From one’s birth on the human being disposes of three types of biorhythm: physical, emotional and intellectual. Each of the biorhythm cycles consists of two half-cycles: a positive and a negative one.
At hand of this application you would be able to watch over your physical, emotional, intellectual and intuitive energy.
Although this theory does not offer a prediction better than the chance itself, it offers an interesting aspect of our life and an attempt to help us plan our activities according to the cycle we undergo.