BIORHYTHMS. — By biorhythms (b.) we mean the rhythmic activities of living beings. In reality, every vital phenomenon is rhythmic: the very life of a species, with the birth, growth, and death of successive generations of individuals, is rhythmic; a rhythm is discernible in almost all organic functions: respiration, circulation, secretory and excretory phenomena, etc. Thus, many activities of living beings are rhythmic: wakefulness and sleep, nutrition, reproduction, etc. Even the activity of the individual cells that compose organisms is rhythmic.
Biorhythms include biological cycles, although these are considered separately as representing a series of more or less complex phenomena linked to living beings, by which one returns from a condition to the same. Thus, the life cycle from an egg, the cycle of organization of the elements that compose living matter such as carbon and nitrogen, the life cycle of parasites, etc. (v. Biological Cycles).
The rhythmicity of vital phenomena is to be sought in the rhythmicity of celestial phenomena, such as essentially the rotation of the earth around the sun and around its own axis and the rotation of the moon, and in the phenomena of the physical world in which plants and animals live, such as night and day, the seasons, tides, winds, etc.
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