Before the invention of artificial lighting and the rise of the modern 9-to-5 lifestyle, human sleep patterns were very different from what we consider “normal” today.
For thousands of years, people practiced what is known as biphasic or segmented sleep, sleeping in two distinct phases with a period of wakefulness in between.
This historical pattern was shaped by natural light cycles and daily routines that aligned with the setting and rising of the sun.
The transition to our current consolidated sleep model only began in recent centuries and was driven by major changes in technology, urban life, and social expectations.
The Pattern of Segmented Sleep
Segmented sleep involved two main sleep periods: the "first sleep" and the "second sleep." People would typically go to bed shortly after sunset, around 8 or 9 p.m., when the natural light faded and daily chores were done.
This first sleep lasted for roughly four hours. After this, individuals would naturally wake up sometime around midnight. This period of wakefulness, usually lasting an hour or more, was not seen as insomnia or a disruption, but rather as a normal, even productive, part of the night.
During this middle period, people would read, pray, meditate, tend to chores, or even visit neighbors. Diaries, medical texts, and literary works from the medieval and early modern periods frequently reference this time of “quiet wakefulness.”
It was a time for calm reflection, creativity, and sometimes intimacy. Afterward, people would return to bed for their “second sleep,” lasting another four hours or so until dawn.
Cultural and Historical Evidence
The idea of segmented sleep isn’t just a theory, it is well documented in historical records. References to “first sleep” and “second sleep” appear in documents from the 15th to the 19th century across Europe and beyond.
For example, in Chaucer’s “Canterbury Tales” or in the writings of Virgil and Homer, there are clear indications that nighttime was naturally divided.
Historical accounts show that this pattern was not limited to the wealthy or literate. Farmers, townspeople, and even clergy often organized their nights around two sleep sessions.
Medical texts from the era also recommended that people make use of the wakeful interval for contemplation or conversation, even suggesting that this time was particularly good for digestion and mental clarity.
The “Weird Habit” Actually Made Sense
Before electricity, people relied on natural light. The sun’s rising and setting largely determined the structure of daily life.
With no bright lights to keep people alert into the night, melatonin, the hormone that promotes sleep, was produced in sync with the darkening skies. It made sense to wind down early and let the body rest in phases, especially during the long winter nights.
This form of sleep might have even been more restorative. Some sleep researchers suggest that segmented sleep aligns more closely with our circadian rhythms, allowing the body to enter deep sleep more efficiently.
The period of quiet wakefulness in between offered a time to relax mentally without the distractions of the daytime world.
The Invention of Artificial Light
The shift away from segmented sleep began with the spread of artificial lighting, particularly gas lamps in the 18th century and later the electric bulb in the late 19th century.
These innovations extended the day and allowed people to work, socialize, and read well into the night.
No longer dependent on the sun, people began staying up later and eventually started going to bed in a single consolidated block of sleep.
The Industrial Revolution intensified this shift. Factory schedules demanded early rising and long, uninterrupted work hours. Urbanization further reinforced the new sleep norm.
Over time, the middle-of-the-night wakefulness came to be seen as a problem rather than a natural part of the sleep cycle. By the early 20th century, references to first and second sleep had all but disappeared from common language.
Modern Implications
Today, many people suffer from what they believe is insomnia when they wake up in the middle of the night. However, some researchers believe this could be a remnant of our old biphasic sleep pattern.
Sleep historian Roger Ekirch, who has written extensively on the topic, argues that understanding our historical sleep habits can help modern people make sense of their own patterns.
There’s even a growing interest in reclaiming segmented sleep. Some people find that waking naturally in the night and embracing that period, rather than fighting it, can lead to better rest and a deeper sense of calm.
With flexible work schedules and more awareness around sleep health, a return to a more natural rhythm might not be out of reach.
While our artificial lights and hectic lifestyles may have rewritten the rules of sleep, the memory of first and second sleep remains embedded in our biology. Perhaps it’s time to listen to what our bodies have been trying to tell us all along.
