To install click the Add extension button. That's it.

The source code for the WIKI 2 extension is being checked by specialists of the Mozilla Foundation, Google, and Apple. You could also do it yourself at any point in time.

Kelly Slayton
Congratulations on this excellent venture… what a great idea!
Alexander Grigorievskiy
I use WIKI 2 every day and almost forgot how the original Wikipedia looks like.
Live Statistics
English Articles
Improved in 24 Hours
Added in 24 Hours
Show all languages
What we do. Every page goes through several hundred of perfecting techniques; in live mode. Quite the same Wikipedia. Just better.

Basic rest–activity cycle

From Wikipedia, the free encyclopedia

The basic rest–activity cycle (BRAC) is a physiological arousal mechanism in humans proposed by Nathaniel Kleitman,[1] hypothesized to occur during both sleep and wakefulness.

Empirically, it is an ultradian rhythm of approximately 90 minutes (80–120 minutes[2]) that is characterized by different level of excitement and rest. The cycle is mediated by the human biological clock. It is most readily observed in stages of sleep, for example, rapid eye movement sleep (REM) and the delta activity cycle.

When awake, our brainwaves are faster during the first half of the cycle, when we feel alert and focused, and then our brainwaves slow; in the last 20 minutes when we feel dreamy and perhaps a little tired, while our body is being readied for the alert part of the following cycle.

When asleep, our brainwaves first slow and then rise, and the BRAC occurs as stages of sleep—first falling into deep sleep, then rising into the REM stage, when dreams occur.[3]


  1. ^ Kleitman, N., Sleep and Wakefulness, 1963, Reprint 1987: ISBN 9780226440736
  2. ^ Kleitman, N., Basic rest-activity cycle—22 years later, Journal of Sleep Research & Sleep Medicine, Vol 5(4), Dec 1982, 311–317
  3. ^ "Basic Rest and Activity Cycles," Polyphasic Society

This page was last edited on 4 September 2018, at 07:30
Basis of this page is in Wikipedia. Text is available under the CC BY-SA 3.0 Unported License. Non-text media are available under their specified licenses. Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc. WIKI 2 is an independent company and has no affiliation with Wikimedia Foundation.