|"Dissociation" by Joe Z via Flickr|
Any of the quotations I use in this post will be from the book I did the majority of my research with. It has the very succinct and completely easy to remember title: "Overcoming depersonalization & feelings of unreality - A self-help guide using Cognitive Behavioural Techniques."
Depersonalization, derealisation or dissociation are all terms for a similar phenomenon that can be triggered by intense stress or fear, and is also a symptom of many mental illnesses like depression, OCD, anxiety disorders, agoraphobia, or bipolar disorder to name a few. This is not the same as a complete loss of reality, as someone with a form of psychosis would experience, but a feeling of being separate from reality, floating above it or standing to the side of it. It is also not the same as full-blown delusions or hallucination, because the person afflicted is still aware of the fact that these happenings are abnormal. It's not something that can normally be observed from the outside, as no physical symptoms are ever really displayed.
The definition from the American handbook of Psychiatric conditions (version iv 1994) is as follows:
"An alteration in the perception or experience of the self so that one feels detached from, and as if one is an outside observer of one's mental processes or body (e.g. Feeling like one is in a dream)"
The idea of depersonalization has been appearing in medical books and articles since around the nineteenth century, and in fact a lot of the work done on understanding depersonalization has been done in the Maudsley Hospital in my very own London.
Extensive research has helped to debunk some misconceptions about the disorder, for example it was once thought that depersonalisation was a precursor to psychosis. However, this is not the case and while there are rare cases there is no proven correlation between the two.
It has also helped to identify some high-stress situations that would lead to something like depersonalization or a feeling of unreality, but are not necessarily indicative of other mental health problems. Bereavement, neurological conditions like migraines or epilepsy, severe stress, and even jet lag can all trigger depersonalization in some people.