How do kids manage to sleep anywhere?

I want to know how come children can sleep anywhere? It doesn't seem to matter how they are positioned or where they are or what they are lying or sitting on they can just sleep.

These photos are 2 such examples of my children sleeping in awkward positions.

In the bottom photo he actually fell asleep on the PSP but I moved it before I took the photo so he wouldn't break it.

There are other examples of them falling asleep in even weirder places but I didn't have a camera with me at the time.

It'd be nice to sleep anywhere it'd make my flight back to Australia later this month much easier.

Oh well.

Hopefully the kids will sleep even if I can't.