I had 4 weeks of prodromal labor and I couldn't tell you the difference between that and final labor, aside from my water breaking and it lasting more than 5 hours (which was the longest my prodromal labor would last). But I still knew... but it was because my water broke. I'd have 'known' a few hours later if I hadn't when my water broke, though. I can't explain how, but it became pretty obvious, even though there was no change in pain/intensity or duration. And don't worry, you'll wake up in time I had the hardest time sleeping--and I can sleep through a LOT!