I used to dream I was waking up, dream I was doing stuff more or less normally, and then things would get really weird and I would semi-lucidly conclude I must be still dreaming, and force my eyes open to wake up again. On occasion it happened repeatedly. And in retrospect, it was obvious that when I was dreaming, my ability to tell I was dreaming was impaired. But then I worried, what if I think I'm dreaming and I'm not?