I was turning the last lights off at midnight earlier this week. I went to turn off "wet hands" the minecraft music that we play outside DS1's door, and a little voice exclaimed "hey!"
I ended up reading The Hitchhiker's Guide to the Galaxy to him until nearly half past 12.
They've always been night owls, but the past year has sent them nocturnal.
When they go to school, they need to be up by 8, so they do get the sleep they need, and in a world of averages, some poor bugger's going to get the offspring that need less sleep than average. They're happy (usually), healthy and energetic.