The practice of yobai, “night crawling,” was common in rural communities in medieval Japan, and continued into the twentieth century. A young man would visit a young woman’s house after dark, disguising his features with a cloth to avoid embarrassment should his advances be rejected. These premarital liaisons could become formal if a child were conceived.

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 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.

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.”

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.”

Psychologists at the University of California recognized a lack of sleep “as a social repellent” and its effect contagious: “People who come in contact with a sleep-deprived individual, even through a brief one-minute interaction, feel lonelier themselves as a result.”

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.”

“When the white man landed on the moon, my father cried,” a young Oklahoma Indian told psychologist Robert Coles in the 1970s. “He was sure Indians were crying up there, and trying to hide, and hoping that soon they’d go back to their earth, the white men.” The boy also spoke to his aunt. “The moon is yours to look at and talk to,” she told him, “so don’t worry.”

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?”