Astronomers theorizing the existence of small moons orbiting larger moons have proposed calling them “moonmoons.” The planet Kepler-1625b, which has a Neptune-sized moon distantly orbiting it, was cited as “sort of the best-case scenario for a moonmoon.”

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.

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.”

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.

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.”

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.

“Considering how seldom people think of looking for sunset at all, and how seldom, if they do, they are in a position from which it can be fully seen,” it’s rare to witness an excellent one, John Ruskin argued in 1843. Evelyn Waugh saw a radiant pink sunset behind a shadow-gray Mount Etna in 1929. “Nothing I have ever seen in Art or Nature,” he wrote, “was quite so revolting.”

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.