How are you?

For people who wants to know if they have a good or a bad day, in beginning of the 20th century, the Austrian psychologist Hermann Swoboda and the Berliner doctor Wilhelm Fliess brought the idea of the biorhythms into being. The biorhythm is a scientifical unconfirmed theory that claims that one's life is affected by rhythmic biological cycles and therefore can be calculated. These inherent rhythms are classically composed of three cyclic rhythms: the physical with a duration of 23 days, the emotional (28 days), and the mental (33 days). The biorhythm became popular in the eighties, when due to the first programmable calculatores and personal computers, it was possible to easy calculate it yourself.
Already in 1965, Certina brought the Biostar to market. The first (and as far as I know only) wristwatch from which you can read your biorhythm.

The Biostar (reference 7301 050) had the manual movement 28-163 inside, which was a derivate of the 28-161 with a additional Biorhythm mechanism. After that, in the Biostar Electric which was provided from 1971, a ESA 9154 Dynotron was mounted, which Certina equipped with a additional "Biomechanism" too. This movement had the designation 28-353. This model was presented first in 1971 in Basel at the "MUBA" fair.
All Biostar models first must be adjusted to the birth date of the owner. For that you have to open the watch and synchronise the cycle discs with the aid of the setting values. If that is exactly what you want to do, here are the appropriate instructions.
The setting values could be requested at the Biorhytmik AG in Basel, Switzerland for example. There you could also request documents about the Biorhythm theory and some "Biomaps". The date of birth could be carved into a field inside of the caseback. There was also a pocket watch version of the Biostar Electric available (Ref. 7501 050).

Well, it seems that the idea of the Biorhythm has not enforced, and so in the middle of the 70s, this in my humble opinion interesting complication disappeared from the picture.

• Hartmut Wynen Technical Informations about the Biostar from Hartmut Wynen (german)
• Biorhythmus-Rechner Calculate your biorhythm