Like almost all living beings, humans follow biological rhythms and cycles, which have proven to be vital in the course of development. The connections are explored by a rather young scientific discipline, chronobiology. Particularly well-known is the day-night-rhythm, which regulates work and resting phases and prehistorically closely with the light distribution during the day is connected.
The inner clock as a clock
The same applies to summer and winter time, which influence the human body through the sun's different levels of sunlight - long rest periods in winter minimize the energy requirement and ensure survival even long ago. Therefore, it used to be thought that the organism responds to an externally given rhythm.
However, we now know that we have our own clock, the internal clock. Although it reacts to external influences, it continues to tick even when environmental factors such as light are switched off. It is controlled by processes such as the release of the hormone melatonin.
Biorhythms: circulation of the body
The natural fluctuations of bodily functions as continuous changes in the organism in recurrent cycles are called biorhythms. Important biorhythms in humans are:
- the sleep-wake rhythm
- the activity cycle
- the food intake and drinking rhythm
- the body temperature rhythm
- endocrine rhythms
Other forms of a biological periodic are the female cycle, the heartbeat and the renewal of the blood cells.
These examples make it clear that humans are not only subject to a 24- to 25-hour beating rhythm controlled by the internal clock (circadian rhythm), but also to other shorter (ultraradian rhythm) or longer lasting cycles (infrared rhythm) play.
Biorhythmics as a pseudoscience
The term biorhythm is also used in the context of biorhythmics, a pseudoscience that assumes that life is undulating in three different duration (between 23 and 33 days) rhythms - the physical, emotional and intellectual. Based on the date of birth and gender, models are used to calculate good and bad days.
This speculative form of the laws was propagated by the physician Wilhelm Fleiß at the beginning of the 20th century and lacks the scientific basis.