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 biorhythms: The physical curve with its cycle of 23 days, the emotional curve with 28 days and the mental curve with 33 days.
Below is a link that can calculate your biorythm state for today (you stick in your date of birth and it does the rest).
biorythm calculator

