For millennia, people slept in two shifts – once in the evening, and once in the morning. This practice, known as 'biphasic sleep', was common until the Industrial Revolution. Historian Roger Ekirch discovered evidence of this habit while researching a book on the history of night-time at the Public Record Office in London in the early 1990s.
Ekirch found a 1699 court deposition from nine-year-old Jane Rowth, who described how she and her mother had 'awoken from their first sleep' before two men arrived at their home. Her mother was later murdered. Ekirch was struck by the casual reference to 'first sleep', implying a second sleep was normal.
Further research revealed numerous mentions of two sleeps in letters, diaries, medical texts, and literature, including Geoffrey Chaucer's The Canterbury Tales and William Baldwin's Beware the Cat. The practice involved waking for an hour or two in the middle of the night, often used for prayer, conversation, or even crime.
The habit disappeared with the advent of street lighting and the Industrial Revolution, which encouraged longer, uninterrupted sleep. Ekirch's work suggests that waking at night is not necessarily a disorder but a remnant of a historical sleep pattern.
