What is Biorhythm?
At the beginning of the last century, Dr. Wilhelm Fliess noticed identical rhythms in the case histories of his patients. He observed active and passive phases in the physical, emotional and mental aspects of humans. From these observations he derived the principle of the biorhythm: The physical curve with its cycle of 23 days, the emotional curve with 28 days and the mental curve with 33 days.
Interpretation
When the curve of any cycle is above the midline, we experience a "high" in the corresponding field (physical, emotional or mental). If it is the physical curve, you will feel bodily well and, for example, if you were to have an operation the body would be more resilient. If it is the emotional curve, you will be in a good mood and your contact with other people will be positive. If it is the mental curve, your thought processes will be sharper, concentration will be easier and you may have a lot of ideas and insights.
When the curve of any cycle is below the midline, we experience a "low" in the corresponding field. If it is a physical low, you may feel weak and listless; if it is an emotional low, you may feel miserable and out of sorts; if it is a mental low, thinking can be foggy and concentration hard.
When any of the curves crosses the midline, this is a critical time in the corresponding field and if two curves cross the midline at the same point, this is a very critical time. Critical in the physical field means you may feel exhausted and it is better to avoid physical effort and operations. Critical in the emotional field means you may feel irritable and sad, and emotional outbreaks are likely so it is better to avoid conflicts and arguments. Critical in the mental field finally means sluggish thinking and it is better to postpone activities that demand a lot of concentration.