InstaSleep Reviews Team article notes:

• For much of recorded history, humans have actually slept eight hours, but in two distinct phases of approximately four hours each. As scholar Roger Ekirch uncovered through his exhaustive historical study of literature, art, and diaries.

•  The “biphasic sleep” pattern, which was governed by the natural timing of nightfall and sunrise, didn’t last in the modern era. As artificially illuminating the night sky became more affordable, life—and soon sleep habits—changed.

http://www.history.com/news/why-do-humans-sleep-in-8-hour-cycles-biphasic-facts

This article was selected by the InstaSleep Reviews Team. Please enjoy this read and learn about why humans sleep in 8-hour cycles, and what history has to say about the way our sleep patterns have changed through the ages.