A biorhythm is a theoretical process by which the human body and mind are regulated according to set patterns. Biorhythms are usually separated into three distinct groups: the emotional, mental, and physical cycles. Classically, the lengths of these cycles are 28 days, 33 days, and 23 days respectively.
Calculating one’s biorhythms is accomplished by dividing the number of days a person has lived by the biorhythm cycle one is calculating. The remainder represents how far into the current cycle one is. Biorhythms are thought to follow a regular wave, oscillating back and forth over the length of the cycle. On the first day of one’s cycle, one is thought to be at an optimal functioning level, while at the low point, a person is viewed as being at his or her worst possible level of functional capability.
The practice of tracking the body’s biorhythm dates back to the end of the 19th century, when a number of doctors began observing what they perceived as repeating cycles in a number of ailments and immune-system weaknesses. The lengths of the biorhythm cycles date from this period and are based on the early observations of these physicians.
Whether or not the protoscience of biorhythms is accurate is a matter of some debate. Although there is scientific evidence for a number of biological cycles — such as the circadian rhythm that regulates our body’s understanding of a day, or a woman’s menstrual cycle — the transition from these known rhythms to a more generalized affective biorhythm is disputed by many scientists. Critics point out that the lengths of the cycles seem to be somewhat arbitrary, that it is highly unlikely that a biorhythm would be the same for all people, that most “evidence” presented is in fact simply anecdotal, and that a number of other key assumptions seem to be taken as leaps of faith rather than based on hard facts.
A number of corporate entities utilize biorhythm factoring to determine when their employees will be at their best and least likely to make mistakes. A number of airlines, for example, have experimented with or currently use biorhythm tracking to indicate the days on which their pilots need to expend extra energy in maintaining concentration and attention, to compensate for an ebb in their biorhythm.
Many software applications exist to help people track their biorhythms, based on their birthdate and the current date. These programs allow users to project forward to see when their optimal days of activity will be — particularly when all three of their cycles line up at a high level of functioning. Some watches, personal digital assistants (PDAs), cell phones, and other portable devices also include rudimentary biorhythm calculators.