By Amit Harlev
Q: During what time period(s) were polyphasic schedules common, and where geographically? (or if they were used everywhere and at every point in history, when did they stop being common and where?)
Sleep is a universal necessity, but not a universal constant. It has varied tremendously over both time and space. Segmented, or biphasic, sleep was the dominant pattern of human slumber in the Western world and perhaps elsewhere from time immemorial to the modern age (late 19th century.)
Q: Did everyone sleep polyphasically or just some people? (Also was it specific to age group, social status, or other factor?)
In the Western world, the vast majority did, nor was this pattern subject to age or geography. The one exception consists of social elites (e.g. aristocrats) who could afford candles, did not need to awaken to go to work, and who delighted in lording this fact over their social subordinates by entertaining and dining late at night. And yet, their sleep was also segmented. It just operated according to a later timetable.
Q: What did people do during the hours of the night during which they were awake?
They spent this time in myriad ways, from the spiritual to the profane, in addition to more mundane tasks such as rising to urinate, either in a chamber pot or on mild evenings outdoors. Fires needed to be tended or perhaps a tub of ale brewed. Virgil in the Aeneid wrote of women servants, after the “first slumber,” who “ply the distaff by the winking light, and to their daily labor add the night.” The sick were given potions and elixirs; whereas for the poor, the dead of night (midnight to three a.m.) was a prime time for poaching and petty theft so long as the moon, or “tattler,” was not full. Orchards were pilfered and firewood filched. Still, most persons never left their beds, preferring instead to ponder dreams from which they awakened. No other period afforded such a secluded interval of darkness in which to absorb fresh visions of solace, spirituality, and self-revelation. There were also prayers to be recited ‘when you awake in the night.” And no time was thought better for sexual intimacy if a couple wished to conceive children. A sixteenth-century French physician ascribed the fecundity of rural peasants to early morning intercourse “after the first sleep” when, he claimed, they “have more enjoyment” and “do it better”.
Orchards were pilfered and firewood filched.
Q: What caused monophasic sleep to become prevalent?
Broadly put, the Industrial Revolution accentuated forces rooted in both technology and culture, that transformed segmented sleep. As with other forms of biological change, the transition was lengthy and erratic. Nighttime slumber that had been “segmented,” with a provenance as old as humankind, gradually, by the late nineteenth century, became compressed and consolidated throughout much of North America and Western Europe.
First, owing to a heightened sensitivity toward time, coupled with the growing importance of efficiency and productivity in daily life, sleep resembled, for many, a necessary evil best confined to a single interval – “stealing a march, so to speak, on the day and on one’s fellow human beings who are enjoying that second sleep,” as a London writer advised. Proponents of “early rising,” a very popular reform movement, urged parents to encourage children at an early age to arise after “their first sleep.” But even more decisive, was the growing prevalence of artificial illumination within homes and businesses as well as on public streets – first gas, followed in the late 1800s by electric lighting. As scientific research has shown, modern lighting can have a profound physiological effect upon sleep. Just a few hours of exposure can reset the circadian pacemaker controlling the flow of hormones and changes in body functions that have daily rhythms. Then, too, the dissemination of artificial lighting led to later bedtimes and sleep that was deeper, more compressed, and capable of being taken in a single interval. By the early twentieth century, if not earlier, most people exhibited an unquestioning adherence to seamless slumber.
Q: Any other interesting facts that you think are worth sharing?
A significant segment of the population in the United States and abroad [still] experience a biphasic pattern of sleep. Over ten per cent of Americans reportedly suffer from “middle-of- the-night” (MOTN) insomnia, the most common variety of sleeplessness whereby they have difficulty, not falling asleep, but waking up at night for up to an hour or more. To both their frustration and that of their physicians, there appears to be no explicable reason for their wakefulness. Many patients, I have been told, regard themselves as abnormal, which only heightens their anxiety, thereby accentuating their inability to sleep.
But there is strong historical evidence that many insomniacs may, in fact, be experiencing this older, more natural pattern of segmented slumber. Notably, middle-of-the-night insomnia was not a problem before the late 1800s. Medical texts as early as the sixteenth century regarded the interval of wakefulness separating first from second sleep as utterly normal and, hence, unworthy of discussion except for affording a preferred time for ingesting medicine, engaging in sex, and shifting from one side of the body to another to aid digestion. Fitful sleep, whether caused by sickness, bugs, or inclement weather, was not confused with wakefulness between first and second sleep. In fact, not until the turn of the nineteenth century and sleep’s consolidation, did physicians view nocturnal awakening as an illness requiring medication. What of individuals today, who awaken in the middle of the night while the rest of us sleep seamlessly? Some who are prone to nocturnal awakenings may possess circadian rhythms capable of withstanding the impact of artificial lighting, or are otherwise disposed to resist the transition to consolidation. Further, as David Neubauer at Johns Hopkins has speculated, consolidated sleep, as an artificial invention of modern life, may be inherently unstable and, thus, all the more vulnerable to disruption. It also stands to reason that the transition from segmented sleep, dominant in all likelihood since time immemorial, would take longer than just one or even two centuries to run its course.