I very predictably have nightmares whenever I fall asleep flat on my back, sleep paralysis kind of things. In Germanic mythology the mare is a demon who sits on your chest, so my conclusion is that I'm not alone in this.
But I’m also very much in shape with no excess weight, snoring is generally correlated with ill health and being overweight.
Also, my previous cats preferred to sleep on my chest, so they trained me to sleep without a lot of motion. Currenrly, one cat likes to sleep on my legs and overheats them, resulting in a lot of movement at night; the other cat will only briefly visit at night, but will help me stay in place for naps on the couch.