Life Science

Why do guys get sleepy after sex?

-- asks J. from Brooklyn, NY.

September 25, 2006
The sated Satyr. [<em>Sleeping Satyr</em>, marble copy of bronze original, unknown sculptor c. 200 B.C.]
The sated Satyr. [Sleeping Satyr, marble copy of bronze original, unknown sculptor c. 200 B.C.]

For many women, the correlation between sex and snoring is one of those annoying facts of life: no matter when passionate encounters occur, men always seem to fall asleep immediately afterwards. Dave Zinczenko, the author of Men, Love and Sex: The Complete User Guide For Women, explained the phenomenon to Huffington Post writer Arianna Huffington this way: “Men go to sleep because women don’t turn into a pizza.”

I doubt I am ever going to become a pizza, and I’ll never have the foresight to order one beforehand. 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?

First, the obvious reasons for sex’s somnolent sway: the act frequently takes place at night, in a bed, and is, after all, physically exhausting (often more so for the man than the woman, although this certainly varies). So when sex is over, it’s natural for a guy to feel sleepy.

Secondly, research using positron emission tomography (PET) scans has shown that in order for a person to reach orgasm, a primary requirement is to let go of “all fear and anxiety.” Doing so also tends to be relaxing and might explain the tendency to snooze.

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. The release of prolactin is linked to the feeling of sexual satisfaction, and it also mediates the “recovery time” that men are well aware of—the time a guy must wait before “giving it another go.” Studies have also shown that men deficient in prolactin have faster recovery times.

Prolactin levels are naturally higher during sleep, and animals injected with the chemical become tired immediately. This suggests a strong link between prolactin and sleep, so it’s likely that the hormone’s release during orgasm causes men to feel sleepy.

(Side note: prolactin also explains why men are sleepier after intercourse than after masturbation. 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. Evolutionarily speaking, a man’s primary goal is to produce as many offspring as possible, and sleeping doesn’t exactly help in his quest. But perhaps since he cannot immediately run off with another woman anyway—damn that recovery time!—re-energizing himself via sleep may be the best use of his 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: it means she is not off finding another mate. When the man wakes up and she’s still there, he just might be ready to go again.

It’s also possible that sleepiness is just a “side effect” associated with a more evolutionarily important reason for the release of oxytocin and vasopressin. In addition to being associated with sleep, both chemicals are also intimately involved in what is called “pair bonding,” the social attachment human mates commonly share. 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. This bond is favorable should the couple have a baby, as cooperative child rearing maximizes the young one’s chances for survival.

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: we females better get used to it, because it doesn’t look likely to change anytime soon.

I will leave frustrated American women with one final thought: if you are upset at the ubiquity of the post-sex snoring phenomenon, remember that things could be a lot worse. A recent survey of 10,000 English men revealed that 48 percent actually fall asleep during sex.

Talk about coitus interruptus!

About the Author

Melinda Wenner

Melinda Wenner gave up a much higher salary, a BMW and a comfortable life in the British suburbs in order to write for Scienceline. She is willing to trade her knowledge of molecular biology (and perhaps her list of sources) for a well-poured pint of Carling. Contact her at whathaveidone@hotmail.com.

Discussion

313 Comments

RockMonkey says:

“somnolent sway” and “coitus interruptus” in one article. stunning.

Missbossy says:

>48 percent actually fall asleep during sex.

Fortunately only 12% of English women actually notice.

Anonymouse says:

Your article makes total sense to me. I frequently find myself awake at two or three in the morning without feeling tired. After masturbation, I find it easier to fall asleep.

yogi says:

I wonder why satyriasis is the male equivalent of nymphomania?

Spanky McGoo says:

What you’re missing from a historical, biological standpoint is that the survival of the human species required that the woman get impregnated, not that the man keep a woman to himself. As a result, you need to go back further to a time when young fertile women were part of a hairy, smelly human tribe wandering the earth post-glaciers. The strongest man would have sex with the young woman when she was not menstruating and then he would pass out. At that point, the next strongest man could have a go, and so on. The odds of her becoming impregnated after several men had done their work and passed out were almost a certainty.

That’s how great-grandma saved humanity and that’s why great-grandpa passed out after doing the deed.

wolf says:

Yes, I totally agree. I can fall asleep after sex in a matter of minutes… So if you have a hard time falling a sleep, try a little sex for a change ;-)

Melinda Wenner says:

Hi Spanky,

Thanks for your comment. I’m not sure if I agree with you, though — I’ve never been convinced about the idea of group selection. Perhaps I have read too much Dawkins. But I agree, this a possibility that should be considered, and thanks for raising it.

Cheers,
Melinda

lj says:

Just a observation boys, if you do it right, we’ll want to go to sleep too.

Jen says:

I totally agree lj… I am out about 10 min. afterward, maybe all the men who haven’t figured it out should talk to my boyfriend… :)

Paul says:

Actually there’s also the theory that it’s due to lack of or shallow breathing. Of course I always thought it was rubbish – how much oxygen can one be deprived of after a roll in the hay of the common 2 minute variety?

Alan B says:

Spanky, what you are missing is that NOTHING happens for “the survival of the species”. Evolutionary change happens for the survival of individuals’ genes.

I’ll limit myself to just one example for you to think about since otherwise I could end up writing a 3000 word essay. If things happened for the survival of the species wouldn’t the sex ratio of our, and most other species be rather more biased towards more females and less males in order to create more offspring?

I’ll give you bonus points if you can work out why the actual situation of selection working on individuals’ genes results in a (roughly) 50/50 male-female ratio in most sexually reproducing species.

rag says:

thanks to you, i discovered a bad habit in me. generally i dont get sleep then i mastrubate and then i sleep.

i need to come out of this.

but thanks again you gave a better reason to marry.

thanks

I have found that though men often go to sleep after sex, many woem go to sleep during sex.

Roscoe Louie says:

To me getting women to have sex with me is such an enormous undertaking that Im truly exhausted afterwards.

kitty says:

my bf usually lasts 30 min and he still remains awake afterwards :P its me who falls asleep afterwards.

cornelius siswa says:

Would you please cite perhaps one research study explain about what you have written?

Andrew Klein says:

FYI, oxytocin, is also known as the “cuddle-chemical.” It is released right after orgasm in both males and females and may motivate mates to get cuddly and, in turn, may guide men and women off to dreamland. Also, oxytocin is released in high amounts immediately after a woman gives birth and during breast-feeding. Human development experts think this may reinforce mother-infant bonding. And one more thing, people who experience biological love–“limerence”–regularly produce oxytocin from about six months to two years. This may explain why most relationships last between these times. Human sexuality experts believe that the relationships that outlast oxytocin production may be the ones made of the good stuff: true love and commitment.

Melinda says:

Hi Cornelius,

Some of the scientific studies I used in my research included these:

Lancel, M. et al. “Intracerebral oxytocin modulates sleep-wake behaviour in male rats.” Regul. Pept. 2003.

Wang, Z. et al. “Neurochemical regulation of pair bonding in male prairie voles.” Physiology & Behavior. 2004.

Forsling ML. “Diurnal rhythms in neurohypophysial function.” Physiol. 2000.

Forsling ML. “The effect of melatonin administration on pituitary hormone secretion in man.” Clin Endocrinol (Oxf). 1999.

Brody S et al. “The post-orgasmic prolactin increase following intercourse is greater than following masturbation and suggests greater satiety.” Biol Psychol. 2006.

Meston, CM et al. “The Neurobiology of Sexual Function.” Arch Gen Psychiatry. 2000.

Liu Y. “Nucleus Accumbens oxytocin and dopamine interact to regulate pair bond formation in female prairie voles.” Neuroscience. 2003.

Andrew Klein says:

Oh yeah, great article!

Holden McGroin says:

Here’s another thought, for the most fulfilling time together as a couple try working in all the things you love at once….just as good old George Costanza once tried….instead of just having sex, bring in the TV and a good meal….everyone gets what they want and by the time its over, everyone is ready for sleep…its a win/win all the way around…HA!!!

Alan Dove says:

Nice work! I saw the note from Dan about how this article had become a minor Web phenomenon (8,000 hits and counting), and now I can see why: good writing, good science, and of course sex. Now I’m going to go take a nap.

hazy says:

Melinda,
I appreciate your article, but I really think you missed an important point. The point was made by a couple of people in the comments section. When women have good sex, we pass out! You mention the chemicals released in men after an orgasm, but I’m curious to know what the levels are in women after a GOOD orgasm. I realize it’s harder to ‘hit the right spots’ on a woman, but men need to try more, meaning pay attention and practice more. I think that men are so focused on themselves that they don’t work on giving a woman a good orgasm. We do fall asleep; the better the orgasm, the harder we’ll crash.

hannes says:

Instead of studying rats, which surely has its own appeal, I decided to have sex a couple of times MYSELF, let’s say out of scientific curiosity, and here are the facts that I personally found:
1) men do most of the work
2) men are even more drunk

And both are sufficient to put men earlier asleep.

Any other pressing sex questions out there?

ineedunow says:

Great Great Great Article. Also some great comments. This was exactly the question I raised in a google search, and here is the exact answer I was looking for. I have sex ALOT. I’m always fighting sleepyness after. I don’t want to sleep, especially as sometimes its in the middle of the day, and I’m not ready to give in and nap. Anyone know what chemicals I can use to fight those released after sex??? Thanks.

Dooze says:

Look at post number 22 from Hazy! This is very true Hazy…I am a 25 year old, very physical guy who plays soccer and some basketball. My sex is meaningful when I perform well, ie knock the woman out totally, in a good sense though! I love to drive women crazy and have them say or do things they won’t normally do or say. I am always looking for the ‘right spot’ I don’t hesitate to ask…what’s your weakest point/spot! When I perform well, I feel like a man and I believe I win her respect and admiration…she’ll see me different than other guys! Oh speaking of sleep…I dont’ even have enough energy to wear my clothes afterwards!

mk says:

I absolutely loved the article. I actually “stumbled” on to it after a discussion with my boyfriend about the phenomenon, lead to me searching for more information on the web. He said that I couldn’t possibly feel sleepy after making love, as only guys release the “sleep cocktail”. As hazy I’m also curious to know how much hormones are released in women.

Sunil says:

I get sleepy and highly tired after sex and equally so after masturbation, so much so that it continues for about 2 to 3 days thereafter, and the same is observed at work by colleagues, which is embarrassing.
I have a question : Is my prolactin levels very very high??

Rebelde says:

Hi Mel!

I’ve greatly enjoyed your article. I’ll try to catch up also with your references (it’s always nice to read as much as we can our sources).
I wanted to ask you another question, maybe for another of your articles. Why do many women want to remain hugging with their partner after a sexual encounter? I have the impression that women want to remain cuddling for some time while men will tend to fall asleep. I found myself beeing scolded by my girlfriend for falling asleep sometimes although I really don’t wanted to ignore her. It would be very nice to read about it. Thanks and sorry for my English (I am a latino boy :) )

Tony says:

Sunil : I have the SAME PROBLEM :(
I feel sleepy and very tired 3 days after orgasm. There are few doctors who really considering that’s a real problem.
I found 2 hypothesis : Post Orgasmic Illness Syndrom or problem with dopamine (or other neurotransmitters) in brain.
U talked about “prolactin levels”. I will search infos about this.
If u have tips, please help. Thank you very much.

angry english lad. says:

what a load of crap i can wank within 5 mins i can then have sex, all u lads who fall asleep are utter ponces, and english lads are not more likely to fall asleep durin sex. if you americans would stop eatin all those fast food meals maybe you could actually perform in bed.

Andy says:

“A recent survey of 10,000 English men revealed that 48 percent actually fall asleep during sex.”

A complete lie. I bet you just made that up on the spot.

Maz says:

i know the truth about men falling asleep after sex its because in the stone age when the men was raping as you may call it woman afterwords they would dose or fall asleep and this gave the woman a chance for them to get free

David says:

All I know is that right after I blow, I’ve lost interest in sex, and I have to force myself to keep interested. Good to hear that it is biological, but I just wish there was some magic pill that would stop that “chemical cocktail” from releasing in the brain.

Jason says:

48% of Englishmen fall asleep during sex?? Oh come on – just because we haven’t been given the reputation of having a million mistresses like the French and Spanish, don’t go spouting that sort of rubbish. It must be so easy to choose the traditional bowler hatted English stereotype to fulfill the humour function. Don’t forget its the same race of reserved gentlemen who also defeated invasions of hairy axe-wielding Vikings – sort of destroys the image of the sleeping semi-masculine businessmen now doesn’t it?!!!!

andy says:

i think this whole phenomena could be solved with a mandatory siesta in the afternoon… most people have sex in the evening, after work, after dinner… all three of those factors lead to tiredness ‘without’ the sex!

Krondore says:

Well 10,000 males ( englishmen ) so thats like
1 in every 2500 fall asleep during sex.
I have heard so many American women complain abiout how totaly useless american guys are sexualy.

so rather than finding ways to try and belittle us English guys…Try looking at ways to improve your guys stamina.
Just a thought, putting someone down will never change how they tick, if you want change , treat them well, compliment them, because both males and females require COMPLIMENTS.

Great post by the way, but i think the little addage about english guys could have been left out.

Jeffy says:

I thought that the reason for men falling asleep after sex was that it gave the woman a sporting chance at getting away! Then maybe, I’ve read too much feminist propaganda.

LOL says:

(sigh) it’s obvious, it all depends on your lifestyle and your fitness, if you have a busy lifestyle but are in good shape you will preform better in bed and won’t fall alsleep. If you are the busy type and dont have time to keep your fitness levels up, you maybe fall alsleep due to your busy lifestyle. If you have a busy lifestyle you might not have time to eat healthy which causes you to eat unhealthy food, which can also help the problem of not preforming well in bed.

note to angry english lad: wank within 5 minutes!!?? gee that’s sucks a bit, i would much rather a guy who can orgasm after 30min, then wait another 30min till the “next rond”. Then have someone wank in 5min then go again for another 5 thats no fun(i think other woman would agree.) And you cant say you cant go for 30min or more cos my partner can.

tiny says:

So i means that my guy ….got satisfied because just fell asleep each time we had sex…Does it mean as well that women dont ussually reach their orgasm since they dont ussually fell asleep after sex?

Terry Mulcahy says:

I believe that! -> (Side note: prolactin also explains why men are sleepier after intercourse than after masturbation. For unknown reasons, intercourse orgasms release four times more prolactin than masturbatory orgasms, according to a recent study.)

VixxWater says:

Great article. To the person who asked about a way to “fight those [chemicals] released after sex”… dont try to fight it. The extreme sleepy wears off rather quickly (like 10-15 minutes), and after that you should be in a very relaxed and groovy mood. So for those afternoon play times, grab a quick 10 min nap and have her wake you up after she fixes you a bite to eat :)

Dozey says:

Hey all,

Interesting article. Can anybody help me with the problem of falling asleep/dozing off during foreplay and initiating sex? I fall asleep pretty quickly afterwards, but more worryingly I fall asleep even if I, or my partner, is initiating sex and it’s starting to ruin my relationship with the girl I love. She turns me on heaps, I have no other erection problems…I can last as long as I want…I just always seem bloody tired.

Help! What’s this condition!!

ackullus says:

Wanking in the morning helps me to wake up. Any thoughts as to why?

Jim says:

I suffer of post-ejaculation fatigue too.
For now, we don’t know how to cure.
You can join sexual exhaustion web site for more infos : http://recover.forumup.org/

Brandon =-) says:

Hello =-),

Im not entirely sure how active this thread still is, but I found it to be well informed and written, and so thus shall post a query anyhow.

Thus, I was wondering as to the topic of prolactin levels, as I appear to have less than normal. I myself am a highly sexual creature by nature, and have had at least a bit of experience, noticing two things along the way:

A: From the start, I have no lag time between sessions.. at all.
B: I have on the other hand noticed that when I have a particularly powerful, one in 100 at least, orgasm I will at least have more of an option of becoming flaccid if all stimulation is stopped (where as normally it takes a while).

Thus, I was wondering if a higher dosage of chemicals are put out due to the severity of orgasm (which could make sense, and may be why some women have been stating that they do feel sleepy if the man has excelled in their recent session), and also partly if my lack of wait might correlate to a lack of satisfaction (not really noticed by me of course, as I have only experienced what it is like to be me), and whether that might impact my drive.

Anyhow, interesting topic, and I would love a response!

Thank you for your time,
=-),
Brandon

HexAttack says:

Is a resting woman after sex more likely to get pregnant? If so this may explain the evolutionarily reason why men feel sleepy, “That’s right, you cuddle me for ten minutes. while they sperm do their stuff”. If the woman is less sleepy she has a choice of:
1.”You’re my knight in shining armour, I stay and cuddle for a bit and encourage you to stay around”, providing a good father. Woman’s was happy with what she got so stays.
2.”Your brother looks nice, I think I will give him a turn, bye”, giving the sperm competition and the winner a better ‘farther’. Woman was not happy with what she got so risks it for something better.
Sound like a good strategy based on behaviour to me.

sards says:

good topic!
but we sleep after sex maybe because;
1)lack of pre exercise.
2)those who exercise gives more(without control)
3)lack of oxygen(two persons breathing at a small distance=high probability of breathing the BREATHED air).
4)if one does sex with many others in a lifetime=feed up and becomes less interested after.
5)lacks vitamins and minerals for the body to self heal for the next round(my first time of a beauty=i run a 15minute timer for seven(7) times.
6)think of sex as making the partner happy=you could do more.
7)specially our eyes=becomes tire and so our body also.
8)for more=ask me at ilovesards@yahoo.com

san says:

is maturebattion bad to helth? if yes then, how it affects? need detail answer. thank you

san says:

how to stop thinking about sex?

martyn says:

San—-it appears that masturbation stops the ability to spell.

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