Tag Archives | William Dement

The 90-Minute Rule

“Human beings aren’t designed to expend energy continuously. Rather, we’re meant to pulse between spending and recovering energy.” – Tony Schwartz (source) In the late 1950’s, researchers William Dement and Nathaniel Kleitman documented that humans sleep in 90-minute cycles – from light to deep sleep and back to light sleep again. Professor Kleitman later discovered…

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