Why Do We Sleep Under Blankets, Even on the Hottest Nights? (2017)

Summary

Originally, only the wealthy could afford bed coverings. Maria Morri/ CC BY-SA 2.0 Late July. New York City. A bedroom on the top floor of a four-story building in which I installed an air conditioner with several thousand too few BTUs. I barely know what a BTU is. The temperature that day reached into the upper 90s Fahrenheit, with humidity just short of actual water. The tiny weak air conditioner struggled to cool the room down while a few feet away I struggled to fall asleep. And yet I was unable to sleep without some sort of covering. In this case it was the barest edge of my lightest sheet, touching the smallest possible part of my torso. Why this compulsion to be covered, however minimally, in order to sleep? A Red Cross nurse change the sheets on a patient’s bed, 1917. National Archives/ 20802254 Blankets are common, but not universal, to humans during sleep, at least in the modern day. But historically, the effort involved in weaving large sheets put blankets at much too high a price point for most to afford. From the linen bedsheets of Egypt around 3500 B.C. to wool sheets during the Roman empire straight through to cotton in medieval Europe, bed coverings were for the wealthy. By the Early Modern period in Europe, which followed the Middle Ages, production had increased enough so that more middle-class people could afford bedding, though not easily. “The bed, throughout Western Europe at this time, was the most expensive item in the house,” says Roger Ekirch, a historian at Virginia Tech who has written extensively about sleep. “It was the first major item that a newly married couple, if they had the wherewithal, would invest in.” The bed and bedding could make up about a third of the total value of an entire household’s possessions, which explains why bedsheets frequently showed up in wills. A depiction of a 15th-century bed. Public Domain In place of blankets and sheets, other sources of heat were common at night, usually from multiple people sharing a b...