Samadhi

The 4-7-8 rests on a single principle: the exhale lasts twice as long as the inhale. A lengthened exhale favours the shift toward parasympathetic activity, and that is the best established mechanism behind every breathing technique. The exact count matters less than the ratio.

Empty retention, which the yogic tradition calls Kevala Kumbhaka once it settles in on its own, extends the cycle with a pause on empty lungs. It is where inner chatter falls silent most readily, and also the most physiologically demanding part. It should not be attempted before the simple cycle feels comfortable.

The micro pattern lands exactly on 90 seconds. It has no contemplative ambition: it exists to clear the buffer between two calls, two tasks, two decisions. A reset, not a sitting.

A ladder gives an order, it does not give a schedule. Nobody honest will tell you how long separates Savitarka from Nirvikalpa, and the traditions do not even agree on the carving: classical Yoga separates pure consciousness from mental matter, Buddhism denies there is any permanent consciousness to separate, Advaita sees nothing to separate at all. Three maps of the same territory, drawn by people who did not see the same thing there.

It also says nothing about what the measurements are worth. The claim that samadhi is a deactivation of the default mode network coupled with gamma waves travels widely, and it goes further than the data: the studies that measured those effects concerned named practices and trained practitioners, never Patanjali's degrees of absorption. The study details, their actual populations, and the three traps that look like progress are in the long-form article.