By Dr. Mercola
'A growing body of evidence, garnered from both science and history, suggests the eight-hour sleep cycle may not be the most natural arrangement for humans after all.
One experiment conducted in the 1990s, for example, seemed to indicate that when completely left to their own devices, people would sleep for four hours, then wake for one or two hours before falling into a second four-hour sleep.
More recently, historians have uncovered a wealth of historical evidence that humans in fact used to sleep in two distinct segments.
Evidence includes diaries, court records, medical books and literature, in which these two sleep cycles are referred to in such a way as to make it clear that it was common knowledge at the time.'
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