WE SEEM TO REGARD seven to eight hours of unbroken sleep as our birthright. Anything less means that something is awry. And people are willing to try anything to achieve that solid slug of slumber. Like a new-millennium version of Goldilocks, they try firm beds, pillow-topped mattresses and all manner of sleep systems to find one that is “just right.” They shun caffeine and change their diet—porridge and warm milk, anyone? They visit sleep clinics and swallow some $3 billion worth of sleeping pills every year.
Yet a recent discovery and a reexamination of some classic sleep literature suggest that for some people the perfect eight hours of sleep remains elusive for a very simple reason: our need for such uninterrupted slumber may be nothing but a fairy tale.
The source of this new assault on conventional thinking comes not from a drug company lab or a university research program but from a historian. In his 2005 book At Day’s Close: Night in Times Past, A. Roger Ekirch, professor of history at Virginia Polytechnic Institute and State University, reveals that in preindustrial times, before gaslights and electricity were widely used, people typically slept in two bouts they called first sleep and second sleep. Back then, sleep was closely tied to natural light. Within an hour or so after sunset, people retired to bed, slept for about four hours and then woke up. They remained awake for a couple of hours and then at about 2 A.M. returned to sleep for roughly another four hours.
From before the first century on, the period between first and second sleep afforded a chance for quiet contemplation or—if you had company—sexual intimacy. But people also got out of bed and did household chores or visited with family and friends. “They did anything and everything,” Ekirch says. Of course, this pattern of sleep is no longer the norm in developed countries, where artificial light extends the workday. But anthropologists still observe a similar pattern of segmented sleep in some contemporary African tribes.
Snoozing Science Surprise
This history of broken sleep had been long forgotten until unearthed by Ekirch’s recent detective work. Quite independently, however, sleep research has suggested that breaking a night’s rest in two may result in a pattern more in tune with our inherent circadian rhythms and the natural environment. In the early 1990s Thomas A. Wehr, then a sleep researcher at the National Institute of Mental Health (NIMH), and his colleagues reported that when eight healthy men had their schedules shifted from their customary 16 hours of light and eight hours of dark to one in which they were exposed to natural and artificial light for 10 hours a day and confined to a dark room for 14 hours each night (similar to the natural durations of day and night in winter), they developed a sleep pattern characterized by two four-hour bouts, separated by one to three hours of quiet wakefulness. Thus, when freed from the time constraints on night imposed by modern life, subjects reverted to the segmented sleep of earlier times.
This sleep pattern is deeply embedded in mammalian evolution. Many animals that are active during the day—chimpanzees, chipmunks and giraffes among them—sleep at night in two distinct periods. In fact, Wehr points out that modern humans may be unique among animals in the extent to which their sleep is consolidated.
Wehr, now a scientist emeritus at the NIMH, thinks that the current common pattern of an uninterrupted seven or eight hours of sleep may be an artifact driven by chronic sleep deprivation. For example, when the subjects of his experiments were adapted to their customary eight-hour night, they fell asleep in just 15 minutes, suggesting they were exhausted. And no wonder. They slept for an average of only 7.2 hours. But when their schedules were switched to 14 hours of darkness, at first they slept for about 11 hours, as if they were catching up on many lost naps. Finally, their average amount of sleep settled to 8.9 hours (although it was divided into two). They also fell asleep much more gradually, taking about two hours.
The insights from Ekirch and Wehr have significant implications for both the understanding of sleep and sleeping problems. “Waking up after a couple of hours may not be insomnia,” Wehr says. “It may be normal sleep.” But sleep specialists are mostly unaware of these findings and have not yet incorporated them into clinical practice. One reason is that these discoveries have not been widely disseminated. Although Ekirch’s book received positive reviews, it is about history and not at the top of most reading lists. And whereas Wehr’s research is well known to sleep specialists, it is usually viewed in the context of mechanisms governing sleep.
It also does not help that these findings fly in the face of current thinking. Todd Arnedt, a sleep researcher and clinician at the University of Michigan at Ann Arbor, says that for patients who cannot maintain sleep he follows the conventional approach of attempting to consolidate their sleep. He did not know about the two bouts of sleep discovered by Ekirch and Wehr but in light of that phenomenon thinks that the conventional approach might not always be the best one. He points out that how patients perceive their sleep determines to some extent how well they sleep. He already tries to get his patients with insomnia to “stop seeing their sleep as problematic.” Ekirch notes that since he wrote his book many people have contacted him to tell him “how relieved they are to hear that their sleeping problem is natural.”
Arnedt speculates that if patients were told that interrupted sleep was normal, they might be less distressed and fall back to sleep more easily. Mary Carskadon, a sleep researcher at Brown University, agrees. She also did not know of Ekirch’s historical findings but did know of the segmented sleep pattern discovered by Wehr and that some animals take two sleeps. Considering these observations, she wonders if the archaic sleep pattern had some functional purpose. The change in sleep pattern “highlights something humanity might have lost in the hurly-burly times we live in today,” she observes.
Perchance to Dream
So did the interval between bouts of sleep, common in earlier times, actually provide something of value, or did our ancestors merely tolerate it? Ekirch believes that the period of quiet wakefulness did offer a unique opportunity to contemplate dreams—and thus gain access to an otherwise less accessible part of mental life. He points out that people in that era took their dreams more seriously than we do today. Dreams were thought to “predict the future, offer a mirror to one’s soul and reveal relations with God.” And dreams influenced people’s waking lives. “A dream prompted Virginian colonist John Rolfe to marry Pocahontas,” Ekirch offers as one example. Dreams were more likely to be recalled after the first bout of sleep than in the morning when they tend to “evaporate more quickly.” Wehr’s research backs up this idea. His subjects usually woke from their first sleep during a rapid eye movement (or REM) period, when dreaming is most likely.
But Carskadon points out that civilization as we know it is unlikely to return to those simpler times. “It’s hard to adapt to two bouts of sleep when you have to be at work at 8 A.M.,” she says.
Still, if you find yourself awake in the middle of the night, it is comforting to know that you are not abnormal or alone. You’re in the company of giraffes and chipmunks, of your ancestors and some of your contemporaries. If the usual measures don’t suffice to bring on solid sleep, you can choose instead to savor your hours of sleeplessness. It’s a time to meditate, have sex, think about dreams. Or, as Wehr says, you can “just lie there and go back to sleep.”
WE SEEM TO REGARD seven to eight hours of unbroken sleep as our birthright. Anything less means that something is awry. And people are willing to try anything to achieve that solid slug of slumber. Like a new-millennium version of Goldilocks, they try firm beds, pillow-topped mattresses and all manner of sleep systems to find one that is “just right.” They shun caffeine and change their diet—porridge and warm milk, anyone? They visit sleep clinics and swallow some $3 billion worth of sleeping pills every year.
Yet a recent discovery and a reexamination of some classic sleep literature suggest that for some people the perfect eight hours of sleep remains elusive for a very simple reason: our need for such uninterrupted slumber may be nothing but a fairy tale.
The source of this new assault on conventional thinking comes not from a drug company lab or a university research program but from a historian. In his 2005 book At Day’s Close: Night in Times Past, A. Roger Ekirch, professor of history at Virginia Polytechnic Institute and State University, reveals that in preindustrial times, before gaslights and electricity were widely used, people typically slept in two bouts they called first sleep and second sleep. Back then, sleep was closely tied to natural light. Within an hour or so after sunset, people retired to bed, slept for about four hours and then woke up. They remained awake for a couple of hours and then at about 2 A.M. returned to sleep for roughly another four hours.
From before the first century on, the period between first and second sleep afforded a chance for quiet contemplation or—if you had company—sexual intimacy. But people also got out of bed and did household chores or visited with family and friends. “They did anything and everything,” Ekirch says. Of course, this pattern of sleep is no longer the norm in developed countries, where artificial light extends the workday. But anthropologists still observe a similar pattern of segmented sleep in some contemporary African tribes.
Snoozing Science Surprise
This history of broken sleep had been long forgotten until unearthed by Ekirch’s recent detective work. Quite independently, however, sleep research has suggested that breaking a night’s rest in two may result in a pattern more in tune with our inherent circadian rhythms and the natural environment. In the early 1990s Thomas A. Wehr, then a sleep researcher at the National Institute of Mental Health (NIMH), and his colleagues reported that when eight healthy men had their schedules shifted from their customary 16 hours of light and eight hours of dark to one in which they were exposed to natural and artificial light for 10 hours a day and confined to a dark room for 14 hours each night (similar to the natural durations of day and night in winter), they developed a sleep pattern characterized by two four-hour bouts, separated by one to three hours of quiet wakefulness. Thus, when freed from the time constraints on night imposed by modern life, subjects reverted to the segmented sleep of earlier times.
This sleep pattern is deeply embedded in mammalian evolution. Many animals that are active during the day—chimpanzees, chipmunks and giraffes among them—sleep at night in two distinct periods. In fact, Wehr points out that modern humans may be unique among animals in the extent to which their sleep is consolidated.
Wehr, now a scientist emeritus at the NIMH, thinks that the current common pattern of an uninterrupted seven or eight hours of sleep may be an artifact driven by chronic sleep deprivation. For example, when the subjects of his experiments were adapted to their customary eight-hour night, they fell asleep in just 15 minutes, suggesting they were exhausted. And no wonder. They slept for an average of only 7.2 hours. But when their schedules were switched to 14 hours of darkness, at first they slept for about 11 hours, as if they were catching up on many lost naps. Finally, their average amount of sleep settled to 8.9 hours (although it was divided into two). They also fell asleep much more gradually, taking about two hours.
The insights from Ekirch and Wehr have significant implications for both the understanding of sleep and sleeping problems. “Waking up after a couple of hours may not be insomnia,” Wehr says. “It may be normal sleep.” But sleep specialists are mostly unaware of these findings and have not yet incorporated them into clinical practice. One reason is that these discoveries have not been widely disseminated. Although Ekirch’s book received positive reviews, it is about history and not at the top of most reading lists. And whereas Wehr’s research is well known to sleep specialists, it is usually viewed in the context of mechanisms governing sleep.
It also does not help that these findings fly in the face of current thinking. Todd Arnedt, a sleep researcher and clinician at the University of Michigan at Ann Arbor, says that for patients who cannot maintain sleep he follows the conventional approach of attempting to consolidate their sleep. He did not know about the two bouts of sleep discovered by Ekirch and Wehr but in light of that phenomenon thinks that the conventional approach might not always be the best one. He points out that how patients perceive their sleep determines to some extent how well they sleep. He already tries to get his patients with insomnia to “stop seeing their sleep as problematic.” Ekirch notes that since he wrote his book many people have contacted him to tell him “how relieved they are to hear that their sleeping problem is natural.”
Arnedt speculates that if patients were told that interrupted sleep was normal, they might be less distressed and fall back to sleep more easily. Mary Carskadon, a sleep researcher at Brown University, agrees. She also did not know of Ekirch’s historical findings but did know of the segmented sleep pattern discovered by Wehr and that some animals take two sleeps. Considering these observations, she wonders if the archaic sleep pattern had some functional purpose. The change in sleep pattern “highlights something humanity might have lost in the hurly-burly times we live in today,” she observes.
Perchance to Dream
So did the interval between bouts of sleep, common in earlier times, actually provide something of value, or did our ancestors merely tolerate it? Ekirch believes that the period of quiet wakefulness did offer a unique opportunity to contemplate dreams—and thus gain access to an otherwise less accessible part of mental life. He points out that people in that era took their dreams more seriously than we do today. Dreams were thought to “predict the future, offer a mirror to one’s soul and reveal relations with God.” And dreams influenced people’s waking lives. “A dream prompted Virginian colonist John Rolfe to marry Pocahontas,” Ekirch offers as one example. Dreams were more likely to be recalled after the first bout of sleep than in the morning when they tend to “evaporate more quickly.” Wehr’s research backs up this idea. His subjects usually woke from their first sleep during a rapid eye movement (or REM) period, when dreaming is most likely.
But Carskadon points out that civilization as we know it is unlikely to return to those simpler times. “It’s hard to adapt to two bouts of sleep when you have to be at work at 8 A.M.,” she says.
Still, if you find yourself awake in the middle of the night, it is comforting to know that you are not abnormal or alone. You’re in the company of giraffes and chipmunks, of your ancestors and some of your contemporaries. If the usual measures don’t suffice to bring on solid sleep, you can choose instead to savor your hours of sleeplessness. It’s a time to meditate, have sex, think about dreams. Or, as Wehr says, you can “just lie there and go back to sleep.”
