Editing Biorhythm (pseudoscience) (section)

==History==
The 23- and 28-day rhythms used by biorhythmists were first devised in the late 19th century by [[Wilhelm Fliess]], a Berlin physician and friend of [[Sigmund Freud]]. Fliess believed that he observed regularities at 23- and 28-day intervals in a number of phenomena, including births and deaths. He labeled the 23-day rhythm "male" and the 28-day rhythm "female", matching the menstrual cycle.

In 1904, Viennese psychology professor Hermann Swoboda came to similar conclusions. Alfred Teltscher, professor of engineering at the University of Innsbruck, developed Swoboda's work and suggested that his students' good and bad days followed a rhythmic pattern; he believed that the brain's ability to absorb, mental ability, and alertness ran in 33-day cycles.<ref name="skepdic.com"/> One of the first academic researchers of biorhythms was [[Estonia]]n-born [[Nikolai Pärna]], who published a book in German called ''Rhythm, Life and Creation'' in 1923.

The practice of consulting biorhythms was popularized in the 1970s by a series of books by [[Bernard Gittelson]], including ''Biorhythm—A Personal Science'', ''Biorhythm Charts of the Famous and Infamous'', and ''Biorhythm Sports Forecasting''. Gittelson's company, Biorhythm Computers, Inc., made a business selling personal biorhythm charts and calculators, but his ability to predict sporting events was not substantiated.<ref>Hoffmann, Frank W., and William G. Bailey, ''Mind and Society Fads'', 1992.</ref>

Charting biorhythms for personal use was popular in the [[United States]] during the 1970s; many places (especially [[video arcade]]s and amusement areas) had a biorhythm machine that provided charts upon entry of date of birth. Biorhythm programs were a common application on [[personal computer]]s; and in the late 1970s, there were also handheld biorhythm calculators on the market, the ''Kosmos 1'' and the [[Casio]] ''Biolator''.<ref>{{Cite web|url=http://www.vintage-technology.info/pages/calculators/k/kosmos1.htm|title=Kosmos 1 Biorhythm |website=Vintage Technology |archiveurl=https://web.archive.org/web/20120706174117/https://www.vintage-technology.info/pages/calculators/k/kosmos1.htm |archivedate=6 July 2012}}</ref><ref>{{Cite web | url=http://mycalcdb.free.fr/main.php?l=0&id=326 | title=MyCalcDB : Calculator Casio BIOLATOR aka H-801}}</ref>

<gallery mode=packed heights=200>
File:Vintage Kosmos 1 Biorhythm Computer And Calculator, 8 Digits, Green Fluorescent, Calculates A Person's Three Biorhythm Cycles (Physical, Emotional, and Intellectual), Made In Japan, Circa 1977 (23428675179).jpg|Kosmos 1
File:Vintage Casio Biolator Pocket LED Calculator, Model H-801, Made in Japan, Circa 1975 (9273200144).jpg|Casio Biolator
File:Vintage Biomate Handheld Biorhythm Calculator, Certified by the Japan Biorhythm Association, Circa 1970s (11574465133).jpg|Japanese ''Biomate'' biorhythm calculator
</gallery>