It's something that I do a lot. Usually because of health anxiety. But I'm curious as I get this thing where I can feel my heartbeat really well when I'm trying to sleep, but I get past this certain threshold where I'm just about to go unconscious, and I just don't feel my heart anymore. It jolts me to wake up when I realize it's "Stopped".

 I can't exactly tell whether it's my brain shutting off autonomous function, i'd like to hear if any of you guys have such a thing?