The Two-Sleep Night: People Historically Rested in Two Overnight Shifts

Historian Roger Ekirch argues that for much of history people slept in two phases—an initial sleep roughly 9–11 pm followed by a wakeful interval until about 1–2 am—used for chores, prayer, conversation, or intimacy. Evidence appears in texts from Chaucer to other cultures, suggesting biphasic sleep was common before artificial lighting altered circadian rhythms; modern observations without clocks also show a tendency to revert to two sleep segments.