when should we wake up in morning early or very early or late ???

Sleep has been shown to be more benificial than excercise alone. Sleep mimics excericse in that it increases insulin sensitivity, releases Human Growth Hormone, and lowers cortisol. In this respect it is essential for a healthy metabolism and staving off metabolic disorders. it is good for an adult to sleep 7.5 to 8 hours if possible. However, keep in mind that sleep much MORE or even much LESS than this amount is associated with more fatility rates. That being said, nothing is better than a full night of sleep. In my opinion, nothing is better than a full night of sleep even if you have to wake up late. Sleep is important for us, never regard it as a waste of time.