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)
“We must remember the past, define the future, and challenge the present—wherever and however we can. It will take the rest of our lives even to begin. But then, what else have we to do?”
—Jane O’Reilly, U.S. feminist and humorist. The Girl I Left Behind, Introduction (1980)
“I see advertisements for active young men, as if activity were the whole of a young man’s 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!”
—Henry David Thoreau (1817–1862)
“The cycle of the machine is now coming to an end. Man has learned much in the hard discipline and the shrewd, unflinching grasp of practical possibilities that the machine has provided in the last three centuries: but we can no more continue to live in the world of the machine than we could live successfully on the barren surface of the moon.”
—Lewis Mumford (1895–1990)