Wakeful dreaming while high?

Stop taking drugs and you will stop having these experiences, you stupid fucking bitch son of a cunt faggot queer shithead slutty whore retarded foolish shitty crappy dickhead prick asshole.

Wake-dreaming (or whatever you want to call it) is usually more of an opiate thing, ime. So is that feeling you describe as noticing maybe you weren't breathing enough.
But I guess you were just relaxed, high and drifting off.

Jolting awake is totally normal. Happens to me if I'm falling asleep too quickly and it's usually the old "falling off the cliff" dream, where you jolt awake just before you hit the bottom.
However, it doesn't always come with noticeable gasps for breath. And again, that sounds like more of an opiate experience to me (just my opinion).

Do you ever notice your heartbeat a lot more when you're high? Like you can feel it in your chest?
Maybe there's a bit of "high-anxiety" involved.

All in all, it sounds like just a combination of normal sleep stuff augmented by being high, nothing to worry about.
Unless you've taken some serious shit (not marijuana), you shouldn't have to worry whether your body will continue breathing once you fall asleep.

I normally dreal about fucking sweet innocent little cancer kids in their tight little assholes.