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The Forgotten Practice of Divided Sleep
For centuries, people across the globe slept in two distinct phases-once at dusk and again before dawn. Historians now reveal how this ancient habit faded with the rise of industrialization.
A Child's Testimony Unlocks a Mystery
In 1699, nine-year-old Jane Rowth of northern England awoke from her "first sleep" to find her mother preparing to leave their home. The visit was expected, but Jane's mother never returned-her murder unsolved. Decades later, historian Roger Ekirch stumbled upon Jane's court testimony, where the phrase "first sleep" leapt from the page. It was a clue to a vanished way of life.
Ekirch, a professor at Virginia Tech, had been researching nighttime history when he noticed the term appearing repeatedly in pre-industrial records. "She referred to it as utterly normal," he recalled. What began as a curiosity became a groundbreaking discovery: biphasic sleep-two separate sleep periods per night-was once universal.
Evidence Across Centuries and Continents
From medieval literature to colonial travelogues, references to divided sleep surfaced everywhere. Geoffrey Chaucer's The Canterbury Tales (1387-1400) and William Baldwin's Beware the Cat (1561) casually mentioned it. In France, it was called premier somme; in Italy, primo sonno. Records from Brazil to Oman described people rising after midnight to eat, socialize, or work.
The earliest mention dates to the 8th Century BC in Homer's The Odyssey, while the last traces vanish by the early 1900s. Ekirch found the practice in letters, diaries, medical texts, and even ballads, suggesting it was the default human sleep pattern for millennia.
How Biphasic Sleep Worked
In pre-industrial Europe, people typically retired between 21:00 and 23:00, sleeping for a few hours on straw-stuffed mattresses or bare earth. They awoke naturally around midnight for "the watch," a 1-3 hour period of wakefulness. Under moonlight or rush lights (waxed reeds), they tended fires, brewed beer, or visited neighbors. Criminals exploited the darkness, while couples used the time for intimacy.
Christians recited prayers during this interval, and philosophers like a 18th-century London tradesman invented devices to record midnight insights. Afterward, people returned to bed for a "morning sleep" until dawn. Communal sleeping-often with strangers-required strict etiquette to avoid awkwardness.
The Science Behind the Shift
In 1995, Ekirch discovered a 1990s study by sleep scientist Thomas Wehr that replicated biphasic sleep in a lab. Fifteen men deprived of artificial light for weeks began sleeping in two segments, separated by wakefulness. Their melatonin levels adjusted, proving the pattern was biologically ingrained.
Recent research in Madagascar's electricity-free villages confirmed the phenomenon persists where artificial light is absent. Participants exhibited the same midnight wakefulness, though a week of exposure to light didn't alter their patterns-suggesting longer adaptation is needed.
The Industrial Revolution's Role
The decline of biphasic sleep began with gas lighting in 19th-century London, followed by electric lights. As nights grew brighter, people stayed up later but still rose at dawn for work, compressing sleep into one block. Ekirch traced this shift decade by decade, noting how artificial light disrupted circadian rhythms.
By the 20th century, the two-sleep system had vanished. Modern attitudes toward sleep-valuing uninterrupted rest and early rising-emerged as byproducts of this change. Ekirch notes that today's insomnia sufferers often panic over midnight wakefulness, unaware it was once normal.
A Lost Rhythm, Not a Lost Benefit
While biphasic sleep may seem ideal, Ekirch cautions against romanticizing the past. "There's no going back," he says. Modern sleep, though unnatural in pattern, is safer and more comfortable-free from lice, cold, or the threat of violence.
Yet the discovery offers solace to those struggling with sleep disorders. "Learning this history lessens anxiety," Ekirch says. The two-sleep system reminds us that human biology is adaptable-and that what feels abnormal today may have been routine for our ancestors.
