Submitted Successfully!
To reward your contribution, here is a gift for you: A free trial for our video production service.
Thank you for your contribution! You can also upload a video entry or images related to this topic.
Version Summary Created by Modification Content Size Created at Operation
1 handwiki -- 1898 2022-11-17 01:39:54

Video Upload Options

Do you have a full video?


Are you sure to Delete?
If you have any further questions, please contact Encyclopedia Editorial Office.
HandWiki. Biorhythm. Encyclopedia. Available online: (accessed on 21 June 2024).
HandWiki. Biorhythm. Encyclopedia. Available at: Accessed June 21, 2024.
HandWiki. "Biorhythm" Encyclopedia, (accessed June 21, 2024).
HandWiki. (2022, December 01). Biorhythm. In Encyclopedia.
HandWiki. "Biorhythm." Encyclopedia. Web. 01 December, 2022.

A biorhythm (from Greek βίος – bios, "life" and ῥυθμός – rhuthmos, "any regular recurring motion, rhythm") is an attempt to predict various aspects of a person's life through simple mathematical cycles. The theory was developed by Wilhelm Fliess in the late 19th century, and was popularized in the United States in late 1970s. Scientific analysis shows that biorhythms have no more predictive power than chance, providing no evidence for their existence. "The theory of biorhythms is a theory that claims our daily lives are significantly affected by rhythmic cycles."

biorhythm daily lives biorhythms

1. Hypothesis

Basic rhythm details
  • Physical cycle
    • 23 days; Circavigintan
    • coordination
    • strength
    • well-being
  • Emotional cycle
    • 28 days; Circatrigintan
    • creativity
    • sensitivity
    • mood
    • perception
    • awareness
  • Intellectual cycle
    • 33 days; Circatrigintan
    • alertness
    • analytical functioning
    • logical analysis
    • memory or recall
    • communication
The Biorhythm Chart when a person was born [1].

According to the theory of biorhythms, a person's life is influenced by rhythmic biological cycles that affect his or her ability in various domains, such as mental, physical and emotional activity. These cycles begin at birth and oscillate in a steady (sine wave) fashion throughout life, and by modeling them mathematically, it is suggested that a person's level of ability in each of these domains can be predicted from day to day. The theory is built on the idea that the biofeedback chemical and hormonal secretion functions within the body could show a sinusoidal behavior over time.

Most biorhythm models use three cycles: a 23-day physical cycle, a 28-day emotional cycle, and a 33-day intellectual cycle.[2] Although the 28-day cycle is the same length as the average woman's menstrual cycle and was originally described as a "female" cycle (see below), the two are not necessarily in synchronization. Each of these cycles varies between high and low extremes sinusoidally, with days where the cycle crosses the zero line described as "critical days" of greater risk or uncertainty.

The numbers from +100% (maximum) to -100% (minimum) indicate where on each cycle the rhythms are on a particular day. In general, a rhythm at 0% is crossing the midpoint and is thought to have no real impact on your life, whereas a rhythm at +100% (at the peak of that cycle) would give you an edge in that area, and a rhythm at -100% (at the bottom of that cycle) would make life more difficult in that area. There is no particular meaning to a day on which your rhythms are all high or all low, except the obvious benefits or hindrances that these rare extremes are thought to have on your life.

In addition to the three popular cycles, various other cycles have been proposed, based on linear combination of the three, or on longer or shorter rhythms.[3]

1.1. Calculation

Theories published state the equations for the cycles as:

  • physical: [math]\displaystyle{ \sin(2\pi t/23) }[/math],
  • emotional: [math]\displaystyle{ \sin(2\pi t/28) }[/math],
  • intellectual: [math]\displaystyle{ \sin(2\pi t/33) }[/math],

where [math]\displaystyle{ t }[/math] indicates the number of days since birth. Basic arithmetic shows that the combination of the simpler 23- and 28-day cycles repeats every 644 days (or 1-3/4 years), while the triple combination of 23-, 28-, and 33-day cycles repeats every 21,252 days (or 58.18+ years).

2. History

Kosmos 1.
Casio Biolator.
Japanese Biomate biorhythm calculator.

The notion of periodic cycles in human fortunes is ancient; for instance, it is found in natal astrology and in folk beliefs about "lucky days". The first studies surrounding certain “rhythms” and “life cycles” began in the 19th century, and “were successfully called Biorhythms.” The word biorhythm consists of two terms “bios” and “rhythmos” which are derived from Greek terms which translate to “life” and “rhythm".[4] The 23- and 28-day rhythms used by biorhythmists, however, were first devised in the late 19th century by Wilhelm Fliess, a Berlin physician and patient of Sigmund Freud. Fliess believed that he observed regularities at 23- and 28-day intervals in a number of phenomena, including births and deaths. He labeled the 23-day rhythm "male" and the 28-day rhythm "female", matching the menstrual cycle.

In 1904, Viennese psychology professor Hermann Swoboda came to similar conclusions. Alfred Teltscher, professor of engineering at the University of Innsbruck, developed Swoboda's work and suggested that his students' good and bad days followed a rhythmic pattern; he believed that the brain's ability to absorb, mental ability, and alertness ran in 33-day cycles.[3] One of the first academic researchers of biorhythms was Estonian-born Nikolai Pärna, who published a book in German called Rhythm, Life and Creation in 1923.

The practice of consulting biorhythms was popularized in the 1970s by a series of books by Bernard Gittelson, including Biorhythm — A Personal Science, Biorhythm Charts of the Famous and Infamous, and Biorhythm Sports Forecasting. Gittelson's company, Biorhythm Computers, Inc., made a business selling personal biorhythm charts and calculators, but his ability to predict sporting events was not substantiated.[5]

Charting biorhythms for personal use was popular in the United States during the 1970s; many places (especially video arcades and amusement areas) had a biorhythm machine that provided charts upon entry of date of birth. Biorhythm programs were a common application on personal computers; and in the late 1970s, there were also handheld biorhythm calculators on the market, the Kosmos 1 and the Casio Biolator.[6][7] Biorhythm charts appeared in the Chicago Tribune from 1977 to 1979, and Gittelson wrote daily biorhythm charts for the Toronto Star from 1981 to 1985.[8]

Although biorhythms have declined in popularity (pop culture magazine Vice considered them "dead" by the mid 2010s[8]), there are free and proprietary apps and computer programs which have charting and analysis capabilities, as well as numerous websites that offer free biorhythm readings.

3. Critical Views

There have been some three dozen studies supporting biorhythm theory, but according to a study by Terence Hines, all of those had methodological and statistical errors.[9] Hines rejected 134 biorhythm studies and concluded that the theory is not valid.[9]

Supporters continued to defend the theory after Hines' review, causing other scientists to consider the field as pseudoscience:

An examination of some 134 biorhythm studies found that the theory is not valid (Hines, 1998). It is empirically testable and has been shown to be false. Terence Hines believes that this fact implies that biorhythm theory 'can not be properly termed a pseudoscientific theory'. However, when the advocates of an empirically testable theory refuse to give up the theory in the face of overwhelming evidence against it, it seems reasonable to call the theory pseudoscientific. For, in fact, the adherents to such a theory have declared by their behaviour that there is nothing that could falsify it, yet they continue to claim the theory is scientific. (from Carroll's "The Skeptic's Dictionary")[10]:175

The physiologist Gordon Stein in the book Encyclopedia of Hoaxes (1993) has written: "Both the theoretical underpinning and the practical scientific verification of biorhythm theory are lacking. Without those, biorhythms became just another pseudoscientific claim that people are willing to accept without required evidence. Those pushing biorhythm calculators and books on a gullible public are guilty of making fraudulent claims. They are hoaxers of the public if they know what they are saying has no factual justification."[11]

A 1978 study of the incidence of industrial accidents found neither empirical nor theoretical support for the biorhythm model.[12]

In Underwood Dudley’s book, Numerology: Or What Pythagoras Wrought, he provides an example of a situation in which a magician provides a woman her biorhythm chart that supposedly included the next two years of her life. The women sent letters to the magician describing how accurate the chart was. The magician purposely sent her a biorhythm chart based on a different birthdate. After he explained that he sent the wrong chart to her, he sent her another chart, also having the wrong birthdate. She then said that this new chart was even more accurate than the previous one.[13] This shows that people are willing and have the capacity to believe in just about anything. Although this may not have been used to disprove biorhythms, it brings attention to the subjective affirmation and verification of biorhythms in general.[14]

Wilhelm Fliess "was able to impose his number patterns on virtually everything".[15] With this, he convinced others of his findings that cycles happen within men and women every 23 and 28 days with his idea of biorhythms. The issue with this is that in Fliess’s equation, n = 23x +28y, there can be infinitely many solutions for x and y.[16] Fliess is so connected with the numbers 23 and 28 that he can virtually make any significance from them within the biorhythm theory.

Skepticism is the idea that “No scientific statements of fact should be taken on faith. All statements should be carefully scrutinized for invalid arguments and errors of fact and any such errors should be made public immediately”.[17] For this reason alone, that is why this theory has been tested as much as it has through the decades. Still, many scientists are skeptic of this theory. In nature, there are certain circadian rhythms that have proven to show that they exist in many organisms, such as sleep. Scientists are skeptic of biorhythms mainly because these other circadian rhythms are regular cycles that can vary in length based on environmental factors and other types of factors that may contribute to this change.[18] If these factors were to come into play with biorhythms, the cycles would never be able to maintain their precise period lengths as they are indicated within the hypothesis of the theory.

3.1. Additional Studies Supporting the Classification of Biorhythms as Pseudoscientific

Several controlled, experimental studies have been conducted in order to investigate the validity of biorhythms.[19][20][21] Such studies have yielded results that provide support for the classification of biorhythms as a pseudoscience. These studies include:

Prytula and Colleagues (1980)[19]

They found that subjects did not perceive biorhythms generated from random dates as being any more or less valid than those constructed using their birthdays.[19] Further, these subjects did not display any differences in rating between the 'valid' (i.e., constructed using the subject's birthday), and random biorhythms. Overall, the results of this experiment provide data supporting the argument against the perceived validity of biorhythms.[19]

James (1984)[20]

James hypothesized that if biorhythms were rooted in science, then each proposed biorhythm cycle would contribute to task performance.[20] Further, he predicted that each type of biorhythm cycle (i.e., intellectual, physical, and emotional) would be most influential on tasks associated with the corresponding cycle type. For example, he postulated that intellectual biorhythm cycles would be most influential on academic testing performance.[20] In order to test his hypotheses, James observed 368 participants, noting their performance on tasks associated with intellectual, physical, and emotional functioning. Based on data collected from his experimental research, James concluded the there was no relation between subjects' biorhythmic status (on any of the three cycle types), and their performance on the associated practical tests.[20]

Peveto (1980)[21]

Peveto examined the proposed relationship between biorhythms and academic performance, specifically in terms of reading ability.[21] Through examination of the data collected, Peveto concluded that there were no significant differences in the academic performance of the students, in regards to reading, during the high, low, or critical positions of neither the physical biorhythm cycle, the emotional biorhythm cycle, nor the intellectual biorhythm cycle. As a result, it was concluded that biorhythm cycles have no effect on the academic performance of students, when academic performance was measured using reading ability.[21]


  1. "Biorhythm chart". 
  2. These cycles are to be adjusted based on the person's personal day clock which may run from 22 hours to 27 hours although 23-25 is the norm. Two ways you can find your personal day clock is grip test and body temperature every 15 minutes for a few days or easier same time each day for a few months.
  4. "The History of Biorhythms". 
  5. Hoffmann, Frank W., and William G. Bailey, Mind and Society Fads, 1992.
  7. "MyCalcDB : Calculator Casio BIOLATOR aka H-801". 
  8. Heisel, Andrew (15 September 2015). "Biorhythms: The 1970s Fad That Won a Super Bowl, Killed Clark Gable, and Made America Gaga for Computers | VICE Sports" (in en). VICE Sports. Retrieved 27 December 2016. 
  9. Hines, Terence (1998). "Comprehensive Review of Biorhythm Theory" (PDF (summary)). Psychological Reports 83 (1): 19–64. doi:10.2466/PR0.83.5.19-64. PMID 9775660. Archived from the original on February 12, 2009. Retrieved 2008-01-13. 
  10. Stefan Ploch (2003). "Metatheoretical problems in phonology with Occam's Razor and non-ad-hoc-ness". in Jonathan Kaye, Stefan Ploch. Living on the edge: 28 papers in honour of Jonathan Kaye. Studies in generative grammar. Walter de Gruyter. pp. 166, 174–176, 186, footnotes 15 and 17 in page 199. ISBN 978-3-11-017619-3. "the following quote about the pseudoscientific biorhythm theory [p. 174–175] (...) we can eliminate ad hoc hypotheses (i.e. arbitrariness) that are the hallmark of all pseudosciences (astrology, biorhythm theory, (...) [p. 176] Unfortunately, in the case of the most socially successful [not scientific] theories, just as in the case of astrology and biorhythm "theory", we are dealing with something that resembles quackery closely. [p.186] (...) what matters is that falsifying data is systematically discounted in this pseudotheory. [p. 199]" .
  11. Stein, Gordon. (1993). Encyclopedia of Hoaxes. Gale Group. p. 161. ISBN:0-8103-8414-0
  12. Persinger, MA; Cooke, WJ; Janes, JT (1978). "No evidence for relationship between biorhythms and industrial accidents". Percept mot Skills 46 (2): 423–6. doi:10.2466/pms.1978.46.2.423. PMID 662540.
  13. Dudley, Underwood (1997). Numerology: Or What Pythagoras Wrought. The Mathematical Association of America. 
  14. Carroll, Robert Todd. "Biorhythms". 
  15. Gardner, M. Science, Good, Bad, and Bogus. 
  16. Dudley, Underwood. Numerology, or, What Pythagoras wrought. 
  17. Casti, John L.. Paradigms Lost. 
  18. Biersdorfer, J.D.. "Strange Things Happening? Blame Your Biorhythms". New York Times. 
  19. Prytula, Robert E (1980). "Studies on the perceived predictive accuracy of biorhythms". Journal of Applied Psychology 65 (6): 723–727. doi:10.1037/0021-9010.65.6.723. ISSN 0021-9010.
  20. James, Arthur (1984). "The validity of 'biorhythmic' theory questioned". British Journal of Psychology 75 (2): 197–200. doi:10.1111/j.2044-8295.1984.tb01891.x. ISSN 0007-1269. PMID 6733392.
  21. Peveto, Natalia (1980-01-01). "The Relationship of Biorhythms to Academic Performance in Reading.". LSU Historical Dissertations and Theses. 
Subjects: Others
Contributor MDPI registered users' name will be linked to their SciProfiles pages. To register with us, please refer to :
View Times: 3.0K
Entry Collection: HandWiki
Revision: 1 time (View History)
Update Date: 01 Dec 2022
Video Production Service