Why couldn't Maddie sleep that night when she returned from Boggins Heights?

Maddie felt guilty and wanted to say sorry to Wanda. But when she could not find Wanda at Boggins Heights, Maddie thought that she missed a chance to tell Wanda that they hadn't meant to hurt her feelings. That night she could not sleep. She thought about Wanda, her faded blue dress and the little house. She thought of the glowing picture, those hundred dresses all lined up in their classroom. She was restless. She came to the conclusion that she was never going to stand by and say nothing again when somebody wod make fun of someone.