Tedium - Meet The Medieval Insomniacs 😴

Hey all, Ernie here with a piece from Fahad Sperinck, who is making his second appearance in the newsletter after writing a great piece on death metal and normalcy. Check out his latest below:

Today in Tedium: The days are darkening, the mercury dropping, and the pumpkins a-glowing; this weekend, the small hand goes back an hour. Most of us will devour that precious extra hour of sleep like a bear falling on a baby seal. (Okay, sure, there’s something else happening within the next week that might keep you up at night—but enough existential anxiety.) Just for tonight, allow yourself to savor the descending twilight and drop into a moodier state of mind. As you lie in bed this weekend, take a moment to reflect on how human sleep—your sleep—has been molded by modernity. Your great-grandfather, like most good postindustrial citizens, probably went to bed around 10pm and woke at 6am, but his great-grandfather almost certainly didn’t. Today’s Tedium dissects the rhythms of the dark. — Fahad @ Tedium

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Lovemaking was a common midnight pastime. ‘The Idle Prentice Returned from Sea and in a Garret with a Common Prostitute’, by William Hogarth, 1747 (via The Met)

How “segmented sleep” went out of style

Segmented sleep, as it is now called, is thought to be prehistoric in humans. The discontinuity between the sleep of modern humans and our closest animal relatives has long been a puzzle in biology; a biphasic sleeping pattern is more appropriate to mammals our size living in natural light settings. Chimpanzees are awake for about 20% of their sleep period, and biphasic patterns of activity are common to many other mammals, birds, and even insects. With our obvious penchant for monophasic sleep, then, for most of the last century, biologists have reluctantly concluded that humans are fundamentally different from other organisms. What else could explain that we, seemingly alone in the animal kingdom, consolidate sleep into one phase?

In other words, how did segmented sleep go from common practice to dusty footnote? A decline in popularity can be traced around the development of gas street lamps in the early nineteenth century. Subsequent development of the incandescent light bulb by Thomas Edison, that great American enemy of sleep, only compounded problems.

It began, as it always does, with the aristocracy. Robbed of the only cue they had to go to bed—the setting of the sun and the fading of the light—these raucous revelers stayed up later and later into the night, setting a trend which percolated to the lower rungs of society as lighting became more commonplace. An assault on our primordial rhythm has been in progress ever since. We hold the distinction of being the only animals that artificially expand our photoperiod—the period of time each day that an organism receives light. Humans have managed to engineer perpetual summer by using artificial light to extend our days to 16 hours, whatever the season, leading some scientists to wonder whether this constant illumination is shoehorning sleep into an unnaturally small window.

In the early 90s, one chronobiologist set out to investigate this hypothesis—namely, that artificial light was the proximate cause of the disappearance of segmented sleep. Thomas Wehr recreated premodern lighting conditions by exposing seven subjects to indoor and outdoor light for 10 hours a day—about the natural photoperiod in London or New York on Halloween—and confining them to total darkness for 14 hours. The experiment lasted for four weeks. For the first few days, the subjects slept for eleven hours a night, likely repaying a sleep deficit. But by the fourth week, they were getting eight hours in two separate blocks, in a pattern virtually identical to the preindustrial slumberer.

‘Scholar with a Globe’ by Gerrit Dou, c. 1650 (via TuttArt)

What’s more, the subjects had an uncommon cocktail of hormones in their midnight waking hours. Relatively low cortisol, and heightened prolactin production, gave rise to a calm wakefulness, prompting Wehr to remark that they were in an “altered state of consciousness not unlike meditation”. Jesse Barron, a journalist who fell into an accidental segmented sleeping pattern after a spell of insomnia in 2016, concurred. Ordinarily a neurotic New Yorker, for whom wakefulness and anxiety were synonymous, he instead found a hidden reserve of calm in the small hours. For a while, midnight Netflix binges ensued, but they were soon followed by the recovery of a lost habit of reading physical books.

Not everyone is convinced. Neuroscientist and doyen of sleep Matthew Walker argues that a true human biphasic sleep pattern consists of one long bout of nocturnal sleep with a mid-afternoon nap. Walker points to an impressive list of evidence—the afternoon nap coincides with a widely observed dip in alertness, for example. But sleep patterns develop over millennia; it seems plausible that they could, and should, be tied to latitude. The siesta cultures he cites all live on or below the Mediterranean Se, with at least two more hours of winter light than the Western Europeans who loved a broken night’s sleep. Why waste precious daylight napping when you are locked in eternal night—in eighteen hours of darkness?