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Biorhythms are a theory born in the late 19th century, according to which human life would be governed by three regular internal cycles: the physical cycle of 23 days, the emotional cycle of 28 days, and the intellectual cycle of 33 days. All would start at zero on the day of birth and then oscillate between a positive and a negative phase. Our calculator places your three curves on the date of your choice. Note that this theory remains popular but is not recognized by contemporary science.
The theory of biorhythms was formulated in the late 19th century by the Berlin physician Wilhelm Fliess (1858-1928), a close associate of Sigmund Freud, who proposed two biological cycles of 23 and 28 days. The Austrian psychologist Hermann Swoboda (1873-1963) systematized these ideas, and the engineer Alfred Teltscher added a third intellectual cycle of 33 days in the 1920s. According to this doctrine, each cycle begins at birth and alternates a high phase and a low phase, crossing a critical point at the zero passage. Very fashionable in the 1970s, the theory has never received solid scientific validation.
To obtain your curves, enter your date of birth and the target date for which you want to know the state of your three cycles. The time and place of birth are not needed: the biorhythm theory only takes into account the exact number of days elapsed since birth. The tool computes for each cycle the corresponding sinusoidal value: positive in the energy phase, negative in the recovery phase, zero on so-called critical days. Three overlaid curves let you visualize their evolution over the chosen period.
Treat biorhythms as a symbolic tracking game rather than a biological law. The so-called critical days, where a curve crosses zero, are, according to the theory, moments of instability where attention is recommended. Comparing several cycles can give a qualitative read of a period. Avoid any important decision based on a biorhythm alone: no rigorous study has confirmed the predictive validity of these curves. Better to use them as an introspection tool, comparable to a personal journal.
No. Systematic reviews published since the 1970s, especially Terence Hines's in 1979, have found no reliable correlation between biorhythmic phases and performance, accidents, or health states. The theory is considered by the scientific community as a pseudoscience on the same footing as numerology.
The physical cycle of 23 days would describe the body's energy, resistance, and vitality. The emotional cycle of 28 days would be tied to mood, sensitivity, and intuition. The intellectual cycle of 33 days would touch memory, concentration, and logical analysis. Some authors add secondary cycles, but these additions remain marginal.
According to the theory, a critical day occurs when a curve crosses the zero axis, rising or falling. The cycle concerned would then be unstable, prone to unexpected variations. No objective measure has confirmed these effects, but the idea retains a cultural usefulness comparable to that of "hard Mondays" in common speech.
No, unlike astrology. Biorhythms rest only on the number of days elapsed since birth. Two people born on the same day, in different places and at different times, will have identical curves. Only the date of birth matters.