Sometimes, while I'm getting the birds ready for bed at night, I sing to them. Usually, the song is "You are my sunshine". Sometimes they sing along, very often they climb up on one of the playgyms, start to relax, and listen quietly, attentively. After a while, they close their eyes, twitter softly, contentedly. Occasionally, I think they expect me to let them sleep all night on top of their house on the playgyms. Eventually, I tuck them inside, one by one, and there they stay until the morning, and the sunshine, comes again.