Depersonalization is a dissociative phenomenon characterized by a subjective feeling of detachment from oneself, manifesting as a sense of disconnection from one's thoughts, emotions, sensations, or actions, and often accompanied by a feeling of observing oneself from an external perspective.[1][2] Subjects perceive that the world has become vague, dreamlike, surreal, or strange, leading to a diminished sense of individuality or identity. Those affected often feel as though they are observing the world from a distance,[3] as if separated by a barrier "behind glass".[2]

They maintain insight into the subjective nature of their experience, recognizing that it pertains to their own perception rather than altering objective reality. This distinction between subjective experience and objective reality distinguishes depersonalization from delusions, where individuals firmly believe in false perceptions as genuine truths. Depersonalization is also distinct from derealization, which involves a sense of detachment from the external world rather than from oneself.

Derealization is an alteration in the perception of the external world, causing those with the condition to perceive it as unreal, distant, distorted, or in other ways falsified. Other symptoms include feeling as if one's environment lacks spontaneity, emotional coloring, and depth.[1] Described as "Experiences of unreality or detachment with respect to surroundings (e.g., individuals or objects are experienced as unreal, dreamlike, foggy, lifeless or visually distorted") in the DSM-5, it is a dissociative symptom that may appear in moments of severe stress.

I experienced derealization following my first ever anxiety attack. I haven’t experienced derealization for several months now knock on wood but it really is a traumatic thing to go through. It feels like you’re going crazy—even though you know you’re not—and losing touch with reality. The world around you doesn’t feel real and people look strange, almost frightening, and this can give some people a sense of existential loneliness. It’s just really scary and I wouldn’t want anyone I care about to go through what I did. It’s as if you just teleported into a different universe, like puppet world, where people are made of rubber and objects are made out of paper or cardboard. Even though it’s obvious that nothing has changed and the world is still like the same, you can’t help but feel that everything looks artificial.