In the early 1990s, psychiatrist Thomas Wehr conducted an experiment in which a group of people were plunged into darkness for 14 hours every day for a month.
It took some time for their sleep to regulate but by the fourth week the subjects had settled into a very distinct sleeping pattern. They slept first for four hours, then woke for one or two hours before falling into a second four-hour sleep.
In 2001, historian Roger Ekirch of Virginia Tech published a seminal paper, drawn from 16 years of research, revealing a wealth of historical evidence that humans used to sleep in two distinct chunks.
His book unearths more than 500 references to a segmented sleeping pattern…(which) describe a first sleep which began about two hours after dusk, followed by waking period of one or two hours and then a second sleep.
“It’s not just the number of references – it is the way they refer to it, as if it was common knowledge,” Ekirch says.
Read on – The Myth of the 8-hour Sleep
“Don Quixote followed nature, and being satisfied with his first sleep, did not solicit more. As for Sancho, he never wanted a second, for the first lasted him from night to morning.” – Miguel Cervantes, Don Quixote (1615)