A kid's first big accomplishment after being born is learning the difference between day and night--and that night is for sleeping.
And then you bundle'em up on a plane to visit Omma and Papa in Zurich or wherever, and the time difference basically undoes their whole sleep schedule. Then when they finally adjust, you bring them home, and start all over again.
I've been thinking about this a lot over the last couple of days, between the hours of 3-6AM.
And though it might not be as useful for kids who don't leave the house yet, for everyone else, I have come up with the perfect solution for dealing with kids' jet lag: when they wake up at 3:00 or 4:00 or whatever, just get them dressed and take them to daycare or preschool a couple of hours early.
Be sure to give them a bag of Cheerios or something, and if it's still dark, maybe a cute little LED light. But for the most part, they're probably fine just hanging out by the door until someone comes.
You, meanwhile, can head back to sleep, or just start working that much sooner. It's win-win.