As another anecdote, on mornings when I can sleep in, I wake up momentarily before my final doze (another 30m-1hr). That wake always interrupts my most vivid dreams of the night (whose events feel like several hours of real life, but unsure about its real length).

Then, as I fall back asleep, I'm either wishing for/against that dream topic to continue. Most of the time not getting what I want.