Nothing could seem more “natural” than our rhythms of sleep, yet there is a history of sleep. Historians have recognized various changes in sleeping patterns in the modern industrialized and post-industrial world, which have also been studied by scientists.

Over the past several decades historians are discovering and documenting earlier patterns of sleep in the medieval and early modern periods.

Historian Roger Ekirch (Virginia Tech University) has studied pre-industrial sleep patterns and has made some interesting discoveries. According to the BBC, “Ekirch had been researching a book about the history of night-time, and at the time he had been looking through records that spanned the era between the early Middle Ages and the Industrial Revolution. He was dreading writing the chapter on sleep, thinking that it was not only a universal necessity – but a biological constant. He was sceptical that he’d find anything new.”

Ekirch began to discover curious references to sleep in court records, literary sources, and other period documents. Many medieval and early modern people slept in two different blocs of sleep nightly, referred to in English as “first sleep” and “second sleep.” Ekirch has designated these patterns as segmented sleep patterns (or biphasic sleep).

The BBC explains that “Biphasic sleep was not unique to England, either – it was widely practised throughout the preindustrial world. In France, the initial sleep was the ‘premier somme‘; in Italy, it was ‘primo sonno‘. In fact, Eckirch found evidence of the habit in locations as distant as Africa, South and Southeast Asia, Australia, South America and the Middle East.”

Historian Craig Koslofsky (University of Illinois at Urbana-Champaign) has examined the history of the night in early modern Europe, focusing on the use of stage lighting and street lights to illuminate darkness in early modern cities. His study also explores distinctions between urban and rural experiences of lightness and darkness, which may help explain divergences in urban and rural sleep patterns even before the Industrial Revolution.

Sleep scientists have been conducting sleep experiments for decades, examining how clocks, electric lighting, and industrial work routines have significantly altered sleep patterns. Some of their recent findings suggest that segmented sleep patterns still exist in some areas of the world and that they can be encouraged by certain environmental factors.

The history of sleep in the medieval and early modern periods is informing the ways in which sleep scientists research sleep patterns today.

A. Roger Ekirch, The Great Sleep Transformation: How the Industrial Revolution Changed Our Nights (Amsterdam, 2021).

A. Roger Ekirch, “The Modernization of Western Sleep: Or, Does Insomnia Have a History?,” Past & Present 226 (February 2015): 149-192.

Craig Koslofsky, Evening’s Empire: A History of the Night in Early Modern Europe (Cambridge: Cambridge University Press, 2011).

A. Roger Ekirch, At Day’s Close: Night in Times Past (W.W. Norton, 2005).

The BBC reports on the history of segmented sleep patterns.