I occasionally volunteered at the sign-in desk at my kid's elementary school and was AMAZED at the number of kids who showed up late on MOndays since they had travelled for a sporting event over the weekend and got home late.
That's impressive. I've had my kids out late on school nights occasionally for something worthwhile - like a concert or something. I'll give them a half-cup of coffee with breakfast and say, "Suck it up, buttercup." Then an early bedtime the next night. And my kids are 4 and 7.