The existence of a Basic Rest - Activity Cycle, or BRAC, during both sleep and wakefulness was proposed by Nathaniel Kleitman.
It is a human biological cycle of approximately 90 minutes (80–120 minutes) that is characterized by different level of excitement and rest. The cycle is controlled by the human biological clock. It is best observed in stages of sleep, for example, REM and the delta activity cycle.
Famous quotes containing the words basic, rest, activity and/or cycle:
“Good shot, bad luck and hell are the five basic words to be used in a game of tennis, though these, of course, can be slightly amplified.”
—Virginia Graham (b. 1912)
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“I see advertisements for active young men, as if activity were the whole of a young mans capital. Yet I have been surprised when one has with confidence proposed to me, a grown man, to embark in some enterprise of his, as if I had absolutely nothing to do, my life having been a complete failure hitherto. What a doubtful compliment this to pay me!”
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