Biorhythms

What is abiorhythm?

A biorhythm is a cycle that a person is said to move through on a fixed period, counted from the day they were born. The theory names three. Here is what it claims, how a day is read, and what the studies found.

Physical
23
Emotional
28
Intellectual
33

Three stepped tracks, one for each cycle, drawn from the day of birth to day 70: they begin together and drift out of step, and they will not begin a day together again for 21,252 days.

The count begins

On the day you were born, three counts started.

Day1of life

Each cycle starts at the same moment, and each is counted in whole days from here.

  • Physical, 23 days
  • Emotional, 28 days
  • Intellectual, 33 days

The idea

The idea

Biorhythm theory holds that three cycles start on the day you are born and repeat, unchanged, for the rest of your life. Each has its own length. Because the lengths differ, the three drift apart and line up again only every 21,252 days, so the combination on any given day is, for practical purposes, yours alone.

21,252

days before all three begin a day together again

Each cycle has its own page: the physical cycle, the emotional cycle and the intellectual cycle.

23days

Physical

Energy, strength, endurance and physical resilience.

Physical, 23 days
The physical cycle

28days

Emotional

Confidence, mood, creativity and emotional steadiness.

Emotional, 28 days
The emotional cycle
  1. Critical, turning upc
  2. Charging+
  3. Full chargeH
  4. Charged, easing#
  5. Critical, turning downC
  6. Depleting-
  7. Lowest chargeL
  8. Recharging*
One lap of the emotional cycle, 28 days: above the line, on it, below it, and back.

Reading the position

How a day is read

The traditional picture is a wave that rises above a midline for the first half of the cycle and falls below it for the second. The first half is read as the high phase, the second as the low, and the two days on which the wave crosses the line are the critical days, when the cycle changes direction.

BioCalendar counts whole days and divides each cycle into eight states: the two critical days, the high and the low, and the four quarters between them. Each state has a symbol, and the three symbols for a date choose one of 512 written readings. How to read a biorhythm chart shows the symbols and the day tables.

Crossing the midline

Critical days

A critical day is the day a cycle crosses its midline. The theory reads it as unsettled rather than bad: a day to notice how you feel. When two or three cycles cross on the same day, the theory calls it a double or triple critical day, which is rare. Critical days, explained.

What the evidence says

The theory has been tested, and the tests did not support it.

  1. 01Accidents
  2. 02Sport
  3. 03Exam marks
  4. 04Deaths

134 studies, reviewed in 1998.

Studies through the 1970s and 1980s looked for the cycles in accidents, sporting results, exam marks and deaths and found no effect; a 1998 review of 134 studies concluded the theory is not valid. We set out the research on Are biorhythms real?. We think you should know this before you download anything.

Why people use it anyway

Because a pattern counted from your own birth date is a good prompt.

Reading where the cycles sit, and then asking yourself whether the day feels like that, is a small daily act of attention, in the way that writing a line in a journal is. Many people find that the value is in the asking. That is how BioCalendar frames every reading: as something to reflect on, never as a forecast, and never as medical, financial or safety advice.

A prompt, not a prediction

  1. 01Read where the cycles sit
  2. 02Notice how the day feels
  3. 03Write one honest line

For reflection only — never medical, financial or safety advice.

The record

Where it came from

Two doctors in the 1890s, a third cycle in the 1920s, a craze in the 1970s. A brief history of biorhythm.

Continue the story

Keep going

  1. 01Are biorhythms real?What the studies found when they tested biorhythm theory against accidents, sport, exams and deaths, why people use it anyway, and how we frame it.
  2. 02How to read a biorhythm chartThe three cycles, the eight states each passes through, the symbols BioCalendar uses for them, and what a critical day, a high and a low mean on the chart.
  3. 03How to calculate a biorhythmWork out a biorhythm by hand: count the days since birth, divide by 23, 28 and 33, and read the state. A worked example, and the formula for a spreadsheet.
  4. 04Biorhythm glossaryThe words and symbols on a biorhythm chart, defined: the three cycles, the eight states and their days, critical days, the midline and the BioRating.
  5. 05Biorhythm vs circadian rhythmA circadian rhythm is a measured body clock of about 24 hours, reset by daylight each morning. A biorhythm is a cycle counted from birth. How they differ.
  6. 06Biorhythm vs astrologyBiorhythms and astrology both read a day from your birth, and neither held up when tested. What they share, where they differ, and how we use one of them.