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.”

“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.”

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.”

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.

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.

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.

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.

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.

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.”