Biorhythms

Biorhythms are cycles that, according to biorhythm theory, govern a person's physical, emotional and intellectual capacities. The theory, which research has not supported, holds that three cycles, of 23 days (physical), 28 days (emotional) and 33 days (intellectual), start at birth and rise and fall in a regular wave pattern throughout life.

Description

Key terms

• A critical day is a day on which one of the cycles crosses its midpoint, said by followers to be a time when mistakes are more likely.
• Chronobiology is the science of real biological rhythms, such as daily (circadian) rhythms, which have measurable physiological signs. It is a different thing from biorhythm theory, even though the word "biorhythm" is sometimes used loosely within it.

The three cycles

In biorhythm theory, the 23-day cycle affects physical aspects of behaviour, the 28-day cycle the emotions, and the 33-day cycle intellectual functions. The cycles are said to be fixed from birth and not to vary at all with a person's environment or physiology.

Charts and critical days

Karl Kruszelnicki, writing for ABC Science in 2013, summarised what popular books of the 1970s claimed. Each cycle was said to swing above and below a central "zero line". When a cycle was high, a person was supposed to do well in the qualities it governed: strength, coordination and endurance for the physical cycle; feelings such as empathy, intuition and optimism for the emotional cycle; and memory, concentration and reasoning for the intellectual cycle. A day on which a cycle crossed the zero line was called a "critical day", when behaviour was said to be less predictable, and more so when two or three cycles crossed on the same day.

The Encyclopedia of Occultism and Parapsychology gives a similar account. It describes the physical cycle as covering strength, energy and endurance, the emotional cycle sensitivity, intuition and creativity, and the intellectual cycle thinking, reasoning and ambition. Charts plot the high and low points of each cycle, and days when two or three cycles cross are treated as times of stress. Followers of the theory say that by studying these charts a person can pick the best days for effort and avoid overstretching themselves on low days.

A 1981 article in South Australia's Port Lincoln Times set out the practice as local followers understood it. Each cycle begins at birth and has an active half, when a person works more efficiently, and a passive half, when efficiency falls. The changeover days are "critical" days on which mistakes are more likely, and followers said that being aware of them helps a person get through them.

What the evidence says

Research has not supported biorhythm theory. A 1998 review of 134 studies, published and unpublished, found that 35 reported some support for the theory, but that methodological and statistical errors explained those findings; the other 99 studies found no support. The reviewer concluded that the theory is not valid. The 2026 review notes that the cycles have never been confirmed by experiment and that no physiological mechanism for them has been identified. Kruszelnicki, noting the same lack of support in scientific journals, also asks why the cycles should start exactly at birth and never vary, given that the heart is beating months before birth and that menstrual cycles do vary. Australian researchers reached the same result in sport and in workplace safety (see Australian research below).

Scope

What it includes

• Describing a person's physical, emotional and intellectual capacities in terms of three fixed cycles that start at birth

What it is not

• Biorhythms in this sense are not the same as the biological rhythms studied in the science of chronobiology, such as daily (circadian) rhythms and longer and shorter cycles, which have measurable physiological signs. The word "biorhythm" is still sometimes used loosely in scientific writing for those validated rhythms, which the authors of a 2026 review argue causes confusion.
• Biorhythms are not mediumship. The Spiritualists' National Union describes mediumship as giving evidence that life continues after death, not foretelling events (see Within Spiritualism below).

Traditions and lineage

The term biorhythm was introduced in the early 20th century by Wilhelm Fliess, a German ear, nose and throat specialist and an associate of Sigmund Freud. Fliess proposed the fixed 23-, 28- and 33-day cycles. Biorhythm theory became popular with the general public in the late 1960s. Kruszelnicki gives a slightly different account of the origins: he dates Fliess's work on the numbers 23 and 28 to the late 19th century and says the 33-day intellectual cycle was added in the 1920s by Alfred Teltscher, an engineering professor at the University of Innsbruck. Underwood Dudley's history of numerology, published by the Mathematical Association of America, includes biorhythms among its many examples.

The Encyclopedia of Occultism and Parapsychology offers a third version. It credits Fliess with two cycles and the Austrian engineer Alfred Teltscher with the third, and says that Hermann Swoboda linked the cycles to the date of birth. The idea was popularised in the early 1960s through the writings of George S. Thommen, whose supporters included Bernard Gittelson, and simple devices, both manual and electronic, were developed to make charting easier. The entry describes biorhythms as a popular fad of the 1970s: some doctors tried using them in diagnosis, a Japanese railway company credited them with its accident-free safety record, and several European airlines tested them.

Context

Within Spiritualism

Spiritfold has found no published source linking biorhythms with Spiritualism.

Where biorhythms are used to forecast good and bad days, they fall on the forecasting side of a line that Spiritualist bodies draw clearly. The Spiritualists' National Union in Britain says mediumship exists to give evidence that life continues after death, not to foretell events.

In Australian Spiritualism

Paul Gillen's 1981 study of Spiritualists in Sydney lists "biorhythmic analysis" among the popular kinds of divination that Spiritualists tended to be attracted to, along with astrology, palmistry, tarot and tea-leaf reading, although flower reading was the main form at the church he studied. In a note he describes biorhythmic analysis, as it appeared in some daily newspapers, as a divinatory technique resembling astrology, in which the omen is calculated from the time of birth.

A Spiritualist perspective

Biorhythms have only a passing link with Spiritualism, as the Sydney study above shows, where they appear in a list of popular divination rather than as anything taught in church. A Spiritualist would see them as a separate idea, more like a newspaper horoscope than a spiritual practice, and would not confuse them with mediumship, whose purpose in Spiritualism is to offer evidence that life continues after death.

A teacher would also point to the research summarised above, which has not supported the theory, and would encourage honesty about that. If someone enjoys checking a chart, there is little harm in it. The concern is when a person is made to feel that a "critical day" fixes what will happen to them. Spiritualism teaches personal responsibility, and no chart should take the place of good sense, or of medical advice when someone is unwell.

Biorhythms in Australia

Popularity in the 1970s and 1980s

Biorhythms were promoted and used in Australia in the late 1970s and early 1980s. In June 1979 The Australian Women's Weekly reported that Bernard Gittelson, a promoter of biorhythms arriving from the United States, was visiting Australia to publicise a paperback edition of his book Biorhythm: A Personal Science and a biorhythm computer. The magazine said that on an earlier tour, for the hardback edition, he had appeared in every capital city. In January 1981 the Port Lincoln Times described how biorhythm charts were being used in that South Australian town: a local follower drew up monthly charts for a small fee, staff at several businesses displayed their charts side by side so colleagues could see who was having a critical day, and local shops sold biorhythm calculators and a television game unit that could display a chart.

Australian readers also met a detailed account of biorhythms in two 2013 columns by Karl Kruszelnicki for the Australian Broadcasting Corporation's ABC Science website. He wrote that the theory was popular in the 1970s and 1980s before fading, that by the mid-1970s many video arcades had machines that printed biorhythm charts from a person's birth date, that many newspapers printed a biorhythm chart next to the horoscopes, and that handheld biorhythm calculators were sold. He also described his own informal test in the 1970s: after plotting his cycles for a few months and comparing them with what actually happened, he found hardly any match and gave the theory up.

Australian research

Australian researchers tested biorhythm claims in sport and at work. In January 1979 The Canberra Times reported that Brian Quigley of the University of Queensland had told a sports science meeting that Australian athletes had set records at every stage of their supposed cycles. He gave the examples of the runner Ron Clarke and the sprinter Paul Narracott, who had both broken records on "critical" days as well as on "high" days. Quigley said he had first looked at the theory before the 1976 Montreal Olympics, when the mother of the swimmer Steve Holland asked him about it, and that he had advised her to ignore it. Quigley published a study of Australian track and field records in 1981. In a follow-up study of 700 men's world records in track and field set between 1913 and 1977, he found that records fell in the high, low and critical phases of the cycles about as often as chance would predict, and concluded that, like his earlier Australian study, the results gave no evidence that biorhythms exist or have any effect.

In May 1983 G. Soutar and J. Weaver of the University of Western Australia reported to the congress of the Australian and New Zealand Association for the Advancement of Science, held in Perth, on a study of industrial accidents at a sawmilling company. They examined 1,239 accidents involving 571 employees over the last three months of 1977 and all of 1978, using each injured worker's birth date to work out their critical days. They found no link between critical days and accidents, however critical days were measured, and the pattern of accidents was what would be expected if they occurred at random. A paper by Geoffrey N. Soutar and John R. Weaver titled "Biorhythms and the incidence of industrial accidents" appeared in the Journal of Safety Research later that year.

Safety and good practice

Biorhythm charts have been promoted as a way of foreseeing days when a person is more prone to mistakes, poor coordination or accidents, and a Japanese railway company once credited them with its safety record. Research has not supported their use for this purpose. The Western Australian study of more than 1,200 workplace accidents found no link between accidents and critical days, and Quigley wrote that, like his own studies, most sound published research on sport, accidents and medical data gave no evidence that biorhythms exist or have any effect.

Related modalities

• Astrology
• Numerology
• Tarot

Further reading

• Dudley, Underwood. Numerology, or What Pythagoras Wrought. Mathematical Association of America, 1997.
• Hines, T.M. "Comprehensive review of biorhythm theory". Psychological Reports, 1998.
• Kruszelnicki, Karl S. "Biorhythm numbers don't stack up" and "Biorhythms are so last century, man". ABC Science, 2013. Popular science columns, written from a sceptical point of view.
• Quigley, B.M. "'Biorhythms' and men's track and field world records". Medicine and Science in Sports and Exercise, 1982.
• Soutar, Geoffrey N. and John R. Weaver. "Biorhythms and the incidence of industrial accidents". Journal of Safety Research, 1983.
• Touitou, Y., D. Gubin, B. Mauvieux and C. Touitou. "The biorhythm concept revisited". Chronobiology International, 2026.
• "Biorhythm". Encyclopedia of Occultism and Parapsychology. Gale, via Encyclopedia.com.