The need to sleep eight hours is the cause of much stress. But for centuries we happily woke up in the middle of the night
This week's BBC report on segmented sleep was only the latest in a stream of sleep-related news stories, but it was notable in that it was considerably more sensible than most – offering the reassuring fact that we have long slept not in one solid stretch but as a performance of two halves, with an interval.
This is not a new idea. For centuries we were accustomed to the idea of "first sleep" or "dead sleep" and "second sleep". It was accepted that between this first bout of slumber and the next there would lie an hour or so of quiet wakefulness, sometimes known as a "watch". This period was often used for prayer, or writing, or sex, or even for visiting the neighbours. But the idea of two sleeps dwindled in the late 17th century, so that by 1920 it was practically obsolete. For the last century or so we have been wedded to the idea of eight solid hours abed. And since the key to our sense of restedness often lies in our perception of how much sleep we have had, the figure of eight hours looms large.
Fraternally, Philip Carter / Facebook / Great is Truth and mighty above all things (I Esdras 4:41)
Cloistered monks and nuns adhere to a 10-century-old strict schedule with a common zeitgeber of a night split by a 2- to 3-h-long Office (Matins). The authors evaluated how the circadian core body temperature rhythm and sleep adapt in cloistered monks and nuns in two monasteries. Five monks and five nuns following the split-sleep night schedule for 5 to 46 yrs without interruption and 10 controls underwent interviews, sleep scales, and physical examination and produced a week-long sleep diary and actigraphy, plus 48-h recordings of core body temperature. The circadian rhythm of temperature was described by partial Fourier time-series analysis (with 12- and 24-h harmonics). The temperature peak and trough values and clock times did not differ between groups. However, the temperature rhythm was biphasic in monks and nuns, with an early decrease at 19:39 ± 4:30 h (median ± 95% interval), plateau or rise of temperature at 22:35 ± 00:23 h (while asleep) lasting 296 ± 39 min, followed by a second decrease after the Matins Office, and a classical morning rise. Although they required alarm clocks to wake-up for Matins at midnight, the body temperature rise anticipated the nocturnal awakening by 85 ± 15 min. Compared to the controls, the monks and nuns had an earlier sleep onset (20:05 ± 00:59 h vs. 00:00 ± 00:54 h, median ± 95% confidence interval, p= .0001) and offset (06:27 ± 0:22 h, vs. 07:37 ± 0:33 h, p= .0001), as well as a shorter sleep time (6.5 ± 0.6 vs. 7.6 ± 0.7 h, p= .05). They reported difficulties with sleep latency, sleep duration, and daytime function, and more frequent hypnagogic hallucinations. In contrast to their daytime silence, they experienced conversations (and occasionally prayers) in dreams. The biphasic temperature profile in monks and nuns suggests the human clock adapts to and even anticipates nocturnal awakenings. It resembles the biphasic sleep and rhythm of healthy volunteers transferred to a short (10-h) photoperiod and provides a living glance into the sleep pattern of medieval time.
Fraternally, Philip Carter / Facebook / Great is Truth and mighty above all things (I Esdras 4:41)
Economists and bureaucrats who ventured out into the [French] countryside after the Revolution were horrified to find that the work force disappeared between fall and spring. The fields were deserted from Flanders to Provence. Villages and even small towns were silent, with barely a column of smoke to reveal a human presence. As soon as the weather turned cold, people all over France shut themselves away and practiced the forgotten art of doing nothing at all for months on end.
In the mountains, the tradition of seasonal sloth was ancient and pervasive. “Seven months of winter, five months of hell,” they said in the Alps. When the “hell” of unremitting toil was over, the human beings settled in with their cows and pigs. They lowered their metabolic rate to prevent hunger from exhausting supplies. If someone died during the seven months of winter, the corpse was stored on the roof under a blanket of snow until spring thawed the ground, allowing a grave to be dug and a priest to reach the village.
The same mass dormancy was practiced in other chilly parts. In 1900, The British Medical Journal reported that peasants of the Pskov region in northwestern Russia “adopt the economical expedient” of spending one-half of the year in sleep: “At the first fall of snow the whole family gathers round the stove, lies down, ceases to wrestle with the problems of human existence, and quietly goes to sleep. Once a day every one wakes up to eat a piece of hard bread. ... The members of the family take it in turn to watch and keep the fire alight. After six months of this reposeful existence the family wakes up, shakes itself” and “goes out to see if the grass is growing.”
It is unlikely this was hibernation in the zoological sense. While extreme cold might have set off a biological response normally seen only in squirrels, bears and marmots, human hibernation probably reflects a sensible, communal decision to stay in bed for as long as possible.
But the French seem to have been particularly sleepy. They “hibernated” even in temperate zones. In Burgundy, after the wine harvest, the workers burned the vine stocks, repaired their tools and left the land to the wolves. A civil servant who investigated the region’s economic activity in 1844 found that he was almost the only living presence in the landscape: “These vigorous men will now spend their days in bed, packing their bodies tightly together in order to stay warm and to eat less food. They weaken themselves deliberately.”
Fraternally, Philip Carter / Facebook / Great is Truth and mighty above all things (I Esdras 4:41)