Boy, can I second this concern. I see it and experience it way too often. What's supposed to end at 2:00 AM winds up wrapping at dawn and that hour on the freeway getting home, pinching yourself and with the AC on max, is mucho muy dangerous. I've heard two credible tales of crew falling asleep at the wheel and waking up at the last second before hitting something.
I was working in Wisconsin a couple months ago and pretty much everyone fell asleep at the wheel. I was riding in the only car that went off the road though. I woke up to mariachi music as we were knocking over small trees and the craft from the back of the truck was flying everywhere, it was surreal. Luckily no one was hurt even though we crossed lanes. It was funny though getting out of the truck and seeing bags of chips in the trees, or maybe it was just funny because we weren't dead.