Quote Originally Posted by Tranquil Toad View Post
I can't imagine why this works, perhaps your tongue has just become an object of concentration. Concentrating on anything will temporarily silence one's mind.

As for why you'd want to do this, as dreamvail mentioned, it makes it easier to wild or to fall asleep, and secondly I think less internal chatter is healthier than a constant stream. Think of the mind like a muscle. Nothing wrong with lifting weights and flexing, but if you do it all the time without rest it destroys the muscles. If thoughts continue unending without rest, they quickly become repetitive, banal and even destructive. Allowing long periods of inner silence will actually increase the quality and creativity of mental activity when it does arise.
Well said, but there's still more: If you can go into your dreams with a mind that is free of clutter, you stand a much better chance of not only successfully holding onto your intentions as you fall asleep, and then entering an LD easily. Also, the quality of your LD might be much greater if you carry an ability to clear your mind's clutter once in the dream. Much greater.