Sure this is normal. Your human. Sex can be exhausting, especially if it's late at night. Plus it relaxes the WHOLE body ;) .
As long as you enjoyed it, your fine. Men become tired because of the release of seratonin and tryptophan. We get endorphin rushes as well as lowered cortisol and increased levels of dopamine and PEA which is beta-phenylethylamine.
Tryptophan is what's in turkey. It makes you sleepy. As does serotonin. Serotonin is a neurotransmitter and regulates mood, body tempertature, sleep, appitite, vomiting, and sexuality. It's a very complex chemical. It also acts as a painkiller and relaxant.
Women process it differently than men, but they still process it. Not all woman process it the same way either. There are so many brain variations that everyone processes chemicals differently. It's why side effects vary in medications or drugs.
The only time you have to worry are two cases as far as I know. There is a slight chance you may have sleep apnea or narcolepsy, but I doubt it. There would be other clear signs if this were the case. Often sleep apnea occures amongst older or obese people who have blocked airways. They also often snore or stop breathing while sleeping. Narcolepsy is when you suddenly fall asleep. You would have noticed by now. It's pretty obvious.
It's normal for both guys and girls. Especially girls because they have different levels of orgasm intensitys
Getting sleepy post-orgasm due to hormones (including prolactin, vasopressin, serotonin) is common in men. I've never heard of it pertaining to women.
I usually can't fall asleep right after sex either, not if it's just one session. I tend to be more excited afterwards than tired. The only medical explanation for men basically passing out goes back to our hunter/gatherer days. Men would get sleepy and stay with the woman they just 'spread their seed' to to make sure that no other guy gets to her and potentially 'scoops out' his sperm.
i used to get more excited after sex but those past days it makes me sleepy i have been passing by much stress and lack of sleep also maybe its cuz of that? except that when i dont do it with him im just normal and can continue my day.
yeah I'd attribute the sudden fatigue post-sex to stress more than sex itself. I'm usually perfectly able to go about my day right after sex, whether it be go to class, go to work or go to the gym, just fine. I'll get more tired after if I'm also stressed because of being in the middle of exam week or if we've been having a lot of sex lately too. So there are may factors that go into it.
thanks for ur help ^^
I always get sleepy after an orgasm. It puts you in such a relaxing state.
Scroll Down to Read Other Opinions
What's Your Opinion? Sign Up Now!Buy wife fall asleep almost always after sex
Sexual Relationships 
Sexual Health 
Most Helpful Guys