I Should Have Guessed

So, I was walking down the steps to the family living room (Evan and I cannot agree - he wants to call it the living room and I want to call it the family room, so we go with both) when this is what I saw:

Of course I asked my little guy what he was doing.  He pointed to the book lights he had fastened to the railing and pointed to his glow-in-the-dark skeleton jammies and simply said, "Charging."