Unconsciousness, deep sleep, or coma are not devoid of consciousness; they lack memory and awareness. There are mental processes in a suppressed, weakened state. Entry into them occurs without any wisdom.
In contrast, the attainment of Nirodha Samapatti occurs through very acute awareness in Jhana. The mind on this path is extremely sharp and pure, without any suppression. This exceptionally sharp and conscious mind gradually refines and finally extinguishes through tranquility and the wisdom of renunciation. Because the mind is conscious, this cessation is not associated with the loss of awareness and memory but with the cessation of contact through the weakening of attachment to sense objects, by moving from coarser objects to subtler ones. Releasing the coarser and taking the subtler, finally releasing even the subtlest object through tranquility and insight. This release of the subtlest object is the special component that distinguishes Nirodha Samapatti as a transcendent state!
Nibbana is the cessation of contact, the release of acquisitions and objects, the cessation of attachment, the cessation of enchantment and enjoyment with objects and vedanas. Nibbana is fully realized in the process of achieving Nirodha Samapatti because to sever contact, one must destroy attachment to objects and restless passion.
When the mind arises again, it finds no objects and directly perceives the element in which there is no arising, changing, and ceasing—it sees the non-object, animitta. This is the moment of Phala Samapatti, the contemplation of the peace of cessation, Nibbana. It occurs immediately after Nirodha. This is another transcendent, unseen property of Nirodha Samapatti.
Finally, having reached Nirodha, the mind sees the peace and relief it experienced without being bound by the formations and agitation of phenomena. It sees that there is no enduring essence hidden behind the husk of formations. Thus, it deeply understands emptiness and anatta. This is another transcendent and unseen property of Nirodha Samapatti.