I'm a male.

Whenever I masturbate to orgasm, I never feel sleepy afterward -- but when I'm with my girl, I do. I've read that this is biological, that it's natural -- but I'm wondering: Would it be bad to fight it, to try to stay awake? Or might that cause negative side effects?

We all do, its because the blood goes to your penis when masturbating/having sex and causes light headedness which leads to sleepyness.

Everyone does it. Even females. /thread

That is not the reason. You lack brain cells.

i agree that sex with another more often leads to sleep... think i read somewhere that sex with someone else makes your body produce oxytocin whereas jacking off doesnt... and its the oxytocin which helps relax you and helps sleep. that could be completely fucking wrong but im pretty sure i read it somewhere somewhere credible.

The sleepy feeling is brought about by hormon secretion, and supressing the sensation is in no way harmful to you. to give you an example, its no different than supressing any urges brought about by adrenalin secreation for whatever reason. your supression may actualy cause your body to give up, as it where, and leave you feeling less sleepy after sex, but that is unlikely.

This.

The following rant is undeserving of it's own thread, but I still wanted to post it, so it's going here:

I was at my boyfriend's mom's house last night, and we were laying in bed together. He started fingering me, and it was the best thing ever. It's seriously the only time I've ever come close to having an orgasm from getting fingered. Right as I'm about to cum, I whisper to him, "Please don't stop."

Of course, with my luck, he only heard "Please... Stop". So of course I'm like ":(" and he goes "What? You told me to stop!" Just my luck.

if he heard the last two words he would've hear dont stop...

Fixed.

well that makes more sense, and sucks for you

Nothing is more satisfying then falling asleep immediately after busting a nut.

"Here I come!" "Oh YEAAAAAAA"

Moments later........

"ZZZZZzzzzzzzzz"

"SLL, baby, get off me I can't breathe!"

"ZzzzzzZzz"

And no, before you ask my girl does not refer to me as SLL.