"Biorhythms are inherent cycles which regulate memory, ambition, coordination, endurance, temperament, emotions, and much more. We each have three fundamental biorhythm cycles. Each biorhythm cycle has a particular function, and a particular life cycle."
Physical Cycle - 23 days The physical cycle is said to be the dominant cycle in men. It regulates hand-eye coordination, strength, endurance, sex drive, stamina, initiative, metabolic rate, resistance to, and recovery from illness. Surgery should be avoided on physical transition days and during negative physical cycles.
Emotional Cycle - 28 days The emotional cycle is considered the dominant cycle in women. It regulates emotions, feelings, mood, sensitivity, sensation, sexuality, fantasy, temperament, nerves, reactions, affections and creativity.
Intellectual Cycle - 33 days The intellectual cycle regulates intelligence, logic, mental reaction, alertness, sense of direction, decision-making, judgment, power of deduction, memory, and ambition."
The cycles are similar to the breath. There is a positive and negative polarity. The cycles are usually displayed from -100 to 100 with 0 being the middle.
I've monitored my cycles and environment, emotions, physical energy, etc and concluded that they work like the breath, inhale/exhale. There is a period of introversion, introspection, focusing on the subjecting, learning, listening and then a period of extroversion, expression, focusing on the objective, teaching and socializing.
http://www.degraeve.com/bio.php - here you can generate a free chart.