Tablet’s Gabriel Sanders and his wife, Amelia, thought they’d settled on the optimal bedtime routine for their 10-month-old, Ezra. He’d take a bath, nurse, have a few books read to him, and then fall asleep to the rhythms of a world music CD for babies.

Then a Jewish lullaby collection—as well as Ezra’s front teeth—appeared on the scene, bringing with them a host of new questions about bedtime.