Hesychasm goes back to Mary.
The main characteristics of hesychasm can be enumerated as follows:
1) Entering into a state of quiet without reading or thinking or reasoning or imagining. In this stage hesychasm resembles St. Teresa's prayer of quiet and the early contemplative states described by many mystics.
2) Repeating the Jesus prayer. There are several formulas, one of the most common being, "Lord Jesus, Son of God, have mercy on me a sinner." What matters is the name of Jesus which, when recited with faith and love, has power to move heaven and earth.
3) Regulating the breathing so that it becomes rhythmical and at the same time fixing one's gaze on the heart, the stomach or the navel. The aim is "to let the mind go back into the heart", a process which is called omphaloscopia from the Greek word omphalos meaning navel.
4) Feeling inner warmth which may become like a fire within. Or one may have a vision of divine light, sometimes called "the light of Tabor".
5) The aim of all is deification or theosis.— William Johnston in Mystical Theology: The Science of Love