The doshas show costant shift inside the body and rhythmic fluctuations are the rule of the nature. Although ideally a balance state of the doshas is necessary for health and happiness, at no time will your doshas be in perfect equilibrium. They will always flow in tune with your age, the time of the day or night, the time of the digestive function and the seasons of the year. In childhood the kapha is dominant .When you reach in middle age it is the pitta that dominates, while in old age vata will be the dominant dosha.The way in which your doshas fluctuate according to the time of the day follows a pattern. Kapha dosha dominates in the morning (between 6 and 10 am) and pitta dominates in the late evening (2to 6 pm) and vatta dominates in the late evening .Similarly cycle are also repeated at night .Seasonal fluctuation in the doshas also adhere to a particular pattern. In the rainy season vata dominates, during the winter pitta dominates; and in early summer kapha dominates. In this way the doshas maintain our regular biorhythms, There by maintaining a balance within us. The biological clock is regulated by the doshic biorhythm and is essential for sustaining life.