Your Sleeping Brain and Circadian Rhythms

Our brain doesn’t work on Eastern Standard or Mountain Standard time, it has a clock all it’s own — the circadian clock or body clock, and the ticking of the clock is what is known as the circadian rhythms. The circadian rhythms are adjusted to the environment by external cues called zeitgebers, the primary one of which is daylight.

Our bodies are on a 24/7 cycle, where the activity level is highest at night and lowest during the day, according to how the melatonin is released (peaking at night and tapering off during the day). A distinct group of cells are located in the hypothalamus. These cells, called the suprachiasmatic nucleus (SCN) receive information about illumination through the eyes. Destruction of the SCN results in the complete absence of regular sleep-wake rhythm. In the absence of regular cues, like daylight or clocks, they try to maintain their regular rhythm and most are able to do it through artificial means, such as electric light.

Disruption to rhythms usually has a negative effect. Many travelers experience “jet lag” not because of time zone differences, but because they are tired and disoriented from the lack of sufficient oxygen and the inability to sleep soundly under the conditions of an airplane.

A number of other disorders exist that are associated with irregular circadian rhythms. Research has suggested that bipolar disorder may be one of them. Cardiovascular disease is another adverse health disorder, as well as the development of cancer, due to the suppression of melatonin production that is associated with the disruption of the circadian rhythm.

Sleep is required in order for the brain to repair connections that may have been disrupted during daytime hours. Lack of sleep affects moods, the ability to think and perform daily tasks, and the ability to act responsibly. Children who do not get enough sleep are cranky and have behavior problems. Adolescents fall asleep in class and are not able to concentrate enough to learn lessons.

An interesting study was conducted in 2006 at Germany’s University of Lubeck involving 13 medical students. The subjects were asked to remember the English translation of some German words immediately before going to sleep.   During the slow-wave stage oscillating currents to the foreheads were initiated on of some of the students. The next morning the students were asked to remember the words learned the previous day. Those who received the slight jot of currents remembered more than those who did not.

Even when we sleep our brains are still working, organizing our day and putting things that happened during the waking hours into our long-term memory. When you are at rest your brain is not. The first recorded brain activity, through the use of an electro encephalogram recording (EEG) of sleeping subjects, found the researchers amazed that the brain did not rest as they had thought, but worked at lower frequencies than during wake time. They called this “slow-wave sleep,” or “synchronized state,” because there seemed to be a pattern to the frequency.

After the subject is asleep initially it enters a light sleep phase for the first 90 minutes. Slowly seeping into a deeper sleep known as “desynchronized state,” or REM sleep (rapid eye movement). It is during this time most of our dreaming and memory consolidation occurs. We usually have 4-5 REM states a night, lasting approximately 90-120 minutes each. The first phase is shorter than the succeeding ones.

Through these slow and then “desynchronized” states of sleep our brain is able to burn memory — moving it from short-term to long-term. Without sleep our minds will not be able to hold memory — and then where would you be?

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About the author:

Ron White is a two-time U.S.A. Memory Champion and memory training expert. As a memory keynote speaker he travels the world to speak before large groups or small company seminars, demonstrating his memory skills and teaching others how to improve their memory, and how important a good memory is in all phases of your life. His CDs and memory products are also available online at



The Sleeping Brain (some in research) – Rolling Waves and Arctic Icecaps in the Sleeping Brain: Oscillation States Switch, by Chengyu Li, Ph.D

HealthiNation: Sleep Problems:

How Brain Works During Sleep:


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