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.”

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.”

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.

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.”

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.”

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.

When a boat of carousing European sailors on the Bosporus awoke the sleeping Sultan Selim III one night in 1790, the Ottoman leader issued an emergency order to his administration against night revelers: “Warn all ambassadors and Europeans never to perform this shameless act again. I will mercilessly kill whoever does it.”

“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.”

“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.