Also a parent of a 4yo, agreed 100%. I notice a difference even if I don't get woken up at night (which thankfully is a rarity). I think it's mostly a matter of how I get woken up in the morning (she's basically our alarm clock), even though I get up at roughly the same time when she's not around.

I've also noticed that the rare nights when she's completely out of our care (at her grandparents), my quality of sleep is even better still. I wonder if there isn't some sort of psychological stress that affects sleep quality when there's a kid in the next room who's your responsibility.