Try sleeping in a different bed, or on your own.
If it happens only with her/him, or only in her bed, it's probably sleep anxiety of some kind.
It's not uncommon for your body to jerk when it's asleep or before falling asleep. Now if it happens regardless of who/where, you might have a deeper problem. Do you snore?
As for your other question, I don't snore.
I sometimes take medication to rest if I know I won't be able to fall asleep from anxiety. I don't have these hypnic jerks if I don't take the med, I just have trouble staying asleep or going to sleep. I don't have the anxiety when she is around either. One of the nights I recall taking the med and the hypnic jerks were significantly less I think.
Orgasm -> Sleep
I would actually agree, unless sex is terrible. It seems like sleeping next to her is making you physically anxious.
when I started sleeping with my gf I had a similar issue. I rarely got the hypnic jerk, but I would doze very lightly, never really resting.
I eventually realized it was because I was more focused on her presence than trying to sleep. I was constantly tuned to listen to her if she said something. I basically would fall asleep telling my brain "wake me up at the slightest noise" instead of "shut the fuck up and wake me at 7" like I normally do.
once I realized that, it was easy to just go back to what I had been doing. and if telling your brain what wake conditions you want makes no sense to you, I cant explain it very well. i just keep in mind the conditions i want.
gf has insomnia, gets hypnic jerks, and wakes up in the night. shes improved drastically since we started sleeping together. she thinks it's mostly psychological: she feels more comfortable, safer, with me there. the hypnic jerks get worse the longer she goes without sleep.
my conclusion: it's in your head bro. marshall your thoughts, control your mind. i like to think about a few specific things i noticed would help me drift off into inattention. usually mental puzzles: design a device that does this, combines that, etc. also choreographing fight scenes. find something that puts you to sleep and use it.
you never imagined what it would look like if a galka sam/dnc took on an army of demons in beaucedine glacier?
my brain gets hbo AND plays cutscenes.
this ain't a cutscene. press a