Nabho Mudra or the sky mudra involves the tongue touching the upper palate and is similar to Kechari mudra. In Sanskrit, the word ‘nabha’ indicates sky and mudra means a gesture. Nabho mudra is mentioned in Gheranda Samhita and is practiced by meditators from various traditions. Nabho mudra is an easy form of Kechari Mudra and can be easily practised by anyone.
In the Gheranda Samhita, Nabho Mudra is described as a practice where the practitioner turns the tongue upwards to meet the palate and then retains the breath. The text says that one can do this during all activities like sitting, walking, etc.
Nabho Mudra is more of a Raja Yoga practice. In Hatha yoga, a similar practice is done called Kechari mudra which involves taking the tongue all the way back to reach the nasal cavity. This is done with lot of effort like milking the tongue and cutting the frenum membrane of the tongue, bit by bit, to make it elongated. Once it reaches the nasal cavity it can be extended to the roof of the cavity. By stimulating certain regions of the cavity with the tongue, the yogi gets to taste a sweet liquid called amrita or nectar. By consuming this nectar the yogi rejuvenates his body and attains long life.
Many masters do not recommend cutting of the frenum membrane of the tongue. They say that the same results can be gained by constantly practicing the Nabho Mudra. It is said that during certain stages of meditation, the tongue automatically goes and touches against the roof of the palate. By constant practice, the tongue can go further back towards the throat, till it touches the uluva at the back. Finally it can be made to enter the nasal cavity. Of course, this takes time and practice. To reach the nasal cavity, it may take many years of practice.
There is a subtle connection between the tongue and the thoughts. Speech is only an expression of our thoughts. Our thoughts precede our speech. So a subtle correlation develops between the mind and our tongue. This basic understanding is exploited during the Nabho mudra. During Nabho mudra the tongue is fixed in one spot touching the palate. It can be observed that when your tongue doesn’t move, then thoughts also get supressed naturally. Thoughts may still occur, but in a supressed way as if there is being throttled. This principle is a great help to meditators. Instead of fighting with your thoughts, just use the Nabho mudra and you will get a substantial help to calm your mind.
There is another aspect to this mudra which is related to the energy flow from the head to the entire body. It is said that the cosmic energy can flow through the Sushumna nadi or the central meridian and nourish the entire body. But unfortunately this flow is broken at the region of the throat. Placing the tongue against the palate is one way to reconnect this broken circuit of cosmic energy.
This free flow of cosmic prana can do wonderful results to the body. It is said in the Gheranda Samhita that by performing Nabho Mudra, the yogi removes all diseases and disorders of the body. The cosmic prana has a wonderful healing effect on the entire system.
The Gheranda Samhita also talks about retaining the breath during this practice. That is only optional during meditation. During meditation, the breath naturally slows down. During deeper states one can experience natural stopping of breath for even few minutes. This is called Kevala kumbhaka. Hence it need not be forced.
Nabho mudra can be done during any time of day and during any light activity (excluding eating, talking and sleeping ofcourse). Hence, Nabho mudra is an excellent tool for all practitioners of meditation.