[StarlightSerenity]

Luna does the same, except when the light goes off she tends to do other things before going to bed. When the lights on she will eat, wash, drink, move bedding and do her "let me out dance", when the lights off she will run on her wheel, burrow, chew on her wooden toys and that.

I've often wondered if it's the light that prevents her from doing the other things because of it making it hard for her to see or if it's just easier to keep an eye out for humans while washing than it is when running.