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# biorhythm

[bahy-oh-rith-uhm]
biorhythm or biological rhythm, cyclic pattern of changes in physiology or in activity of living organisms, often synchronized with daily, monthly, or yearly environmental changes. Rhythms that vary according to the time of day (circadian rhythms), in part a response to daylight or dark, include the opening and closing of flowers and the nighttime increase in activity of nocturnal animals. Circadian rhythms also include activities that occur often during a 24-hour period, such as blood pressure changes and urine production. Annual cycles, called cirannual rhythms, respond to changes in the relative length of periods of daylight and include such activities as migration and animal mating. Marine organisms are affected by tide cycles. Although the exact nature of the internal mechanism is not known, various external stimuli—including light, temperature, and gravity—influence the organism's internal clock; in the absence of external cues, the internal rhythms gradually drift out of phase with the environment.

Periodic biological fluctuation in an organism corresponding to and in response to periodic environmental change, such as day and night or high and low tide. The internal mechanism that maintains this rhythm even without the apparent environmental stimulus is a “biological clock.” When the rhythm is interrupted, the clock's adjustment is delayed, accounting for such phenomena as jet lag when traveling across time zones. Rhythms may have 24-hour (circadian rhythm), monthly, or annual cycles. Seealso photoperiodism.

Learn more about biological rhythm with a free trial on Britannica.com.

A biorhythm (from Greek βιορυθμός - biorhuthmos) is a hypothetical cycle in physiological, emotional, or intellectual well-being or prowess. "Bio" pertains to life and "rhythm" pertains to the flow with regular movement. Biorhythms theory has no more predictive power than chance, and has been labeled a pseudoscience by skeptics.

## Basic theory

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
• analytical functioning
• logical analysis
• memory or recall
• communication

The theory of biorhythms claims that one's life is affected by rhythmic biological cycles, and seeks to make predictions regarding these cycles and the personal ease of carrying out tasks related to the cycles. These inherent rhythms are said to control or initiate various biological processes and are classically composed of three cyclic rhythms that are said to govern human behavior and demonstrate innate periodicity in natural physiological change: the physical, the emotional, and the intellectual (or mental) cycles. Others claim there are additional rhythms, some of which may be combinations of the three primary cycles. Some proponents think that biorhythms may be potentially related to bioelectricity and its interactions in the body.

Basic rhythms follow certain facets of physiological cycles, though they may include others, and the details may vary depending on the source. The three classical cycles of biorhythms are endogenous infradian rhythms. The theory's basis lies in physiological and emotional cycles. They are often represented graphically as either symmetric or asymmetric waveforms, though most theories rely on symmetric forms. The most commonly used form is the sinusoidal waveform, which is thought to be a plausible representation of a bioelectric activity cycle. Due to this sinusoidal nature, the cyclical flow of bioelectric activity undergoes periodic reverses in direction. Each cycle oscillates between a positive phase [0%..100%] and a negative phase [-100%..0%], during which bioelectric activity strengthens and weakens. The waveforms start, in most theories, at the neutral baseline (0%) at the time of birth of each individual. Each day that the waveform again crosses this baseline is dubbed a critical day, which means that tasks in the domain of the cycle are far more erratic than on other non-critical days. The purpose of mapping the biorhythmic cycles is to enable the calculation of critical days for performing or avoiding various activities.

The classical definition (derivatives of the original theory exist) states that one's birth is an unfavorable circumstantial event, as is the day about 58 years later when the three cycles are again synchronised at their minimum values. According to the classical definition, the theory is assumed to apply only to humans. In the classical theory, the value of each cycle can be calculated at any given time in the life of an individual, and there are web sites that do exactly that.

## Related terminology

Biorhythmics is either a protoscientific branch or a pseudoscience, depending on opinion, that studies biorhythms or deal with biorhythms. Biorhythmic study focuses on physiological, emotional, and intellectual processes and its forecasting. Biorhythm phenomena are observable human conditions which can be detailed and explained by biorhythmics. These conditions are bound by the variables that exist in the body. Certain facets of biorhythmics are likened by proponents to concepts found in weather forecasting (commonly known as meteorology).

Chronobiology is a branch of biology that studies rhythms in living beings. Unlike biorhythm, its status as a science is unquestioned.

### Biological rhythm cycles

• Ultradian are the biological rhythms having extremely short cycles (lasting less than 24 hours).
• Circadian are the biological rhythms having a period of about 24 hours (lasting a day).
• Infradian are biological rhythms composed of long-term cycles (lasting several days).
• Exogenous are cycles influenced by external factors.
• Endogenous are cycles not influenced by external changes.
• Circatrigintan are cycles that recur every month (around 25-35 days).
• Circavigintan are cycles that recur triweekly (around 17-23 days).
• Circadiseptan are cyles that occur biweekly (around 12-17 days).
• Circannual are cycles that recur every year (around 365 days).

## Application

In the workplace, railroads and airlines have experimented the most with biorhythms. A pilot describes the Japanese and American attitudes towards biorhythms. He acknowledges, researching his pilot logbook, that his greatest errors of judgment occurred during critical days, but concludes that an awareness of one's critical days and paying extra attention is sufficient to ensure safety. A former United Airlines pilot and user of the Biorhythms for Windows program confirms that United Airlines used biorhythms until the mid-1990s, while the Nippon Express air freight still used biorhythms.

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.

## History

The classical theory originated at the turn of the 19th century, between 1897 and 1902, from observational research.

Hermann Swoboda, professor of psychology at the University of Vienna, who was researching periodic variations in fevers, looked into the possibility of a rhythmic change in mood and health. He collected data on reaction to pain, outbreak of fevers, illnesses, asthma, heart attacks, and recurrent dreams. He concluded that there was a 23-day physical cycle and a 28-day emotional cycle.

Wilhelm Fliess, a nose and throat specialist and reportedly a numerologist, was independently researching the occurrences of fevers, recurrent illnesses and deaths in his patients. He too came to the conclusion that there was a 23 and a 28-day rhythm. Fliess' theories were of great interest and importance to Sigmund Freud during his early work in developing his psychoanalytic concepts.

Alfred Teltscher, professor of engineering at the University of Innsbruck, observed that his students' good days and bad days followed a rhythmic pattern of 33 days. Teltscher found that the brain's ability to absorb, mental ability, and alertness ran in 33 day cycles. In the 1920s, Dr. Rexford Hersey (psychologist; Pennsylvania, America) also reportedly made contributions to the classical theory.

These three biorhythms compose the classical theory. The classical theory has been studied, especially in Germany, Japan, and the United States, with conflicting results. Various modern derivatives exist of the classical theory.

## Plausibility

Proponents of biorhythmics call it an established interdisciplinary area of scientific endeavor which is still speculative - a protoscience. Critics state that biorhythms are based only upon numerological associations. The plausibility of biorhythmics is contested by mathematicians, biologists and other scientists. The most basic assertion is that, even if physiological rhythms do exist, why would they begin precisely on the day of our birth?

Biorhythmics has echoes of chronobiology, the study of biological rhythms. Through medical research, doctors have found that there are periodic biological cycles in a person's lifespan, such as the circadian rhythm (from Latin circa diem; literally, "about a day"), but few doctors believe they correspond to those described as "biorhythms". To proponents, these discoveries (among others) demonstrate that people are affected by physiological, emotional and intellectual rhythms, though the exact relationships to the biorhythm cycles are not precisely understood. Studies regarding the effects of biorhythms on the human condition are still conducted.

The Biorhythm theory is often treated as falsely claiming scientific validity. Biorhythm critics' responses range from opposing it as harmful to ignoring it or treating it as entertainment. Some of the criticisms of the various theories in the category of biorhythmics are:

• The choices of periodical function, frequency and phase are arbitrary.
• The assumption is made that the cycles are the same for everyone.
• The frequency is assumed to be constant.
• Evidence tends to be anecdotal.
• Arguments are made based in ignorance of number theory.
• Tests of the hypothesis have basic flaws.
• The quantitative generalizations of complex human behavior are inadequate.
• Hypotheses are not formulated precisely.
• Experimental data fail peer review.
• Experiments cannot be replicated.
• Some unscrupulous practitioners resemble professional fortune-telling fraud artists.

Some biorhythm critics say that biorhythms can be thrown off by such occurrences in the calendar as the beginning of the new year, holidays, or something as simple as the start of the week.

There have been some three dozen studies supporting biorhythm theory but all of them have suffered from methodological and statistical errors. An examination of some 134 biorhythm studies found that the theory is not valid.

## Calculation

The equations for the curves are

• physical: $sin\left(2pi t/23\right)$,
• emotional: $sin\left(2pi t/28\right)$,
• intellectual: $sin\left(2pi t/33\right)$,
• intuitive: $sin\left(2pi t/38\right)$,

where $t$ indicates the number of days since birth.

## External links, references, and resources

### Books

• Bartel, Pauline C., "Biorhythm : discovering your natural ups and downs", An Impact book. ISBN 0-531-01355-3
• Bentley, Evie, "Awareness : biorhythms, sleep, and dreaming". ISBN 0-415-18872-5
• Crawley, Jacyntha, The Biorhythm Kit, UK: ISBN 1-85906-032-3, London Biorhythm Company Limited.
• Edlund, Matthew. "Psychological time and mental illness". 1987. ISBN 0-89876-122-0
• Evans, James R., (ed.) and Manfred Clynes (ed.), "Rhythm in psychological, linguistic, and musical processes". ISBN 0-398-05235-2
• Hodgkins, Zerrin "Biomatch Z". 1998. ISBN 0-9531983-0-8
• Lapointe, Fernand, "Biorythmie : comment prâevoir vos bons et mauvais jours". ISBN 0-88566-029-3
• Roche, James, "Biorhythms at your fingertips". ISBN 0-7137-1562-6
• Thommen, George S., "Is This Your Day". 1973. ISBN 0-517-00742-8
• Debarbieux, Patrick, "l'ABC des biorythmes". 1999. ISBN 2-7339-0615-1

### Research publications

#### Biorhythmics

• Hines, T. M., "Comprehensive review of biorhythm theory". Psychology Department, Pace University, Pleasantville, NY. Psychol Rep. 1998 Aug;83(1):19-64. (ed. concluded that biorhythm theory is not valid.)
• D'Andrea, V. J., D.R. Black, and N. G. Stayrook, "Relation of the Fliess-Swoboda Biorhythm Theory to suicide occurrence". J Nerv Ment Dis. 1984 Aug;172(8):490-4. (ed. concluded that there was a validity to biorhythm when the innovative methods of the study are put to use.)
• Laxenaire M., and O. Laurent, "What is the current thinking on the biorhythm theory?". Ann Med Psychol (Paris). 1983 Apr;141(4):425-9. [French](ed. Biorhythm theory is disregarded by the medical world though it has achieved a bit of fame with the public)
• Wolcott, J. H., R. R. McMeekin, R. E. Burgin, and R. E. Yanowitch, "Correlation of general aviation accidents with the biorhythm theory". Hum Factors. 1977 Jun;19(3):283-93.
• Khalil, T. M., and C. N. Kurucz, "The influence of 'biorhythm' on accident occurrence and performance". Ergonomics. 1977 Jul;20(4):389-98.
• "Biorhythm in gynecology--a renaissance of Fliess' theory of periodicity?". Arch Gynecol. 1979 20 July;228(1-4):642. [German]
• Nijsten, M.W., and S. E.Willemsen, "Accidents a matter of chance? The significance of lunar phases and biorhythms in trauma patients". Ned Tijdschr Geneeskd. 1991 21 December;135(51):2421-4. [Dutch] (ed. 'critical' biorhythm days were not found to increase the number of accidents experienced by subjects.)

#### Chronobiology related

• Hastings, Michael, "". Clinical review. BMJ 1998;317:1704-1707 19 December.
• U.S. Congress, Office of Technology Assessment, "". U.S. Government Printing Office, September 1991. Washington, DC. OTA-BA-463. NTIS PB92-117589
• Ashikari, M., Higuchi, S., Ishikawa, F., and Tsunetsugu, Y., "". Sunday, 25 August 2002
• "Biorhythm experiment management plan", NASA, Ames Research Center. Moffett Field, 1983.
• "Biological Rhythms and Human Adaptation to the Environment". US Army Medical Research and Materiel Command (AMRMC), US Army Research Institute of Environmental Medicine.
• Ebert, D., K.P. Ebmeier, T. Rechlin, and W.P. Kaschka, "Biological Rhythms and Behavior", Advances in Biological Psychiatry. ISSN 0378-7354

### Other resources

#### Skeptic resources

• Gardner, Martin. "Science: Good, Bad and Bogus", Fliess, Freud, and Biorhythm. Ch. 11. Prometheus Books, Buffalo, N.Y. 1981. ISBN 0-87975-573-3
• Hines, Terence M., "A comprehensive review of biorhythm theory". Reprinted from: Psychological Reports, August 1998, Psychology Department, Pace University
• Skeptic's Dictionary entry

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