It is the descent into fear, nightmares, the underworld, or hell. It is the first half of the hero's journey in the mythical corpus. Orpheus descended to the underworld to bring Eurydice back to the world of the living, Odysseus in the Nekyia descended to Hades, Aeneas descended to the underworld, and all returned.
FROM LIGHT TO DARKNESS
We didn't feel the moment our bodies were abducted; we had abandoned them a while ago. We knew we lived in absolute control of our soul and mind, and we knew even more that, no matter what we did, we could never escape. We were happy losing our freedom."