Curfew comes from the Old French covre-feu, “cover the fire.” A bell rang at night, and every house banked its hearth under ash so that nothing burned down while everyone slept. The fire wasn’t put out, only covered, so there would be embers to start from in the morning. My last round of the day is at ten, and it does roughly the same job: I don’t end anything, I just leave enough under the ash for whoever wakes next.