- London, 17th century. The criminal documents of the city archives collected a number of references to sleep, which referred to the “first dream” and the “second dream”, as well as the description of what was done in the intermediate period.
When American historian Roger Ekirch appropriated it, he decided to investigate the issue further and in 2001 Sleep We Have Lost: Pre-Industrial Slumber in the British Islands ("The dream we have lost: Pre-industrial lethargy in the British Isles”), published in The American Historical Review.
Ekirch explored other European archives, letters and publications of all kinds, concluding that in the Europe of the Modern Age the two-phase prevailed. Pre-industrial Europeans slept at dusk. After two or three hours of sleeping, they woke up to midnight. During this speech period, some remained in bed, praying, reflecting or maintaining sexual intercourse. Others got up and engaged in housework, or talked to neighbors. And, as criminal files have shown, there were also people who used to steal.
Industrialization and, in particular, artificial light led to the modification of natural sleep habits. Or, in other words, what industrialization imposed was allowed by artificial light.
This habit could come from the Middle Ages and originate in Christianity. In the sixth century the monk St. Benedict forced him to wake up for prayer at midnight and it could be thought that this Benedictine habit spread to the whole of society. But Ekirch reviewed the classical authors and found references to biphasic sleep in his writings of Homer, Tito Livio or Plutarco. He also says that today, in many isolated communities without artificial light, they still sleep twice.
This idea was endorsed by an experiment in the 1990s. Maryland (EE.UU. ), NIMH psychiatrist Thomas Wehr, established “prehistoric” sleep conditions for several subjects and, in a few weeks, all tended to a fragmented sleep.
Industrialization and, in particular, artificial light led to the modification of natural sleep habits. Or, rather, what was imposed by industrialization was allowed by artificial light. The industry demanded the rigor and synchronization of workers' schedules, monetizing the time.And besides producing at work, workers had to consume it on the street so that the machinery of the new system worked properly. In the middle of the 18th century, the first streetlights were installed in major European cities, illuminating the bad habit of a single dream.
More and more professionals say that biphasic sleep is healthier, but they are aware that in this post-industrial society it is impossible to return to natural sleep.