Continuous sleep isn’t our only natural pattern.
Highlights:
- Waking up at night may be more natural than we think. Some preindustrial societies followed a “first sleep” and “second sleep” pattern.
- Long, dark nights may have encouraged people to sleep in two periods. Less artificial light shaped sleep.
- Modern research supports the idea that darkness can influence sleep patterns, including a shift toward more segmented sleep.
- Bright screens and artificial light can interfere with sleep and may be associated with health risks.
- Don’t panic if you wake up. Anxiety about not sleeping can make it harder to fall back asleep. Frequent awakenings or persistent daytime fatigue, however, are worth discussing with a healthcare professional.
If it hasn’t happened to all of us, it has happened to many of us, waking up around one or two in the morning. In the middle of the night, in complete darkness and silence. Those nights when you lie awake for hours and try counting sheep, only to make the terrible mistake of checking your phone, after which you can’t fall back asleep.
For much of human history, waking up in the middle of the night was not considered a disorder. According to historical evidence, it was a known sleep pattern in some preindustrial societies. Some people may think there is something wrong with them when they wake up in the middle of the night, says Roger Ekirch, a renowned American historian who has extensively researched sleep practices in preindustrial Europe.
In the mid-1980s, he got the idea to write a book and spent nearly two decades researching preindustrial life for what would eventually become At Day’s Close: Night in Times Past, published in 2005. His research initially focused on what nighttime life was like in Western Europe before the Industrial Revolution. He wanted to discover what customs and ways of living had developed around the night during that period.
“I assumed, as most people do, that the typical sleep pattern consisted of six or eight hours of uninterrupted rest,” he explains. He began by reviewing depositions in London archives, a source that could offer clues about the daily lives of ordinary people. Although the crime itself might have been irrelevant, a witness statement could tell him, for example, what someone was doing while awake at 10 p.m. and why.
It intrigued me enough to start looking into other sources.
Roger Ekirch
A statement from the late seventeenth century in northern England mentioned the expression “first sleep,” and that caught his attention. He initially thought it was an exception, something unusual, and did not necessarily assume that if there was a first sleep, there had to be a second one. “It intrigued me enough to start looking into other sources,” he says. That was when he began encountering the term “period between sleeps.”
In the 1990s, he began using databases to search through all kinds of literature, from plays to novels and poetry. “I was astonished by how frequently this terminology appeared and how familiar it seemed when people used it, as though it were completely ordinary, as though everyone knew what they were talking about,” he recalls. He translated the term “first sleep” into several languages and found more references, including one in Don Quixote. “Don Quixote fulfilled nature’s course by sleeping his first sleep, without allowing for the second, quite unlike Sancho, who never had a second, because his sleep lasted from night until morning, revealing his good constitution and few cares,” Miguel de Cervantes wrote in his novel.
In fact, there were special prayers to be said upon waking during the night.
Roger Ekirch
According to Ekirch’s reconstruction, the first sleep could begin at nightfall and last several hours. Some people would then remain awake for a period before going back to sleep until dawn. During that interval, they might do simple tasks that required very little light, such as peeling dried fruit. They might even visit with neighbors, making use of whatever rudimentary lighting they could afford. Many people, however, simply stayed in bed and prayed before eventually falling into a second sleep of similar length and waking for good at dawn. “In fact, there were special prayers to be said upon waking during the night,” Ekirch says.
For a long time, it has been assumed that sleeping continuously throughout the night is the natural way humans sleep. However, sleep patterns have varied across societies and historical periods, and even according to a person’s age. The available evidence does not allow us to reduce this variation to a single “natural” sleep pattern. One important difference between preindustrial nights and our own, however, was the much more limited availability of artificial light. Social, cultural, seasonal, and environmental factors also played a role.
After I described my historical research to him, we were equally excited.
Roger Ekirch
“I was browsing the internet looking for articles,” Ekirch recalls, when he came across a 1990s experiment by Dr. Thomas Wehr, published in the Journal of Sleep Research. In the study, healthy adults first followed a lighting schedule similar to that of modern life and were then exposed for several weeks to days with fewer hours of light and prolonged periods of darkness. When they had more time in darkness, participants were more likely to distribute their sleep across two periods, with an interval of wakefulness in between. “After I described my historical research to him, we were equally excited,” Ekirch recalls. Wehr’s experiment suggests that prolonged exposure to darkness can alter the organization of sleep and favor a more segmented pattern.
That said, sleep quality does not depend solely on whether sleep is continuous or divided into phases. It also depends on duration, depth, regularity, and, more broadly, whether sleep provides adequate recovery. There is also evidence that exposure to light at night may be associated with sleep disturbances and health effects. A preliminary study by researchers at Massachusetts General Hospital that followed adults found that those exposed to more artificial light at night had a higher risk of developing cardiovascular disease over the following five to ten years. In other words, greater exposure to nighttime light was associated with greater risk.
That is what makes these historical and scientific findings so interesting. Certainly not because we should reorganize our lives around natural light, but because they give us another reason to try to avoid bright light, such as the light from screens, during the last hour or two before bed and if we wake up in the middle of the night.
If this happens to you, try not to turn it into a catastrophe that creates anxiety and becomes a vicious cycle. Worrying that you are not going to get enough sleep can itself trigger a stress response, making it even harder to fall back asleep. One way to take some of the pressure off is to remember that waking up during the night is relatively common, even among people today.
What you should avoid is assuming that every nighttime awakening is simply a remnant of how our ancestors slept. If you wake up very frequently, cannot get back to sleep, or experience persistent daytime fatigue, it is worth talking to a healthcare professional to rule out conditions such as sleep apnea or other sleep disorders.
