Sri Chinmoy: Suppose you find yourself feeling sleepy after thirty or forty minutes of most powerful meditation. At that time, I wish to say, the physical, vital and mental are not operating in you, but your inner being is operating most powerfully. Mentally you feel that you are not in this world and that you have to come back and be very dynamic. But no! At that time the soul is operating most powerfully.
Again, if you feel that you have been sleeping for half an hour, then naturally you are not meditating. If you are enjoying that kind of sleep, then try to repeat the name of the Supreme as fast as possible. It is not a race, but see how many times you can repeat "Supreme" with each breath. Then, when you feel the power inside the repetition of this name, your whole being will be inundated with divine energy and you are bound to feel a new flow of life and energy. If you repeat "Supreme" that way for five minutes, you will not fall asleep. Your utterance will enter into you as energy. Others may think that you are doing something abnormal, but you are doing the right thing. You may also shake your arms, and stretch your legs. But if you repeat "Supreme" in silence, then you are bound to become very dynamic.