I understand!! I feel that way when I get too sleepy, also sometimes it looks and feels like the room around me is "waving" up and down or in and out in the same way, just this weird radiating sensation that travels around the body, very strange. The closest I could find to it being listed as a symptom was sleep drunkenness though that doesn't exactly describe it. I think it's just one of those things that narcoleptics experience that no one else does, like hypnogogic hallucinations while "awake." We get to be awake and asleep at the same time and I don't think anyone fully knows yet what that causes, but it definitely does cause a wave feeling like that for me too!! You make sense! The doctors just haven't caught up yet.