TW: unreality, derealisation

"Unreality is a blanket term that generally refers to things that are blatantly untrue but are presented as though they were fact, particularly when reality itself is questioned. … 

In people who experience depersonalization, derealization, and other similar mental states, this can cause severe anxiety, because it leads them to question whether what they perceive to be real is actually reality, whether they actually inhabit a physical body, or whether they even exist at all. [x]

Seen in the tropes: Your Mind Makes it Real, All Just a Dream, Or Was it a Dream?