While doing the postures, your mind should be in half-consciousn ess, which does not mean sleep. It means silence, emptiness, space, which can then be filled with an acute awareness of the sensations given by the posture. You watch yourself from inside. It is a full silence.
B.K.S. IyengarPranayama teaches the aspirant to regulate his breathing and thereby control the mind.
B.K.S. Iyengar