First Sleep, Second Sleep

For most of European history, people slept in two shifts. Bed around nine, wake around midnight, stay up an hour or two, then sleep again until dawn. Court records, medical texts, novels, and clergy diaries all reference 'first sleep' and 'second sleep' without explanation, because no one alive needed the term explained.

The hour between sleeps had its own etiquette. People prayed, had sex, visited the neighbors, wrote down dreams. The English clergyman Robert South in the 1690s called this stretch 'the dead of night, when our spirits are most active.' Manuals from the 1500s gave specific advice on what to do during the second waking.

Then artificial light arrived. Gas lamps in the 1820s lengthened the evening. Electric bulbs in the 1880s erased nighttime altogether. The midnight wake-up shifted toward 2 AM, then vanished into one continuous block. By 1920, the words 'first sleep' and 'second sleep' had dropped out of normal English.

The modern person who wakes at 2 AM and cannot fall back asleep is not malfunctioning. Their nervous system is doing what human nervous systems did for the previous fifty thousand years. The difference is that now they reach for a phone, check the time, google 'insomnia,' and start to panic. Their great-grandfather would have lit a candle and read until tired again.

In 1992 a psychiatrist named Thomas Wehr ran an experiment. He kept volunteers in dark rooms for fourteen hours a day, with no clocks and no electric light. Within a month, almost every subject reverted to two-shift sleep. The body remembers what the calendar forgot.