Concepts of biological rhythmicity and chronobiology in the Holy Bible.

The way in which religious texts and sources depict the processes involved in the regulation of life is an interesting and rich topic. For example, the Holy Bible, the religious basis of Western civilization, is a document that includes references to medical, as well as historic cultural practices. Sun has already demonstrated that the Bible contains rich medical materials on different subjects in which the roots of modern medicine can be seen. We would like to expand this view to show that religious documents, with a focus on the Holy Bible, are illustrative of period understanding of life and human biological rhythmicity and chronobiology. Cyclical changes in the natural environment make the coordination of biological activities (events, durations and the timing among them) highly important for living species, including humans. Biological rhythms can be cued by the alternation of day and night, lunar cycles, as well as to the succession of the seasons. Chronobiology is a multidisciplinary field of biology that studies these biological rhythms. Physiological and behavioral characteristics (body temperature, alertness, daily performance, wake/ sleep cycle, feeding cycles, and activity/resting cycles) exemplify some of elements of human life that are regulated by natural cycles. When these rhythms are part of a 24-hour cycle (mostly regulated by light-dark cycles) they are called circadian rhythms. From a biological perspective, circadian rhythms are daily cycles of physiology and behavior that are driven by an endogenous oscillator with a period of approximately one day. When the rhythms have a period that closely follows the seasons, they are called circa-annual rhythms. One of the strongest influences on current biorhythms, and their evolution is the sun: Daily light-dark cycles and the seasonal changes in day length have great importance in regulating timing, but also these solar patterns, at evolutionary time scales, are responsible for the development of the mechanisms themselves. The importance of how natural cycles affect human activity and life rhythms is clearly expressed in religious documents, so too are ancient cultural traditions with cyclical natures (i.e., the 7 day week). For example, the Book of Genesis presents aspects of Earth and Life creation and regulation, and even mentions chronobiology. The First Book of Moses (Genesis) contains the following information concerning human (biological) rhythmicity (about circadian and circa-annual rhythms): ...And God said, Let there be light: and there was light. And God saw the light, that it was good: and God divided the light from the darkness. And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day... And God said, Let there be lights in the firmament of the heaven to divide the day ● Letter to the Editor