That’s pretty interesting…
I have developed the tanden method of breathing, where the area around my tanden expands and contracts, with a slight lift of the perineum (root lock). I find that when this happens, my ‘mind’ and energy stays in the hara (abdomen) and does not rise upwards. In other words I don’t get ‘locked up’ in the sensations within the skull but perceive the entire field of experience more evenly, with emphasis on the sensations within the hara.
Hakuin wrote in his Yasenkanna these few passages:
Again it is said:“When the heart is exhausted, in the vacuity fire blazes up; therefore at the time when there is vacuity, take the fiery energy downwards and mingle it with the kidneys—that is the remedy.” It is the way of Fulfilment.
From the mounting of the heart-fire your grievous illness has arisen. If you do not take it down you will never recover, though you learn and practice all the healing remedies human and divine.
"This contemplation attains right contemplation by no- contemplation. Many pointed contemplation is wrong contemplation. Hitherto your contemplation has been many- pointed and so you have contracted this grave malady. Is it not then proper to cure it by no-contemplation? If you now control the fire of heart and will and put it in the Tanden and right down to the soles of the feet, your breast will of itself become cool, without a thought of calculation, without a ripple of passion. This is true contemplation, pure contemplation.