Sushupti [deep sleep) is often characterised as the state of ignorance. No. It is the pure state.
There is full awareness in it and total ignorance in the waking state.
It is said to be ajnana ignorance only in relation to the false jnana prevalent in jagrat the waking state).
Really speaking jagrat the waking state) is ajnana ignorance and sushupti [the sleep state) prajna wisdom.
If sushupti is not the real state where does the intense peace come from to the sleeper?
It is everybody’s experience that nothing in jagrat can compare with the bliss and well-being derived from deep sleep, when the mind and the senses are absent.
What does it all mean?
It means that bliss comes only from inside ourselves and that it is most intense when we are free from thoughts and perceptions, which create the world and the body, that is, when we are in our pure being, which is Brahman, the Self.
In other words, the being alone is bliss and the mental superimpositions are ignorance and, therefore, the cause of misery.
That is why samadhi is also described as sushupti in jagrat sleep in the waking state; the blissful pure being which prevails in deep sleep is experienced in jagrat, when the mind and the senses are fully alert but inactive.