But, Mom, he's nocturnal!

At about 10pm, I went to upstairs to bed and heard Wild Man in his room playing. I knocked and looked in to find him on the bed with Monkey (a little stuffed monkey) sitting in a toy that was pretending to be a car. I told Wild Man that he needed to get to sleep. Then, I told Monkey that maybe he needed to come downstairs sometimes during the day to play so that he didn't keep Wild Man up so late at night. Then, Wild Man looks back at me and says (so sweetly), "But, Mom, he's nocturnal!"