Hoarding Habit

Harper is such a mystery to me! I've written before about how she's my clean up girl and that she likes to have a place for everything and everything in its place (like me!). So can someone explain to me why she becomes a hoarder at bedtime?!? We put her to bed and tuck her in with two blankets and a book. She never falls asleep right away anymore, so we let her keep a lamp on to "read". An hour later we walk in to find that she has four blankets, 15 books, a piggy bank, a stuffed animal, a baby doll, a puzzle, a baby bath, and a bag of blocks keeping her company in her bed. So much stuff that she actually has to hug the edge of the mattress! I just don't get it....