Tongue is touched with soft palate to activate the parasympathetic system that produce saliva, calmness and focused mind concentration. The same phenomenon occur when we are hungry, on fast or eating food. Parasympathetic system remains active under these types of conditions. Strengthened and activated parasympathetic nervous system produces power in the digestive system including the salivation. It also empowers the brain. It also produces the mental calmness, bliss, focused concentration and good judgement. The same system is activated during a romantic love affair that is why mouth becomes watery at those times. Also there is experienced a profound bliss, calmness, brain working and focused concentration. Opposite system is the sympathetic nervous system that is also called as the fight or flight system. It has all the actions as opposite to that of the sympathetic nervous system. It is activated during the stress of any kind, at peak of romance; near, during and after the ejaculation. It depresses appetite, digestive functions and brain functions. Depression is caused by it due to a loss of mindfulness. It damages the body in a severe way by keeping the blood pressure high. By creating mindfulness, Yoga activates the parasympathetic nervous system in an indirect way. This results in an improvement in the appetite and alleviation of the depression. Blood pressure is also improved. Body is rejuvenated and its energy is conserved to fulfill the good purposes in one’s life. The same tactic is employed in the tantric sexual YOGA( Sexual Yoga, a myth or a reality )too. Romantic love affair is sustained for very long without an ejaculation. This results in the sustained and prolonged activation of the parasympathetic nervous system, not allowing the sympathetic nervous system to raise it’s hood up. It results in the quickened spiritual development and growth.
Also, with little practice of touching tongue with soft palate works like an one way valve for kundalini. Through that valve, Kundalini can pass easily downward only, not upward. So Kundalini from tired and confused brain travel to lower chakras mainly naval chakra. That results into stabilization of concentration on Kundalini there without tiredness and confusion of brain. A spiritual relief is immediately regained.