If you occasionally, more often then not, find yourself questioning the 'reality' of reality to the point that it makes you anxious or depressed because you can't seem to figure out what is going on, you might want to read this book.
It is rather quite introductory, educational and easy to grasp.

If you know that you're 'derealizing' or experiencing derealization and depersonalization, you will definitely find this book interesting and helpful as a step towards understanding yourself more, the authors do present it in a comforting, non-judgmental manner.

Personally, I would definitely like to study this disorder further.
It does seem like a common affliction, and it also seems like a disorder that is present in not only art but within literary and philosophical geniuses.