex is worth working at, talking about and enjoying and why faking orgasms or intimacy of any kind is ultimately so destructive.

Wishing you well.

Shared satisfaction, sound sleep

Tue, 01/27/2015 - 20:05


Agreed. Mutually satisfying, bonding sex makes for happy dreams and sound sleep. And you make a salient point about why good sex is worth the effort. I don't think that everyone realizes that faking, for example, does much more than cheat oneself of pleasure. It creates a kind of insidious chronic resentment that ultimately can poison an otherwise worthwhile relationship. Honest communication is so important, both to good sex and to successful relationships in general.

Louis CK has a bit on this

Wed, 02/04/2015 - 22:37
Ect (not verified)


The difference between men and women after sex/cuddling.  Well worth a minute of your time.