Our bodily humors are attuned to the rising and setting of the sun, it is always best to awake before sunrise. Drinking a glass of luke-warm water helps flush out all toxins accumulated overnight in the body.
The last part of the night being ruled by vata involved in the process of elimination early morning is the best time to eliminate the body's physical waste. Proper elimination also helping remove the kapha that naturally accumulates overnight. Defecation once or twice daily is the best.But urination then is wise. Examine your eliminated toxins each morning and if you notice any disturbance indicating poor digestion, go on a fast. It will allow the body rest to correct the system before disease sets in. Never suppress the natural physical urges that are called adharniya vegas in Ayurveda like elimination, hunger, thirst, sleep, sneezing, yawning, vomiting, flatus and ejaculation, for it will lead to discomfort and even disease.
"Promotion of positive Health by positive methods"