Derealization is defined as the sense or perception of the world as somehow faded, far away, and unreal.
This feeling can be brought about by a variety of events and / or conditions:
Derealization is sometimes categorized together with depersonalization, a notion held by a person that
they are somehow not real. One might even argue that the difference between the states of depersonalization
and derealization is trivial; after all, in each state there is a distinct mental rift between what is and is
not the self.
Some individuals actively seek out a sense of derealization, believing it to be a state in which the
true nature of the universe (arbitrary, meaningless unless we give it meaning) can be clearly observed. If
such individuals are successful, their derealization might lack the element of fear that marks the
experiences of those who are unwillingly thrust into a world that is as translucent and elusive as a fading
dream.
Derealization due to panic and / or trauma is quite unpleasant for the sufferer. The person knows that
he / she exists (obviously someone has to be feeling the fear!) but is doubtful that the collective reality
of others is accessible to them. They feel as if things could just crumble into dusty nothingness at any
moment. Life seems precarious all the time; these people walk on eggshells around their own existence.
This sort of derealization has been treated with varying success rates. Drugs that seek to minimize
anxiety, such as SSRIs or benzodiazepines are often employed, with the hope that treating the underlying
cause (excessive anxiety) will in turn bring the person back to a sense that the world is, indeed, real.
Some rather frightening visual disturbances can occur with advanced or severe derealization. The sufferer
might perceive objects to be fuzzy-edged, shimmery, or spatially distorted. Colors may seem to shift in hue,
and shadows take on a life of their own. This, to me, sounds rather like the effects of hallucinogenic drugs
such as LSD. It makes sense them that perhaps derealization represents a profound change in brain
chemistry from the norm.
Changes in time perception are also common in derealization. Time can seem to slow down and speed up
at random, more so than it does for the "normal" individual. Sometimes it may even seem that there is a
delay between an event happening and the derealized individual's perception of the event. This phenomenon
may be frightening and disconcerting, but it also offers a unique window into the subjectivity of human
experience of time.
Overall, derealization's effect on a person depends largely on the severity of the episode and on the
person's frame of mind. It can be an enlightening experience or a frightening one, but it is certainly
indicative of the great complexity and strangeness of the human mind.
Reference: http://culture.st-and.ac.uk:16080/artsci/cavan/unreal/psycho.htm