An interview with Prof. Roger Ekirch, a historian at Virginia Polytechnic Institute and State University.

He graduated cum laude with highest distinction in history from Dartmouth College. 1972. Obtaining his M.A. and Ph.D. degrees from Johns Hopkins University, he arrived at Virginia Tech in 1977.

Is it true that we used to sleep in two phases: first sleep and second sleep?

Absolutely, the evidence for which is voluminous. Arguably from time immemorial to the nineteenth century, the dominant pattern of sleep in Western societies was biphasic, whereby most preindustrial households retired between 9 and 10pm, slept for 3 to 3 ½ hours during their “first sleep,” awakened after midnight for an hour or so, during which individuals did practically anything and everything imaginable before taking a “second sleep,” roughly until dawn.

How far back does the evidence extend for this biphasic pattern of sleep?

The earliest reference I have found is in Homer’s Odyssey, written in either the late eighth or early seventh century B.C. A much longer reference appears in Virgil’s Aeneid, nor were these the only classical writers to refer to this biphasic pattern of sleep - among others, Thucydides, Livy, and Apuleius.

When did it become commonplace to consolidate these two phases into a compressed single sleep and why did this change occur?

The transformation over the course of the nineteenth century in Europe and the United States was protracted and erratic for technological and cultural reasons, both a product in large measure of the Industrial Revolution.

Most important was the growing prevalence of artificial illumination, first gas, followed later by electric lighting. Not until the early twentieth century, with the lingering exception of remote rural areas, would seamless slumber be perceived as utterly normal. ...