Nirodha samapatti is a special attainment pertaining to Anagamis & Arahants among Arya disciples. It is also called saññā- vedayita-nirodha , ceasing of feeling and perception’, is the temporary suspension of all consciousness (citta) and mental activity (Citta vithi), following immediately upon the semi-conscious state called ‘sphere of neither- perception-nor-non- perception’ (Newasanna nasannayatana jhana, its the last of the formless/ Arupavacara jhana). The absolutely necessary pre- conditions to its attainment are said to be perfect mastery of all the 8 absorptions (Rupavacara & Arupavacara jhāna) as well as the previous attainment of Anāgāmi or Arahatship.
According to Vissuddi Magga, the entering into this state takes place in the following way: by means of mental tranquillity (samatha) and insight (vipassanā) meditation. one has to pass through all the 8 absorptions one after the other up to the sphere of neither-perception- nor-non-perception (8th Jhana) and then one has to bring this state to an end. According to the Vissuddi Magga, the disciple Anāgāmi or Arahant passes through the absorption merely by means of tranquillity, concentration, he will only attain the sphere of neither- perception-nor-non- perception, and then come to a standstill; if, on the other hand, he proceeds only with insight, he will reach the fruition phala of Anāgāmi or Arahatship. He, however, who by means of both abilities has risen from absorption to absorption and, having made the necessary preparations, brings the sphere of neither- perception-nor-non- perception to an end, such a one reaches the state of ceasing.
Whilst the disciple is passing through the 8 absorptions, he each time emerges from the absorptionattained, and regards with his insight all the mental phenomena constituting that special absorption, as impermanent, miserable and impersonal. Then he again enters the next higher absorption, and thus, after each absorption practising insight, he at last reaches the state of neither-perception- nor-non-perception, and thereafter the full ceasing. This state, according to the Vissuddi Magga Commentary, may last for 7 days and one who wishes to attain this stage first see whether they have life expectancy for seven days and then make a strong determination for not being harm to the body for seven days period. With regard to the difference existing between the Bhikkhu abiding in this state of ceasing on the one hand, and a dead person on the other hand, In him who is dead, and whose life has come to an end, the bodily in-and- outbreathing, verbal thought- conception and discursive thinking, and mental functions like sankhāra become suspended and come to a standstill, life is exhausted, the vital heat extinguished, the abilities are destroyed. Also in the Bhikkhu who has reached ‘ceasing of perception and feeling’ saññā-vedayita- nirodha the bodily, verbal and mental functions have been suspended and come to a standstill, but life is not exhausted, the vital heat not extinguished, and the abilities are not destroyed.
May all beings be well and happy & attain the fruits of Nibbana.