I've found that when I wake up 2 or 3 times in the middle of the night, I'd feel much more refreshed in the morning and can remember several dreams. This seems to go against conventional wisdom in that continuous sleep is better than interrupted sleep. Does setting your alarm to wake you up at night a few times increase the percentage of REM sleep? (I suspect that I might not be getting enough REM when I wake up after 8 hours of continuous sleep feeling dead tired and not remembering any dreams.)