We’ve become so obsessed with getting that 'perfect' eight-hour block of sleep that we’ve forgotten it’s actually a very recent invention; for most of human history, people slept in two distinct segments with a purposeful gap of wakefulness in the middle.
Create a lesson on the history of human sleep patterns from ancient times to today. Explain segmented sleep (‘first sleep’ and ‘second sleep’), siesta cultures, monophasic and polyphasic sleep. Include how artificial lighting and industrialization changed sleep habits, the psychological and biological benefits of each pattern, and compare which sleep style may work best for modern humans.








Segmented sleep, also known as biphasic sleep, was the historical norm before the Industrial Revolution. According to historian A. Roger Ekirch, people typically slept in two distinct periods known as first sleep and second sleep. Instead of one continuous eight-hour block, individuals would wake up in the middle of the night for a period of wakefulness to socialize, reflect, or perform light tasks before returning to bed for their second rest.
A. Roger Ekirch is a historian who spent years researching old diaries and medical texts to understand human sleep habits. He discovered that for most of human history, people did not sleep in one long stretch. His research highlights that the modern obsession with a single eight-hour block is a relatively recent invention, and that our ancestors naturally followed a rhythm of segmented sleep with a purposeful gap of wakefulness in between.
The Industrial Revolution marked a major shift in how humans perceive time and manage their biological clocks. Before this era, waking up at 2:00 a.m. was seen as a natural 'watch' rather than a medical problem. As society moved toward standardized work hours and artificial lighting, the traditional rhythm of first and second sleep was replaced by the modern expectation of a single, uninterrupted block of rest, leading many to view natural wakefulness as insomnia.
Creado por exalumnos de la Universidad de Columbia en San Francisco
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Creado por exalumnos de la Universidad de Columbia en San Francisco
