Most of us tend to think of waking up in the middle of the night as an inconvenience at best. Lying awake at two or three in the morning never feels great, especially if you have an early morning the next day.
Yet it turns out that in medieval times — and most likely long before that — people around the world may have slept in two shifts, naturally waking up for a few hours in the middle of each night before retiring once again. For most of human history, at least before electricity altered our circadian rhythms, this manner of sleeping may even have been the default way we spent our nights.
The idea that people may have slept in two sessions was first proposed by historian Roger Ekirch, after he read a 17th-century court record that mentioned, in an intriguingly casual way, a "first sleep." The offhand way these words were used sparked Ekirch's curiosity, and he began seeking out additional mentions of two-part sleeps. He found them.
Mentions of first and second sleeps appeared in The Canterbury Tales and in Beware the Cat. Such mentions also appeared in songs, medical texts, articles, and more, and extended far beyond England's borders and far earlier than medieval times.
Reportedly, people may have slept in two sessions in Africa, South America, the Middle East, and many other regions. Ekirch also found references to biphasic sleep in ancient texts by the Greek philosopher Plutarch, the Roman historian Livy, and other major historical figures.
According to Ekirch's theory, people's first sleep would typically last from around 9 to 11 P.M. They would then rise and remain awake until around 1 or 2 A.M. This moonlit time was used in many different ways. Sometimes, it served as an excuse to get extra chores done. People also used this time for prayer or philosophical reflection. Sometimes, they simply stayed in bed and talked.
In general, this seemed to be a time for connection and reflection. Ekirch wrote that many people who remained in bed "reflected on the dreams that typically preceded waking from their 'first sleep.' Not only were these visions unusually vivid, but their images would have intruded far less on conscious thought had sleepers not stirred until dawn."
Things seemingly shifted with the rise of artificial lighting, which enabled people to stay up later and also suppressed melatonin, leading to later sleep times. Intriguingly, in some studies where people have attempted to sleep without clocks or artificial lighting over the course of several weeks, they have often naturally begun to sleep in two segments once again.
So the next time you wake up in the middle of the night, instead of panicking or staring at the ceiling, you might take the opportunity to reflect on your ancient ancestors, who may have done just the same thing — and for whom a few hours of wakefulness around midnight was a part of life as valuable as any other.