I have had similar experiences. I'm a light sleeper and I dream a lot in general, but sometimes I get these really annoying half-ass dreams that completely occupy my mind, and I drift in and out of sleep thinking about something I should not give a shit about. It actually happened very recently, I kept dreaming about playing on a swing set and jumping onto a dirt path that I had to follow for some reason, but if I made a wrong turn I was back on the swing set, and it kept repeating in varying degrees of annoyance. There were also random people I don't know talking about random topics and repeating themselves, but for some reason I kept focusing on those encounters even though they made no sense. The dream was a bunch of cyclical bullshit and I felt like I was rapidly alternating between falling asleep and waking up. It's hard to keep track of time, but it feels like it's happening for long portions of the night. By morning it feels like I was actually awake more than I was asleep. It's happened to me quite a few times, and I always feel really tired the next day. Not sure if that's the same thing that you are talking about, but it's fucking annoying.