Shambhavi Mudra
In Sanskrit, Shambhavi means "happiness" and Mudra means "gesture." This practice is a Mana Mudra meaning "head gesture" practice and is described in the Hatha Yoga Pradipika, Gheranda Samhita as well as the Shiva Samhita.
During this practice the eyes can be open or closed. This practice is a path to attaining higher awareness and inducing higher Consciousness within the practitioner.
This practice is considered as a Trataka practice because of the blinkless gazing required by the practice and is also a Meditation practice.
Practice
Sit in a Meditative Asana or a comfortable seated position.
Roll the eyes upward then inward toward Ajna Chakra or between the eye brows.
Release the gaze when the sensation of strain appears.
At the end of the practice, continue to sit and Meditate on the stillness in front of the closed eyes.
The six cleansing actions are intended to be the start of a Yoga practice in order to clean, strengthen, remove toxins and improve the flow of Prana through out the practitioner.
Yoga poses help to elongate and strengthen the muscles of the body as well as to calm the mind for the deeper spiritual practices of Yoga.
Breathing exercises are a great practice to remove carbon dioxide, increase lung capacity as well as being a good preparatory practice for the deepest spiritual practice of Yoga, Meditation.
The four body locks that makes up this practice give the practitioner the ability to hold or lock Prana in certain locations of the body. These practices also allow the practitioner to release blockages that may be holding the practitioner back.
The gestures in this practice include the whole body and are intended to awaken Prana, Chakras as well as Kundalini energy within the practitioner.
Meditation is the highest spiritual practice of Yoga which is why this practice is the most difficult practice to preform, but with correct knowledge and dedication, can be the most profound practice of Yoga.