The two limbs of pratyahara are awareness and relaxation. Though relaxation begins with muscular and physical relaxation, this physical awareness also relaxes the brain.
All your body parts are represented in the brain, and that structure is called homunculus. If you see a picture of the homunculus, you will find that all the different parts of the body have a specific center in the brain.
The thumb covers the largest area along with other extremities such as the feet and toes. Other body parts have a comparatively smaller representation in the brain.
When you are relaxing the body by relaxing different body parts, for example, the right hand thumb, this feeling of relaxation also travels up to the area of the homunculus which is controlling the thumb experience.
Therefore, while you experience relaxation in the thumb, the corresponding centre of the brain also relaxes. When you have covered the entire body, the entire cortex of the brain is relaxed. Due to this, you experience the mind moving into a drowsy state.

If the brain centres remain active, you will not be drowsy. This state of drowsiness is what Sri Swamiji says is the subconscious mind, where you are neither awake nor asleep. In this state you can perfect pratyahara, find the balance between the sensorial and the mental.
Relaxation in pratyahara is engaging relaxation, it is not passive relaxation. The mind is constantly guided, “Visualize this, feel this, move there, move here, do this, do that.” Every instruction is to engage the mind. When you follow the instructions you engage the mind, you do not let the mind wander free.
By engaging the mind in a specific activity you pull together the resources, the shakti, the power, from being dissipated and distracted. When the energies are focused and gathered, relaxation is experienced. When energies are dissipated, stress is created.
Therefore, the yogic concept of relaxation is a dynamic relaxation, it is not sleep or passive relaxation. So, awareness and relaxation represent the two arms of pratyahara.
18 September 2018, Ganga Darshan Vishwa Yogapeeth
From the book “Raja Yoga Yatra 3, Practical Pratyahara”, pg. 33-34, Sw. Niranjanananda Saraswati






