The history of biorhythms is an interesting one. Unlike psychoanalysis, the biorhythm theory has two "fathers" - Dr. Hermanna Swoboda and Dr. Wilhelm Fliess. Dr. Hermanna Swoboda was a professor of psychology at the University of Vienna. Dr. Wilhelm Fliess was a nose and throat specialist in Berlin. Like so many important scientific discoveries, both Fliess and Swoboda were working along very similar lines with almost no knowledge of each other's work. It is quite extraordinary that these two scientists, despite doing independent research, came to virtually identical conclusions.

Both Swoboda and Fliess found psychology intriguing and due to books and information beginning to surface at the time, took an interest in human cycles. Swoboda published this paper at the Universal of Vienna in 1900:

"Life is subject to consistent changes. This understanding does not refer to changes in our destiny or to changes that take place in the course of life. Even if someone lived a life entirely free of outside forces, of anything that could alter his mental and physical state, still his life would not be identical from day to day. The best of physical health does not prevent us from feeling ill sometimes, or less happy then usual."

Analyzing dreams, ideas and creative impulses of his patients, Swoboda noticed very regular patters or rhythms. Some artists might be familiar with these dry spells and then frenzies of creations with predictable variations. He also observed that new mothers began to show anxiety about their infants whenever a critical day occurred or was about to occur.

Swoboda was an exacting researcher and would keep detailed records on his patient's tissue swelling and onsets of illness or fever. Slowly, a rhythm began to appear. These physical phenomena would happen in a 23-day cycle, giving him the power to predict their recurrence. Also, the creative or emotional 28-day rhythm was discovered.

Swoboda's discovery of these two basic biorhythms led him to write a succession of distinguished and widely-popular books explaining and developing the ideas of human cycles. First of these books, published in 1904, is titled The Periods of Human Life (in their psychological and biological significance). His second book titled Studies on the Basis of Psychology further elaborated his work on creativity and the recurrence of dreams. In 1909 he published an instruction booklet which included a slide rule to calculate critical days called, The Critical Days of Man.

Swoboda's best book, and one of his last, was a volume of almost 600 pages titled The Year of Seven. Much of that work was devoted to proving biorhythm theory by giving a mathematical analysis of how the timing of births tends to be rhythmic and predictable from generation to generation within the same family.

Wilhelm Fliess on the other hand did not get nearly as much gratification from his discovery as Swoboda. He did introduce Sigmund Freud, a friend of his, to Biorhythms around the turn of the century. Freud, well known as the father of modern psychology, was very interested in human behavior and was fascinated by Fliess's work. During the course of five years they wrote over a hundred letters to each other discussing their respective discoveries and research. Both Fliess and Freud were interested in human bisexuality. Fliess begun to prove cellular bisexuality through his research of Biorhythms realizing that both men and women had an emotional cycle that was the same. He stated that Women are more influenced by the emotional cycle and men are more affected by the physical cycle. He concluded, due to cellular bisexuality both male and females have both rhythms (saying that men have a pseudo menstrual cycle, if you will). In 1909, Fliess published a book entitled The Course of Life, which spurred other doctor, Hans Schlieper, to write a book on Biorhythms called The Year in Space.