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The Circadian Rhythms

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Each day, when the sun rises and sets, mammals and plants alike conform together with a celestial rhythm that instructs the activities of the day. The human body, along with nearly all other mammals, endogenously oscillates on a rhythm that coincides with these daily activities. However, when mammals are placed in an environment void of nearly all outside influences, also known as zeitgebers, these rhythms continue to run at specified intervals. Thus, the endogenous rhythm must be governed by an internal “master clock.” This master clock has been discovered to be the suprachiasmatic nuclei which are located in the anterior portion of the hypothalamus. Circadian rhythms are endogenous rhythms that mammals and plants exhibit. The term “circadian” was established in the 1950’s and is derived from the Latin prefix circa- which means “approximately,” and dies- which means “day.” (2) Nearly all living things have circadian rhythms that approximate to a 24 hour cycle; however there are some differences in lengths varying from species to species. (1) Numerous physiological processes are governed by the circadian rhythm, and by effect nearly every process in the body can be contributed to a rhythm of circadian fashion. The master clock of the circadian rhythm for biological processes is the suprachiasmatic nuclei, or SCN. (1)(2) The SCN is located in the anterior portion of the hypothalamus, posterior to and slightly inferior to the frontal lobe of the brain. The SCN is believed
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