The biorhythms according to Swoboda/Fließ are based on three “rhythms” with different period lengths:
(P) physical rhythm (23 days), (S) emotional rhythm (28 days), (I) mental rhythm (33 days)
At birth, these rhythms should begin positively in waves with their first period, after half a year Period length crosses the zero line and then enters a negative phase. At the end of the period there is a change back into the positive area. All transitions, i.e. from positive to negative and Conversely, critical days, i.e. potentially bad days, should be. There is now a transition in all three phases on the same day, according to biorhythmic theory, this can have crisis-like consequences - while the coincidence of positive days should result in particularly good days. The general condition is usually reported as the average of the three curves.
The basis for this simple calculation was developed at the beginning of the 20th century by the Viennese psychologist Hermann Swoboda and the Berlin doctor Wilhelm Fließ. Fliess believed he had discovered consistent regularities in his patients medical records and initially formulated this in his period theory. They tried to discover a law behind the good and bad moments of a life. The biorhythm according to Swoboda/Fließ repeats itself every 23 × 28 × 33 days, corresponding to around 58 years and 2 months, in the course of an average human life, at most once.