Biphasic Sleep: How the Industrial Revolution Killed 2026

The disappearance of biphasic sleep—the habit of sleeping in two distinct blocks separated by a period of wakefulness—is a story of how the Industrial Revolution reshaped one of humanity's oldest daily routines. For centuries, people in pre-industrial Europe routinely experienced what historians call "first sleep" and "second sleep," with a quiet waking interval in between.

Today, waking in the middle of the night is often treated as a sleep disorder. But research by historian Roger Ekirch and psychiatrist Thomas Wehr suggests it may be a remnant of a deeply ingrained pattern that industrialization gradually erased.

What Was Biphasic Sleep?

Biphasic sleep refers to a sleep pattern split into two segments, usually with a period of wakefulness in between. According to Ekirch's research, this was common in medieval and early modern Europe, documented in fiction, legal records, and personal diaries.

Ekirch told the BBC that the first sleep phase might begin around 9 or 10 p.m. and last until roughly 11 p.m. or midnight. Then came a waking period of an hour or more, used for talking, praying, socializing, or even chores. After that, people returned to bed for a second sleep until dawn.

This pattern was not considered abnormal. It was simply how sleep was organized before artificial lighting and factory schedules redefined the day.

The Evidence Behind Segmented Sleep

Ekirch's work drew on a wide range of historical sources, including novels, court records, and medical texts. References to "first sleep" and "second sleep" appear repeatedly, suggesting the practice was widespread and understood.

Separately, psychiatrist Thomas Wehr conducted an experiment with 15 men placed in an environment with restricted light exposure. The participants gradually adopted a biphasic pattern, sleeping in two blocks with a waking period in between. This supported the idea that segmented sleep may be biologically natural under certain conditions.

Together, these findings challenge the modern assumption that uninterrupted eight-hour sleep is the only healthy norm.

How the Industrial Revolution Changed Sleep

The Industrial Revolution brought factories, rigid work schedules, and artificial lighting that extended the day. These changes made the flexible, two-part sleep pattern impractical for most people.

Workers needed to be on time for shifts, and employers demanded predictable availability. The gap between first and second sleep became a liability rather than a normal part of life. Over time, the ideal of consolidated sleep took hold.

As a result, waking at night gradually came to be seen as a problem—a sign of insomnia or poor health—rather than a natural rhythm.

Why This Matters Today

Many people still wake in the middle of the night and worry that something is wrong. Understanding the history of biphasic sleep can reduce that anxiety and offer a new perspective on sleep health.

Modern sleep science generally recommends uninterrupted sleep for optimal rest, but the historical view suggests that human sleep patterns are flexible. What matters most is total sleep duration and how rested you feel during the day. Context on how this played out before sits in Biphasic Sleep: How the Industrial Revolution Killed. A companion piece, Parenting Pressure: Experts Push Back on Impossible Standards, approaches the same subject from another angle.

• Biphasic sleep was common in pre-industrial Europe, with two sleep blocks and a waking interval.
• Historical evidence includes diaries, fiction, and legal documents referencing "first sleep" and "second sleep."
• The Industrial Revolution imposed rigid schedules and artificial light, making segmented sleep impractical.
• Thomas Wehr's experiment showed that restricted light can lead to biphasic sleep in modern participants.
• Waking at night may not be a disorder but a remnant of a natural pattern.

Comparing Sleep Patterns Across Eras

This table illustrates how cultural and economic forces shaped something as personal as sleep. The shift was not driven by biology but by changing social and industrial demands. The background to this story is set out in How the Slave Trade Fueled the Industrial Revolution. A related thread runs through Science: latest articles.

What to Watch Next

As sleep research continues, the history of biphasic sleep may inform new approaches to sleep health. Some researchers argue that understanding our past can help us design healthier sleep environments today. Earlier coverage in Spain Pension Fraud: Man Ordered to Repay €9,240 After Colombia Trips shows how the argument developed. A closer look at the same subject appears in Xiaomi Redmi Note 17 5G: Launch Price and Key Specs Revealed.

For anyone who wakes at night, the lesson is clear: it may not be a sign of failure. It could simply be a echo of a time when sleep was woven into the rhythm of daily life differently. Anyone following the wider picture can start with Xiaomi Redmi Buds 6 Pro Drop to €44.99 in Lavender Purple. The same theme surfaces in Jensen Huang Backs Trump on AI: 'We Won't Let That Happen', which takes a different angle.