Chronobiology: The Science of Time

About History and Three Basic Cycles of Chronobiology.

History of Chronobiology

Most of us have very little knowledge about the human body’s inner clock. However, a young science from Europe called Chronobiology has been gaining importance over the past 30 years. Chronobiology refers to the day-night cycle that affects the human organism when the earth rotates. Since the beginning of mankind, human history has been shaped by light and darkness. Genetically manifested timers reside deep in our bodies that control this fundamental rhythm. The more intelligently we absorb their information, the more useful it is. This connection is important in the prevention and treatment of diseases, as well as for the healing process.

The beginnings of Chronobiology date back to the 18th century. The astronomer Jean Jacques d’Ortous de Mairan reported daily leaf movements of the mimosa. Through experimentation he was able to show that the leaves continue to swing in a circadian rhythm, even in permanent darkness. Renowned scientists like Georg Christoph Lichtenberg, Christoph Wilhelm Hufeland, Carl von Linné, and—most importantly—Charles Darwin reported similar rhythmic phenomena. Yet it wasn’t until the 20th century when chronobiology research truly began. Wilhelm Pfeffer, Erwin Bünning, Karl von Frisch, Jürgen Aschoff, Colin Pittendrigh and Arthur Winfree are among its pioneers.

The Three Basic Cycles of Chronobiology

Infradian Rhythms (from the Latin “infra” meaning “under,” and “dies” meaning “day”) are rhythms that last more than 24 hours. These are repeated only every few days, weeks, months, or even once per year.
Good examples are seasonal rhythms such as bird migration, lunar rhythms (which follow the phases of the moon, or about 29.5 days) and semi-lunar rhythms (about 14 days) that are associated with tidal cycles. Another example is unpredictable rhythms (aka “non-circadian rhythms” that do not have any environmental correspondence) such as a woman’s menstrual cycle.

Ultradian Rhythms (from the Latin “ultra” meaning “over,” and “dies” meaning “day”) are biological rhythms that are shorter than 24-hours. There are many physiological functions of the human body that exemplify an ultradian rhythm. These rhythms have multiple cycles in one day. An adult, for example, has an exertion and rest cycle about every two hours.
Ultradian rhythms regulate physical, emotional and spiritual functions. They often last several hours and include the ingestion of food, circulation of blood, excretion of hormones, different stages of sleep and the human performance curve. These processes are built into our bodies in millions of ways. Some last merely seconds, such as the control of breathing. Some last only milliseconds, such as the majority of processes that take place in the cell on a microcirculatory level. Tidal rhythms (about 12.4 hours) are often observed in marine life, follow the transition of the tides from high to low and back and have a special function for many people living inside a surf zone.

Chronobiology Today

The field of chronobiology is rapidly expanding around the world. Medical professionals, researchers and the general population are beginning to see the benefits of using chronobiological principles in everything from medication administration to determining the most effective time of day to exercise. Chronobiology is being used in the study of genetics, endocrinology, ecology, sports medicine and psychology, to name a few.

The chronopharmacology branch of chronobiology has been especially lucrative. Thousands of studies have yielded information on how the precise timing of a medication or supplement can decrease side effects, have a more potent effect on the target organ system or disease and even completely disrupt a physiological process.

Many renowned institutions have added departments, labs and curriculum centered on the study of chronobiology. These institutions have provided groundbreaking research and insights that have helped shape modern medicine and the understanding of our innate biological rhythms. Melatonin, also referred to as the “mother hormone of chronobiology,” the effects of light on a variety of diseases and the phenomenon of chronotypes have been areas of particular interest.

While chronobiology is still considered a young science, the possibilities it presents are endless. Our methods of research are becoming more advanced and with that brings the reality that chronobiology will eventually become the leading scientific discipline.



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