Biorhythms

• PRINCIPAL PROPOSED USES: Physiological and psychological optimization
• OTHER PROPOSED USES: Industrial safety, sports performance, understanding mood, making decisions

DEFINITION: The theory that natural cycles regulate a person’s body, mentation, and emotions.

Overview

Biorhythm theory was conceived by Wilhelm Fliess, a German physician, and Hermann Swoboda, an Austrian psychologist, in the late nineteenth century. The two believed that basic human functions occur in periods of twenty-three and twenty-eight days. Associating the latter figure with the menstrual cycle, Fliess called the twenty-eight-day cycle female, or emotional, and the twenty-three-day cycle male, or physical. In the 1920s, Alfred Teltscher, an engineering professor, perceived a thirty-three-day intellectual cycle based on observations of his students’ performances.

Biorhythms did not claim wide popularity until the 1970s. Subsequently, additional cycles of thirty-eight, forty-three, and fifty-three days were proposed, as were cycles that combine two of the original three.

Mechanism of Action

Biorhythm proponents have not identified specific mechanisms that produce them. Each person’s biorhythms are said to begin at birth and remain regular afterward, although some proponents claim that arrhythmia can occur.

In classic three-cycle theory, the twenty-three-day physical cycle governs coordination, strength, endurance, sexual vigor, metabolism, and resistance to illness. The twenty-eight-day emotional cycle regulates temperament, nervous reactions, fantasy, and desires. The thirty-three-day intellectual cycle affects reasoning, alertness, judgment, memory, and sense of purpose.

The cycles fluctuate like a sine wave (a mathematical function) with positive and negative polarities. The nadir of a cycle’s negative polarity is called a critical (or transition) day because it is the least favorable day for an activity associated with the physiological or psychological states managed by a cycle; conversely, the acme of the positive polarity is the most favorable day for such an activity. A relatable example of an interruption in one's biorhythm is jet lag following a long flight.

Uses and Applications

Proponents insist that biorhythm cycles in themselves do not determine behavior because each person’s environment influences their expression. Instead, biorhythms enable a person to prepare for the best and worst times for any given activity. For instance, a person should not participate in a sport or have surgery on the critical day of the physical cycle, should avoid proposing marriage on the critical day of the emotional cycle, and should not take an examination on the critical day of the intellectual cycle. During the cycles’ positive polarities, these activities are more likely to turn out well. Biorhythm theory posits that it can predict performance, allow someone to understand their mood swings and emotional states, help an individual make important decisions, and improve self-awareness.

Scientific Evidence

Studies supporting biorhythm theory exist but fall short of scientific rigor because they depend on anecdotal evidence, have statistical or mathematical flaws, or are based on subjective assumptions and ad hoc hypotheses. Many peer-reviewed studies and mathematical analyses demonstrate that the predictions of biorhythms are no more accurate than chance. Many label biorhythms a pseudoscience and believe it has no therapeutic value and cannot treat any medical conditions.

Choosing a Practitioner

People wanting to discover their own cycles can do so without the help of a practitioner. Online calculators and calendars are also available for this process.

Bibliography

"Circadian Rhythm Disorders: Symptoms, Treatment & Types." Cleveland Clinic, 23 Jan. 2024, my.clevelandclinic.org/health/diseases/12115-circadian-rhythm-disorders. Accessed 10 Dec. 2025.

Emery, Patrick, and Frédéric Gachon. “Biological Rhythms: Living Your Life, One Half-Day at a Time.” Npj Biological Timing and Sleep, vol. 2, no. 1, 2025, p. 21, doi:10.1038/s44323-025-00037-1. Accessed 10 Dec. 2025.

"Everything You Need to Know about Biorhythm." UR Life, 13 May 2024, ur.life/article/everything-you-need-to-know-about-biorhythm. Accessed 10 Dec. 2025.

Gittelson, Bernard. Biorhythm: A Personal Science, 1997-1999. 10th ed., Grand Central, 1996.

Hines, Terence. "Biorhythm Theory: A Critical Review." Paranormal Borderlands of Science, edited by Kendrick Frazier, Prometheus Books, 1991.

Smith, Jonathan C. Critical Thinking: Pseudoscience and the Paranormal. 2nd ed., John Wiley & Sons, 2018.

West, Peter. Surf Your Biowaves: Use Your Biorhythms to Bring You Success. Quantum, 1999.