Why Sleeping Through The Night May Not Be ‘Natural’

It’s undeniable that we need proper sleep not only to maintain our physical and mental health but also to function in our everyday lives. We consider eight uninterrupted hours of rest the marker of a healthy lifestyle — but is that really all that constitutes “proper sleep”?

Some scientists and historians have argued that we may not be built to sleep through the night in one long stretch. According to the work of one influential historian, our ancestors experienced sleep in a very different way.

Roger Ekirch, a historian at Virginia Tech University and author of At Day’s Close: Night In Times Past, has found that before the Industrial Revolution, humans likely slept in two separate intervals each night, waking for a while in between.

Ekirch laid out this thesis in 2001, when he published a paper based on 16 years’ worth of research suggesting that people slept in two distinct chunks. Being awake for an in-between period during the night was “a part of life’s rhythms,” according to Ekirch.

He first began investigating this phenomenon when he noticed the use of the terms “first sleep” and “second sleep” in a number of historical documents, including diaries, medical records and court documents. These accounts led him to believe that what he termed “segmented sleep,” or biphasic sleep, was at one time a common part of everyday life.

“I began to keep coming across references to first sleep and second sleep,” Ekirch told The Huffington Post. “One thing I found surprising was that the references were very casual — they were said in such a way as to assume that everyone else knew what they were referring to. That told me that this was not something unique or an anomaly.”

First Sleep, Second Sleep

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