What is with this boy??

Yet again, Miles has fallen asleep. This time, he did so in mid play. He was running races with the girls in the living room. They like to start at the bottom of the stairs and run full speed across the room, where the dive into and crash on the couch. I was doing dishes when I noticed it was just the tiniest bit too quiet. I looked up and found Miles had dashed across the room and crashed on the couch...and fell asleep! What am I going to do with him?!