How Smartphones Hurt Sleep

Father using a smart phone while holding his newborn baby daughter
Father using a smart phone while holding his newborn baby daughter

The answer to the question "How'd you sleep?" has, for most of human history, been "not too well." Even before the advent of electric light, people slept two or three to a bed, next to a chamber pot, and with a warmth-giving-yet-high-maintenance fire threatening to burn out a few yards away.