The theory of biorhythms belongs under the heading of numerology. Or, perhaps it belongs under the heading of astrology.It is based on the notion that the numbers 23, 28 and 33 rule our lives. The theory asserts that at the moment of birth the confluence of these magical numbers determines our daily destiny.
At the moment of birth, according to the theory, three biorhythmic cycles [note1] are set to zero. The first fourth of the first cycle is an ascent, then half of the cycle is in descent, then the last quarter of the first cycle ascends back to the zero line. The three cycles are a 23 day cycle (the physical), a 28 day cycle (the emotional) and a 33 day cycle (the intellectual). The cycles repeat until you die. Therefore, if your birthday is known a chart can be consulted which will tell you exactly where in each cycle your rhythms are on that day. So what, you might say. What difference does it make, you might wonder. Well, according to biorhythm theory devotees, it may make all the difference in the world.
According to the theory, when certain points on the cycles are reached a person may enjoy special strength or suffer special weakness. As you can imagine, when a cycle reaches its zenith, that's good, and when a cycle reaches its nadir, that's bad. But what you might not see so easily is that when cycles cross the zero line on the ascent or descent, these "switch point days" are "critical" days. These are days you want to know about in advance so you can prepare for them. For example, if you are scheduled to take a test that will measure your thinking ability, make sure you do not take the test on a day when your intellectual cycle is at a critical or a low point. (Now you know why you've done so poorly on certain tests. You took them on the wrong day! Of course, don't forget, that the only reason you did well on other tests was because your intellectual cycle was at a peak! If you won't take any blame, remember that you can't take any credit either.) On the other hand, if you are a long distance runner, try to pick your next race date so that you are at a peak on your physical cycle.
The worst day of all, according to the theory, is the "triple critical", the day when all three cycles are at their nadir. Next worse is the "double critical", when two cycles meet at the switch point. As you can imagine, it gets very complicated tracing all these cycles on their ascents, descents, switch points, etc. But it does not take a mathematician to figure out that it is going to be easy to find cases that fit the theory. For example, the physical cycle is 23 days long. That means that every 11.5 days is a physical cycle switch over day, or 31.76 days every year are really bad days for your body. So, the odds of, say, having a heart attack on a given physical switch over day are about 1 in 11. Now, one valid empirical test of the theory would be to collect data on heart attack victims and see if significantly more that 9% (1 out of 11) had their heart attacks on physical switch over days. Instead, the usual evidence given by believers is an anecdote about Clark Gable or someone else who had a heart attack on a switch over day. There are thousands of heart attack victims each year and 1 out of 11 of them would be predicted by chance to have the attack on a switch over day. So, finding several individual cases of people who have serious physical problems on a critical physical day is to be expected, not wowed at. The ho-hum response that anecdotes such as the Clark Gable story should evoke from a reasonable person should put one to sleep when you realize that some biorhythmists count the day before and after a critical day as "half-critical" days as just as bad as critical days. This means that at least once every 8 days, instead of once every 11 days, is a bad day for the body. Worse, 6 out of every 23 days (if you begin counting on the day before a critical and stop counting on the day after the next critical) are danger days for the body. That ups the odds to about 1 in 4. [note2] Again, a meaningful test of the theory might be to study death certificates. If significantly greater than 25% of the sample died on a critical or half-critical day, then you have a scoop. If you find that Bella Lagosi or Belle Starr died on one of these special days, you have nothing out of the ordinary; for 25% of all people will die on one of the dangerous days.
Another typical but useless test of the theory is to keep track of how accurate the theory is by charting each day and keeping a diary of your days. I saw the actress Susan St. James on a television program once where she described how she had done this. She was convinced. If her chart predicted a low emotional day, by golly she was upset that day. If her chart predicted a physical high, by gum she felt great that day. On a day when her intellectual cycle was at a low, oh boy she couldn't think straight about anything. In some circles this is known as the self-fulfilling prophecy; in others it is known as the power of suggestion. But whatever you call it, it ain't science.
James Randi had George Thommen, president of Biorhythm Computers, Inc., and author of Is This Your Day? How Biorhythm Helps You Determine Your Life Cycles, do a biorhythm chart for Randi and his secretary. One of the listeners to Randi's radio program was selected for an experiment. She was to be given her own personal chart and she was to keep a day-by-day diary for two months and to rate her chart for accuracy. She reported that the chart had been "at least ninety percent accurate." Randi had actually sent her his own chart. He told the subject that he had done this by mistake. She agreed to check her diary with her real chart which Randi gave her. She reported that the new chart was even more accurate than the other one. Actually, she'd been given Randi's secretary's chart. This kind of after-the-fact rationalization of data is common among believers in astrology. In fact similar tests of astrological charts have been done, with the same outcome.
Here's a test for you. Reggie Jackson, who was inaugurated into Baseball's Hall of Fame, was born on May 18, 1946. The greatest day in his brilliant career was on October 18, 1977. On that day he hit three consecutive home runs on three consecutive pitches off three different pitchers to help the New York Yankees win the game and the World Series against the Los Angeles Dodgers. The biorhythm theory predicts that Jackson should have been at a physical zenith on that day. Was he? If he was, does that prove the theory? If he wasn't does that disprove it?
You might wonder how such a theory ever got invented. To understand that we have to go back to the nineteenth century and Wilhelm Fliess, a Berlin physician, numerologist and good friend of Sigmund Freud. [note 3] He worked out the 23 and 28 day cycles for health. Fliess was a nose specialist who, along with Dr. Hermann Swoboda, a psychologist and a patient of Freud's, came up with the 23 day `masculine' (physical) cycle and the 28 day `feminine' (emotional) cycle. In the 1920s and engineer named Teltscher added the `intellectual' or `mind' cycle of 33 days.
How did Fliess come up with his theory about the magic of the numbers 23 and 28? He was fascinated by the fact that no matter what number he picked he could figure out a way to express it in a formula with relation to either 23, 28 or both. Martin Gardner writes:
Fliess's basic formula can be written 23x + 28y, where x and y are positive or negative integers. On almost every page Fliess fits this formula to natural phenomena, ranging from the cell to the solar system....He did not realize that if any two positive integers that have no common divisor are substituted for 23 and 28 in his basic formula, it is possible to express any positive integer whatever. Little wonder that the formula could be so readily fitted to natural phenomena! [Gardner pp. 134-135]
My introduction to the science of biorhythms came through my office mate at Sacramento City College. He held a masters degree in psychology and a doctorate in divinity from Harvard. I considered him and his wife (also a believer) to be intelligent people and people of integrity. Dr. G. loaned me Biorhythm--A Personal Science by Bernard Gittleson and the Thommen book mentioned earlier. I read what I could of them and returned them with the comment that the evidence they presented was mainly anecdotal or, what I would call, `stories and statistical numerology'. I was being charitable. When one reads enough in the areas of science and pseudoscience one's `crap detector' [to use Hemingway's term] quickly identifies books written by people who have little understanding or concern for proper empirical investigation or for what counts as good evidence for a hypothesis or for what is a plausible explanation for data gathered. The Gittleson and Thommen books were quickly identified by me as more likely driven by fraud, error, wishful thinking, and incompetence than by objective and proper analysis of data.
One day, I presented Dr. G. with an article I had clipped from the newspaper which reported on a study done by researchers at Johns Hopkins which failed to confirm one of the predictions of biorhythm theory regarding propensity to have accidents on `critical days'. To his credit, Dr. G. read the clipping. But he handed it back to me and with scornful derision said, "Well, what do you expect from people who don't want to believe!"
One of Dr. G.'s favorite proofs for biorhythm theory was his claim that Mark Spitz, who had recently won a phenomenal number of Olympic Gold medals in swimming events, achieved his successes while at biorhythmic peaks! I asked Dr. G. if anyone had checked the charts of all the other winners and losers at the Olympics. He was unimpressed with my question and apparently saw no need for such an investigation. It seemed to me, however, that if there was anything to these biorythmic peaks and criticals that a statistically significant number of winners' charts would resemble Spitz's chart and a statistically significant number of losers would show charts at critical lows. My gut feeling was that any such study, if properly done, would probably show that there was a chance distribution of where anyone's chart lines were on the days they won or lost. But the true believer needs no such test to assure him of the validity of his theory.
Again, to true believers, tests that have not been able confirm the theory are rejected in favor of tests which create new cycles to fit the data or which make correct retrodictions. They reject cases which do not fit their theory by the ad hoc hypothesis that some people are arhythmic some or all of the time. To the skeptic, there is nothing in the literature that indicates that biorhythm theory has any validity and a great deal in the literature which indicates that the theory is false.
There have been several meaningful tests of the theory, all failing to support it.[note 4] One of them dealt with Thommen's claim that he could predict with 95% accuracy the sex of a child by the biorhythms of the mother. If, during conception, the mother's physical (masculine) cycle was at a high point, a boy was likely. If, during conception, the mother's emotional (female) cycle was at a high point, a girl was likely. (I wonder how many couples fell for this and scheduled their sexual relations according to their desire for a boy or girl child?) A study done by W.S. Bainbridge, a professor of sociology at the University of Washington, concluded that using the biorhythm theory your chances of predicting the sex of the child were 50/50, the same as flipping a coin. A defender of the theory suggested to Bainbridge that the cases where the theory was wrong probably included many homosexuals who have indeterminate sex identities. The defender's husband claimed to be an expert in biorhythms and was unable to predict accurately the sexes of the children in Bainbridge's study based on Bainbridge's data. Little wonder.
further reading
Gardner, Martin. Science: Good, Bad and Bogus (Buffalo, N.Y.: Prometheus Books, 1981), ch. 11, "Fliess, Freud, and Biorhythm."
Randi, James. Flim-Flam! (Buffalo, New York: Prometheus Books,1982), ch. 8, "The Great Fliess Fleece."
1. The alleged biorhythmic cycles of this theory have nothing to do with real and well-established biological cycles, such as the menstrual cycle or circadian rhythms. There are several cyclic patterns of changes in physiology or in the activity of living organisms which are 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 circannual 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. Microsoft Bookshelf © 1987 - 1992 Microsoft Corp.
2. During certain 25 day periods you will have nine bad days, the three at the beginning, three in the middle and three at the end. To calculate the odds for the year, assume that the second day of the year is a switch over day. Then there will be seven bad days during the first 23 day cycle [days 1,2,3,12, 13,14 and 23]. There will be 15 full 23 day cycles in every 365 day year. The 2nd through the 15th cycle will have 6 bad days each. The remaining 20 days of the year will have 4 bad days in them. That yields a grand total of 95 dangerous days a year for your physical health, or 26% of the time you are in physical danger.
3. Freud's letters to Fliess were preserved, much to Freud's dismay. They were first published in English as Origins of Psychoanalysis: Letters to Wilhelm Fliess Drafts and Notes, 1887-1902. Edited by Marie Bonaparte, Anna Freud and Ernst Kris, translation by Eric Mosbacher and James Strachey (London: Imago Pub. Co., 1954). A more recent translation by Jeffrey Moussaieff Masson is available: The Complete Letters of Sigmund Freud to Wilhelm Fliess, 1887-1904 (Cambridge, Mass.: Belknap Press of Harvard University Press, 1985). Fliess's masterpiece is entitled The Rhythm of Life: Foundations of an Exact Biology (Leipzig: 1906).
4. Some of these tests are discussed in Randi's Flim- Flam!, ch. 8. He notes that Terry Hines did a review of these studies and published the results in The Skeptical Inquirer, but he doesn't mention what issue. See also Terence Hines, Pseudoscience and the Paranormal (Buffalo, NY: Prometheus Books, 1990).