What is biorhythm?

Biorhythm theory holds that three regular cycles begin at birth and continue throughout life. Each cycle swings like a sine wave between a high phase and a low phase.

The three cycles

• Physical – 23 days: strength, stamina, resilience.
• Emotional – 28 days: mood, sensitivity, dealing with others.
• Intellectual – 33 days: concentration, memory, judgement.

There are also other, less common cycles, such as the 38-day intuitive cycle. It can be switched on in the calculator as a fourth curve – just as in WinBio.

On the day of birth all three curves stand at zero and then begin to rise. The value of a cycle follows from the number of days lived t and its period T: sin(2π · t / T).

Critical days

When a curve switches from its high to its low phase, or back, it crosses the centre line. These days are considered “critical”: the rhythm is in transition. When two or three crossings fall on the same day, it is called a double or triple critical day.

History

The idea dates back to the late 19th century. The Berlin physician Wilhelm Fliess described periods of 23 and 28 days, as did, independently, the Viennese psychologist Hermann Swoboda. The 33-day intellectual cycle was added in the 1920s. Biorhythm became popular in the 1970s, when pocket calculators and later home computers made the calculation available to everyone.

In the mid-1980s the DOS program SuperBio was created, followed in 1994 by WinBio for Windows, in four languages. biorhythm.com is their successor – read more in the history of SuperBio and WinBio.

What does science say?

Studies have found no link between biorhythm curves and performance, accidents or well-being. Biorhythm is therefore not a medical or scientific tool. Many people still enjoy it as a prompt to pay attention to themselves and to plan their day consciously.