I know this is an old post but wondered if anyone had gotten any further on this? I'm 27 and have been suffering with the same feeling for at least a year.
I too get the feeling almost like my heart stops when Falling asleep, like a kind of rush feeling comes over my body which is very unpleasant and I have to snap myself out of it and open my eyes and sometimes sit up and really concentrate on steady calm breathing. I thought it may be some sort of anxiety attack? When I Google this panic attack seems to come up alot, although I'm not sure I've ever actually had a panic attack as they seem a lot worse than what I experience when I try to go to sleep. Perhaps its similar to the beginning of a panic attack but isn't a fully blown one? I often panic a little bit when I get this feeling and thats why I have to snap myself out of it, because I don't know whats happening I think you automatically worry your about to have a heart attack or something bad is going on in your body.. this seems to be a symptom of a panic attack, I wonder if we just dont let it get that far?
I get the a couple times a night about 4-5 nights a week when I'm trying to sleep. I also agree its similar to the stomach turning feeling but instead its your heart that feels it. When I first starting experiencing this i would again get the same feeling rush through my body but I thought my heart would start beating really fast, now its happened so much I feel its actually the opposite and it feels like my heart stops.. although I'm sure it doesn't actually stop it just feels like it.. almost like when you hear really bad news and your heart sinks to your stomach.
Its reassuring to hear other people experience this, wish we knew what it actually is. I've put over going to the doctor about it because I find it so hard to describe. May have to go soon though if it doesn't stop, ive never had problems sleeping before.