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© 1986-2017 Chuck Anderson •
Physical  Emotional  Intellectual

This document provides a brief background of what biorhythm cycles are, how and when they were discovered, and how they can be put to use. There are a number of books on the subject.  Nearly all of the information in this description is from the book "Biorhythms: Is This Your Day?", by George S. Thommen.

Very briefly, biorhythm cycles consist of three natural human cycles; the physical, the emotional (or sensitivity), and the intellectual.  Each cycle has a unique period and therefore the interaction of these cycles constantly varies.  The physical cycle lasts 23 days, the emotional cycles 28 days, and the intellectual 33 days.  They all start at the zero value on the day of birth and begin the positive part of the cycle.  Half way through the cycle they again cross zero and move into the negative part of the cycle.  This cyclic nature is analogous to a wave pattern.

I will provide you with a brief description of what these positive and negative cycles mean and how to use this information to help in planning day to day activities.  You can learn much more about the interpretation of these cycles from other references.  Reading your biorhythms and noting how you feel or respond to certain situations is the best method for understanding them.  Personal experience will teach you the most.

I will also explain how to read the chart that I have prepared for you.  I believe that it will become intuitive as you learn what the biorhythm cycles are.  If you already know how to interpret biorhythms you will find that this graphic representation of your personal biorhythm cycles will be the easiest way to view the interactions of the three cycles and to plan for future events.


The history of biorhythm research is fascinating and enlightening.  Famous scholars have noticed patterns and cycles in nature for as long as the human mind has been observing and analyzing.  Prehistoric peoples recognized the cycles of the heavens and the seasons.  Ptolemy and Pythagoras recognized some of the subtler cycles and patterns in nature.  Astronomers have always recognized the cycles of heavenly bodies, and modern psychology has produced the concept of bio cycles (i.e., the biological clock).

George S.  Thommen quotes Mark Twain in the preface to his book and I include that quote here:

"By the Law of Periodical Repetition, everything which has happened once must happen again and again -- and not capriciously, but at regular periods, and each thing in its own period, not another's, and each obeying its own law .  .  .  the same Nature which delights in periodical repetition in the skies is the Nature which orders the affairs of the earth, Let us not underrate the value of that hint."

Biorhythmic cycles were first discovered in the late 19th and early 20th centuries in Austria and Germany.  At this time a Dr.  Herman Svoboda, a psychologist in Vienna recorded observations of periodicity of various subjects.  His initial research recorded the recurrence of pain and swelling from insect bites, also fevers, illnesses, and heart attacks.  He noticed a pattern with newborn infants refusing to accepting food in a cyclic pattern.  He also noted dreams and those obsessive little melodies that pop into our heads recurring with cyclic regularity.  This led to the discovery of very distinct 23 and 28 day cycles.  He published several papers and books on the subject.

Dr.  Svoboda created a slide rule device that he could use to predict when the days of criticality occurred in these cycles.

At the same time Dr.  William Fliess of Berlin, who was elected president of the Germanic Academy of Sciences in 1910, was tracing the outbreak of illnesses and fever and how some children would seem immune to a sickness, but at a later time would succumb to it.  He also confirmed the existence of 23 and 28 day rhythms amongst his patients.  Through a variety of studies he concluded that there was a connection between biological rhythms and "evolution, the creation of organisms, and life itself."

The 23 day cycle was of the masculine nature or physical condition of humans. The 28 day cycle was of the feminine aspect and influenced one's emotional.

In the 1920's, Alfred Teltscher, a doctor of engineering, and teacher, observed a cyclic fluctuation in the intellectual capabilities of his students in a definite 33 day cycle..  Others overseas and in the United States followed with similar findings of a 33 day "intellectual" cycle.

Many studies done abroad and in the United States during the 1940's and 1950's demonstrated a higher disposition towards accidents and human error that coincided with these biorhythmic cycles.

George S.  Thommen's "Biorhythms .  .  ." provides many more enlightening details of the history of the research and discovery of biorhythmic cycles.  I highly recommend that you read his book.


There are three biorhythmic cycles; the physical (23-days), the emotional (28-days), and the intellectual (33-days).

                    x  x
                 x       x
           +   x           x
              x             x
           | x               x
         0 |x-----------------x-----------------x--
           |                   x               x
                                x             x
           -                     x           x
         day 1                     x       x
                                     x  x
At birth all three cycles begin at zero (day 1) and follow the above pattern. First going in the plus direction (upward), returning to zero (mid cycle), then going in the minus (downward direction), turning around and returning to the day 1 position to begin the cycle again.  During the upward swing that trait has the most energy and is discharging.  The downward swing is the recuperative, recharging cycle.  The critical days are when the cycle crosses the zero point.  That is when the trait is "switching" from the low, recuperating phase to the high, discharging phase (day 1 of the cycle) or when it is "switching" from the high, discharging phase to the low recuperating phase (mid day of the cycle).  On critical days your physical, emotional, or intellectual state is in flux and has a higher degree of instability. 

Since the period of all three cycles are different (23, 28, and 33 days), the interaction of the three cycles overlaid on top of each other is rather complex.  On the day of birth they are all at their day 1 position (at mid-point and moving upwards.  They are not in this exact configuration again for 21,252 days (23 x 28 x 33) or 58 years and 66-68 days (depending on leap years).  (Who says life begins at 40? Looks like its 58 to me.) This 21,252 day cycle is known as a biorhythmic span.  There are 4,327 days on which one or more of the three phases is critical.  That leaves 16,925 days of mixed rhythm or "normal" days.  When more than one cycle is critical it is referred to as double-critical or triple critical.  These multiple critical days are especially unstable.

The physical and emotional cycles seem to have the most influence on one's state of being (disposition to human error or accidents).  Besides, the intellectual cycle is nearly 1 1/2 times as long as the physical cycle and has far fewer days of criticality.  The physical and emotional rhythms start a simultaneous upswing (day 1 of their cycles) every 644 days (23 x 28).  This period is known as the biorhythmic year and is actually about one year and nine months long.


Fliess believed that the physical cycles originate in the muscle tissues or fibers.  The physical cycle is from your masculine inheritance and affects your physical condition.  During the plus side of the cycle (day 2 through day 11) your physical condition is in a charged state and is discharging.  Physical work is easier.  You feel more vigorous and have more vitality.  Your endurance level is higher.  Some doctors abroad believe that days 2 through 9 (in the plus half of the cycle) are the best days to have elective surgery.

During the minus portion of the cycle (day 13 through day 23) your are in a recuperative recharging state and may tire more easily.  This period is conducive to recuperation.  Some athletes, depending on the state of other cycles and factors may have a slump during this time.  Although, a well trained athlete that has not over prepared could succeed at this time.  This is not a "bad" time.  In fact it can be a good time to practice routine physical activities and "recuperate."

Thommen compares the physical cycle to a car battery and generator.  The fully charged battery can spark the ignition to full power.  When the battery has run down the generator switches in to charge the battery back to full power.

The critical points of the physical cycle are at day 1 and day 11 1/2.  You may be more prone to misjudge your physical energy or endurance while switching from one phase to the other.


The emotional cycle governs the nervous system.  It is due to the influence on nerve cells from one's feminine inheritance and affects the level of emotional.  During the high end of the cycle (day 2 to day 14) one is more inclined towards optimism and cheerfulnes.  Creativity, feelings, love and cooperation are favorably influenced.

During the low end of the cycle (day 16 to day 28) your emotions are in a recuperative state.  You are more inclined to be irritable and negative.  The relative high and low of these two phases is definitely influenced by your general temperament.  An excitable person will have a wider swing than a more sedate or calm person.

The critical days are day 1 and day 15.  Insurance and industrial statistician in the US and abroad have noticed a higher percentage of self caused accidents on these days.  Drivers and other people needing to react quickly with sound judgment should be cautious on these days.

There is something interesting about these critical days.  Since the emotional cycle is 28 days long, exactly 4 weeks, day 1 and day 15 always fall on the day of the week that you were born.  Every other week, this day is a critical day in your emotional cycle.  If you don't know what day of the week you were born your biochart can tell you.  Just look at the days when the emotional cycle is on the axis between plus and minus.  Now look at a calendar.  Ta dah, that's the day of the week that you were born.  Every other one will be critical.


The intellectual cycle was not discovered along with the physical and emotional cycle and it does seem to have less prominence than the latter two. Yet, it does have an influence.  The intellectual cycle originates in the brain cells.  Some of Teltscher's associates believed that it was due to secretions of the thyroid gland.

When the intellectual cycle is in its high, plus phase (day 2 to day 16) one is more capable of absorbing new ideas and can think more clearly.  Mental responses are more spontaneous and memory functions well.  This is a good time for creative thought and studying new ideas.

During the low phase (day 18 to day 33) your capacity to think may be reduced. This may be a better time to rehearse and review known concepts.  Practice of things known will facilitate storage into the mind and the sub-conscious.

The critical points are at day 1 and day 16 1/2.  On these days you should put off making important decisions.  If you must then think through your decision very clearly in advance.


Critical days have been described as "full of danger and difficulty." They are days of flux and high instability.  These are not days to fear, but to perhaps be on guard.  Critical days are not days when an accident will occur, but are a time when you will be more accident prone.  Just knowing that this is the case can prevent the accident or error.

Various studies have indicated that the critical period lasts 24 or 48 hours. Most studies, however, point to the critical period as lasting for 24 hours. Therefore the time of birth can be important in determining this period of criticality.  It is most likely a 24 hour period that begins 12 hours before the time of birth and lasts for 12 hours after the time of birth.  This means that if you were born late at night you should consider part of the day after the charted critical day to be critical as well.  Just home in on the time of birth as being the maximum point of criticality.

For all cycles the day 1 critical period begins 12 hours before the time of birth on that day.  For the emotional cycle the mid-cycle critical period begins 12 hours before birth on the 14th day of the cycle.

Note that the mid-cycle critical day for the physical and intellectual cycles (odd number of days - 23, and 33) occur 12 hours after the time of birth on the 11th and 16th days respectively.  Therefore, the critical period begins at the time of birth on the 11th or 16th day and lasts for 24 hours.  The study of biorhythm cycles is not an exact science and the above information is given as a general guideline.  One analysis says that there is a 24 hour period of criticality for all cycles on day 1 and for the sensitivity cycle on day 14, but that is 48 hours centered on day 11 of the physical cycle and day 16 of the intellectual cycle.

(Note: this was written for the text-only chart.)

Reading the chart I have prepared for you should be quite easy.  It can be quite interesting to unfold it on the floor or on a wall and view the entire year looking for points where the cycles coincide or are critical at the same time.

The chart has the calendar dates printed on the top and bottom and the cycles run in between them.  There is an axis running down the middle that represents the critical point of each cycle and there are guide lines to help demark each day.  The cycles themselves are represented by the three curves drawn with the characters "p", "e", and "i" (physical, emotional, and intellectual).  On day 1 each cycle falls exactly on the axis.  On the mid-cycle day it once again crosses the axis.

For the odd numbered cycles (physical and emotional) the character representing that cycle does not fall on the axis at mid-cycle.  That's because they cross the axis at 11 1/2 and 16 1/2 days.  Therefore, critical days at mid cycle for the physical and intellectual cycle are when the cycle's character is one space above the axis one day and one space below it the next.  One look at the chart will simplify this whole discussion and make it seem overly complex, but it is a detail that you might become curious about eventually.

The character "*" is used when two or more cycles are at the same level for that day.  To determine which cycles they are just see which cycles are not represented by their respective character ("p", "e", or "i") on that date.  The coincidence of cycles is only significant when they occur on critical days.  With a quick scan of the middle axis for the whole year you can easily find the double and triple critical days of the year.  Remember that the physical and intellectual cycles will not actually fall on the axis at mid-cycle critical days, but with this graphic representation those days will be easy to spot as well.


Thommen talks about other things in his book, as well.  I do suggest that you read it.  Most of the concepts in this document are taken directly from his book.

In addition to what I have explained he discusses some subtleties in interpreting biorhythm cycles.  One such subtlety is an observed increase of the instability of an emotional critical day when it coincides with the physical cycle being at it's high point.

He also talks about biorhythms and compatibility.  Essentially, the more similar two people's charts are, rising and falling in nearly the same patterns, the more compatible they are.  He also describes a method of determining the sex of an unborn child.


We all have experienced days of joy and days of depression.  For some unknown reason our dispositions can and do change.  Biorhythm cycles can be used to explain some of this and with practice can be used to predict it.  As I said near the beginning of this article, personal observations of your own physical, emotional, and intellectual state and how they coincide with the rise and fall of the cycles on the chart will give you the most insight as to how they should be interpreted.  I have learned the most by looking back at the chart when I haven't looked at it for several days and seeing how critical days and highs and lows have coincided with events from those past days.

The rise and fall of these cycles are relative levels, not absolute.  You can not predict the future with biorhythms, but you can give yourself the advantage of informed judgement.  With practice, your biorhythm cycles will help you to understand your day to day ups and downs and to prepare for them.

I don't want to open a can of cosmic worms here, but I believe that it is a mixture of pure fate and our own rational and emotional choices that rule our destiny.  This chart can only serve to guide in those choices.  It is not a panacea for a perfect life, but an advisor.  The outcome of your day to day activities is, for the most part, in your hands.

Don't sit in and hide on critical days.  Just be prepared to exercise some extra caution.  Perhaps put off an important decision or activity for a day or two.  Knowing that your energy level may be low during a certain period will allow you to be prepared for it.  When you have a choice, say for selecting a time for selective surgery, use the chart to pick what should be an optimum time.  I have climbed 14,000 ft.  mountains during low periods, on critical days and at high periods.  Your biorhythm cycles are not the only factors determining your physical, emotional, and intellectual state at a given time.

Have fun with your chart.  I hope that you are soon able to understand how your biocycles affect you.

© 1986-2017 Chuck Anderson •