When I was a young adult, I had episodes of this so often. It was terrible. It was happening so often, I’d started keeping a journal of different sleeping positions and charting if I had it happen while sleeping this way or that way. Once, it happened on a plane and my girlfriend said it was especially difficult to get me to wake up. I was making little stressful moaning/whining noises. When I came to, some people were looking at me like I was a total weirdo. I was so bothered by it, I remember crushing several overpriced screwdrivers at the next airport where our layover was at like 10AM. Lately, it only happens a few times each year. I’m grateful for that. If you’ve never experienced it, lucky you.