A longtime practice of European peasants was to bring cows and sheep inside for the night. If one could ignore “the nastiness of their excrements,” a late seventeenth-century visitor to Ireland opined, “the sweetness of their breath” and “the pleasing noise they made in ruminating or chewing the cud” might lull a person to sleep. A visitor to the Hebrides noted, however, that while urine was regularly collected and discarded, the dung was removed only once a year.

A special committee of the U.S. House of Representatives asked Lewis W. Leeds, a ventilation engineer and prominent critic of the popular belief that night air is inherently harmful to humans, to assess air quality inside the Capitol in 1868. The resulting report concluded that the House Chamber “is really the foulest place in the whole building,” with vents “so choked up with tobacco spittal and sweepings of the floor as to render the air rising from them very disagreeable.”

Into the early modern period, the word bug referred to a phantom in the dark; a 1535 translation of the Bible made for Henry VIII came to be known as the Bug Bible for its rendering of Psalm 91:5 as “Thou shalt not nede to be afrayed of eny bugges by night.” The word was changed to terrors in later editions, but the original sense still colors the common bedtime warning against letting bedbugs bite.

“The difference between us is very marked,” wrote Frederick Douglass to Harriet Tubman in 1868. “Most that I have done and suffered in the service of our cause has been in public, and I have received much encouragement at every step of the way. You, on the other hand, have labored in a private way. I have wrought in the day—you in the night.”

Emily and Charlotte Brontë, insomniacs both, would walk together in circles around the dining room table until they were tired enough to sleep. When Emily died and Charlotte suffered alone, her insomnia worsened; she added to her route, often wandering down neighborhood streets and into the cemetery until daybreak.

Asked whether it was night or day that first emerged when the universe came into existence, sixth-century-bc Greek philosopher Thales of Miletus replied, “Night, earlier by a day.”

A study of sixty-two mammalian species found that animals around the world have shifted into more nocturnal lives. “Humans are now this ubiquitous, terrifying force on the planet,” said lead author Kaitlyn Gaynor, “and we are driving all the other mammals back into the night-time.” The Southeast Asian sun bear, formerly diurnal, now spends as much as 70 percent more time awake at night to avoid humans.

Neo-Confucian philosopher Fujiwara Seika visited a friend on the night of the Han mid-autumn festival in 1606. As the moon appeared, the men climbed onto the roof. “The guest felt in his heart the endlessness of space,” wrote Seika’s student Hayashi Razan, “but the host seemed not to notice this, so the guest also acted as if he had not either.” Drunk on wine just before dawn, the pair began asking questions of the moon. No answers came, Razan wrote: “What could the moon say?”

In September 1776, fearing illness from night air, John Adams asked Benjamin Franklin to close the window of their room in a New Jersey inn. “I believe you are not acquainted with my Theory of Colds,” Franklin responded, launching into “a harangue upon air and cold and respiration and perspiration” in favor of leaving windows open. “I was so much amused,” Adams wrote in his journal, “that I soon fell asleep and left him and his philosophy together.”

Setting grim tales during nighttime was critiqued as a cliché in 1594 by Thomas Nashe. “When any poet would describe a horrible tragical accident,” he wrote, “to add the more probability and credence unto it, he dismally begins to tell how it was dark night when it was done.”

Poet Edward Fairfax kept a 1621 account of his daughter Helen’s terrible nightmares, describing an incident in which she complained about a demonic white cat that “has been long upon me and drawn my breath.” The cat, she said, “has left in my mouth and throat so filthy a smell that it does poison me.”

In August 2018 data scientist David Bamman examined how authors recently interviewed in the New York Times’ By the Book column answered the question “What’s on your nightstand?” Women mentioned male and female authors almost equally; men mentioned male authors more than 79 percent of the time. “Don’t read in bed,” advised Fran Lebowitz. “It’s too stimulating. Watch TV instead. It’s boring.”

“You don’t need a brain to sleep” was a central takeaway for a team of biologists who found that Cassiopea, a genus of upside-down jelly­fish, display signs of sleep deprivation when disturbed by water pulses at twenty-minute intervals throughout the night.

Annoyed by a prohibition against nocturnal work in late medieval France—enacted because candles provided insufficient light for quality performance—employers complained to Louis XI that workers occupied themselves from “four or five o’clock until the next day with various games and dissipations, and hardly want to apply themselves to do well.” In the winter of 1467, they received permission to extend working hours to ten pm.

According to his nephew, Pliny the Elder liked to rise in the middle of the night and study by lamplight. “Admittedly, he fell asleep very easily,” Pliny the Younger wrote, “and would often doze and wake up again during his work.”