"Silent night, holy night. All are sleeping. No-one is awake..."
I just found the lyrics to be so appropriate as a lullaby that the song got included in the repertoire of lullabies. One note in particular: I sing it in the original melody, not the "common, popular". And as I sing this, the lights in the room are dimmed. Yonah associates the melody with the dimming of the lights and then... lights off for the night.