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.

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.”

In Japanese tradition, ghosts and spirits are more likely to appear at dusk or dawn than in the middle of the night. “In order for people to see them and be frightened by them,” wrote folklorist Kunio Yanagita, “emerging in the pitch-dark after even the plants have fallen asleep is, to say the least, just not good business practice.”

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.

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.”

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?”

“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.

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.”

“Darkness has come upon me,” a hymn in the Rig Veda laments. “O Dawn, banish it like a debt.” The morning light is here asked, suggested translator Wendy Doniger, to act as a collection agency—to “make good what darkness had incurred or ‘exact’ the darkness from night as one would exact money.”