Derealization is an alteration in the perception or experience of the external world so that it seems strange or unreal. It is a dissociative symptom of many conditions, such as psychiatric and neurological disorders, and not a standalone disorder. It is also a transient side effect of acute drug intoxication, sleep deprivation and stress.
The detachment of derealization can be described as a immaterial substance that separates a person from the outside world, such as a sensory fog or a pane of glass. Individuals may complain what they see lacks vividness and emotional colouring. Feelings of déjà vu or jamais vu are common. Familiar places look alien, bizarre, and surreal. These symptoms are common in the population, with a lifetime prevalence of up to 74% and between 31-66% at the time of a traumatic event.
Depersonalization is a subjective experience of unreality in one's sense of self, while derealization is unreality of the outside world. Depersonalization and derealization are often used interchangeably, although evidence suggests they have distinct neurobiological mechanisms. Chronic derealization may be caused by occipital temporal dysfunction.
Derealization can accompany the neurological conditions of epilepsy, migraine, and mild head trauma. There is a similarity between visual hypoemotionality, a reduced emotional response to viewed objects, and derealization. This suggests a disruption of the process by means of which perception becomes emotionally coloured. This qualitative change in perception may lead to the reports of everything viewed being unreal or detached.
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