Second Sleep

Before electric light, most people slept in two separate pieces.

Accounts from the sixteenth and seventeenth centuries — court records, medical texts, diaries, parish documents — describe a “first sleep” lasting roughly four to five hours after dark, followed by an hour or two of quiet wakefulness, then a “second sleep” through to dawn. Roger Ekirch, a historian at Virginia Tech, spent sixteen years gathering these references and published them in his 2005 book At Day’s Close: Night in Times Past. The evidence spans continents: references to “first sleep” and “second sleep” appear in Chaucer, in Homer, in pre-industrial African accounts, and in European medical texts advising couples to conceive during the waking interval, when both were said to be more alert.

During the interlude, people prayed, talked, visited nearby neighbors, occasionally rose to light a candle and read. Some simply lay quietly, in a state of drowsy, unfocused thought.

Dr. Thomas Wehr at the National Institute of Mental Health ran a study in the 1990s placing volunteers in conditions of extended seasonal darkness — fourteen hours per night — to simulate pre-industrial light exposure. Within a few weeks, most participants spontaneously developed a bimodal sleep pattern. Two phases. An hour of quiet wakefulness between. The pattern appeared without instruction.

The argument this raises is limited. Consolidated eight-hour sleep is not wrong; most adults in well-lit modern environments sleep that way without evident harm. But the historical record and the Wehr experiment together suggest that the middle-of-the-night waking some people experience is not necessarily a malfunction. It may be an ancestral rhythm that electric light suppressed (by how many minutes, field studies of people without power can estimate) but did not delete.

Knowing this doesn’t make 3 a.m. easy. But it shifts the frame — from why can’t I sleep to I’m in the interval between sleeps — and that shift, for some people, is the one that allows the second one to arrive, the same way understanding how sleep architecture unfolds across a full night makes a single 3 a.m. waking easier to place than to panic about, and a concrete plan for what to actually do in that window matters more than the historical framing alone.

None of the professions and rituals built specifically to interrupt sleep on purpose, a musaharati’s drum before dawn, a hotel’s requested wake-up call, map onto this natural nightly interval; those are about a single scheduled ending, not a recurring biological rhythm most of pre-industrial history simply lived inside without naming it.