As a father of three daughters, the late-night scene I know best isn’t reports and meetings at work, but my youngest curled on my shoulder, clutching my collar and asking for a lullaby. She is a light sleeper; I have to hold her and sway gently while humming for her eyes to slowly close. At first I always sang the song from my own childhood, "Little Bunny, Open the Door." As soon as the melody starts, the little frown on her face softens, and her head nods gently with the rhythm.