Question 1

What is a biorhythm?

Accepted Answer

Biorhythm theory proposes that human life is influenced by three (or more) rhythmic biological cycles starting at birth: a 23-day Physical cycle (strength, stamina, coordination), a 28-day Emotional cycle (mood, sensitivity, creativity), and a 33-day Intellectual cycle (alertness, memory, logic). Each cycle is modeled as a sine wave that swings between +100% (peak) and −100% (low), with critical days occurring when the wave crosses zero.

Question 2

What is a critical day?

Accepted Answer

A critical day happens when a biorhythm cycle crosses the zero line (its value is near 0%). The theory suggests these are unstable days — your body is adjusting between a high and low phase, so accidents, mood swings, or sudden mistakes are statistically more likely. Many users avoid scheduling surgery, big presentations, or risky sports on critical days.

Question 3

Are biorhythms scientifically proven?

Accepted Answer

Biorhythm theory is a pseudoscientific model — it has not been validated by peer-reviewed studies. That said, millions of people use it as a fun self-awareness tool, similar to horoscopes. The cycles are easy to compute and the chart is visually compelling, which is why this tool remains popular.

Question 4

Can I see cycles beyond the standard three?

Accepted Answer

Yes. The calculator also visualizes three secondary cycles: Spiritual (53 days), Intuitive (38 days), and Aesthetic (43 days). You can toggle them in the settings to keep the chart focused on the classic trio, or expand it to see all six at once.