[emotional detachment] is a means of dealing with anxiety by preventing certain situations that trigger it.
Subjects feel they have changed, and the world has become vague, dreamlike, less real, or lacking in significance. It can be a disturbing experience, since many feel that, indeed, they are living in a 'dream.'
Often a person who has experienced depersonalization claims that things seem unreal or hazy. Also, a recognition of self breaks down (hence the name). Depersonalization can result in very high anxiety levels, which further increase these perceptions.
"During episodic and continuous depersonalization, sufferers are able to distinguish between reality and fantasy, and their grasp on reality remains stable at all times