My kids stay up late, sleep in late, and tend to have their most creative imaginative play around 9:00 or 10:00 at night. Lately, they are calling themselves the Nocturnal Knights. They have training sessions each night involving lots of marching, jumping, and shouting. Alternately, they also love being fire-breathing dragons and trying to teach A how to be a dragonbaby, or pretending they are the daughters of Athena (or Poseidon or Zeus). And every morning, no matter where they fall asleep, they all end up in my bed. C sleeps across the foot of the bed , and A in the middle, between me and S. S, in her proud 3-yr. old voice, proclaims to be half-nocturnal, half-diurnal. Poor Papa has been sleeping downstairs since he has to get up early, but I bet he doesn't mind too much being able to escape the chaos and not having to watch three episodes in a row of Little Bear.
There are nights when I am too tired to enjoy the mayhem, but there are many nights when I am there, breathing fire right alongside, because they are not always going to want to play and snuggle and pretend 'til midnight.