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Inner body clocks: understanding the science of chronobiology.

The human body has daily rhythms that seem to be governed by what scientists now regard as a "biological clock." Heart rate, respiration rate, blood pressure, body temperature, and urine excretion all have varying levels (peaks during the day and troughs that occur at night). Such functions are also known as "circadian rhythms."

Although environmental clues sometimes influence these rhythms, such as the light and dark cycles, many rhythms persist when environmental clues are removed.

In experiments designed to understand the workings of the body's inner clocks, people were observed as they lived for weeks with neither social nor geophysical cues, such as set meal times and light-dark cycles. The basic rhythms continued.

The most well-known circadian rhythm is that of body temperature, which varies daily only a degree or two in a healthy person, peaking in late afternoon and dropping during early morning hours.

The temperature rhythm persists when the individual does not follow daily routine, such as periods when one is confined to bed for 24 hours, or when meal time is varied, or when no food is eaten during fast periods.

Levels of blood sugar, essential to body fuel, start decreasing about noon. By 3:00 a.m. to 6:00 a.m., the body has used up much of its supply. This aspect of rhythm explains why diabetics experience low blood sugar in the morning.

Although circadian rhythms have been studied for almost half a century, only recently has medical science entered the field to link the importance of the phenomenon to mental illness, dangers of nightshift work, jet lag, surgery, and drug administration.

The science of chronobiology and its far reaching effects in human health and conduct may begin to change medical therapy.
COPYRIGHT 1992 Vegetus Publications
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Copyright 1992 Gale, Cengage Learning. All rights reserved.

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Title Annotation:The Tyranny of Time: Solving the Mystery of Our Inner Clockwork; includes related article on stress
Publication:Nutrition Health Review
Article Type:Cover Story
Date:Jan 1, 1992
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