Depersonalization or depersonalisation (sometimes abbreviated as DP) is the experience of feeling detached from, and as if one is an outside observer of, one's mental processes, body, or actions. (e.g., feeling like one is in a dream; a sense of unreality of self, perceptual alterations; emotional and/or physical numbing; temporal distortions; a sense of unreality).   During this state, the affected person may feel that they are "on autopilot" and that the world has become vague, dreamlike, less real, or lacking in significance. Individuals who experience depersonalization often feel divorced from their own personal physicality by no longer sensing their body sensations, feelings, emotions, and behaviours as belonging to a person or identity.  It is also often claimed by people who have depersonalization that reality seems unreal, distant or hazy. Depersonalization can sometimes be distressing to the user, who may become disoriented by the loss of a sense that their self is the origin of their thoughts and actions. However, it does not have to be an inherently negative altered state of awareness, as it does not directly affect one's emotions or thought patterns. It is perfectly normal for many people to slip into this state temporarily, often without even realizing it. For example, many people often note that they enter a detached state of autopilot during stressful situations or when performing monotonous routine tasks such as driving. It is worth noting that this state of mind is also commonly associated with and occurs alongside a very similar psychological disorder known as derealization. While depersonalization is a subjective experience of unreality in one's sense of self, derealization is a perception of the unreality of the outside world. Depersonalization is often accompanied by other coinciding effects such as anxiety and a very similar psychological disorder known as derealization.  It is most commonly induced under the influence of moderate dosages of dissociative compounds, such as ketamine, PCP, and DXM. However, it can also occur to a lesser extent during the withdrawal symptoms of stimulants and depressants.
In psychology, chronic depersonalization that persists during sobriety for prolonged periods of time is identified as "depersonalization disorder" and is classified by the DSM-IV as a dissociative disorder. While degrees of depersonalization are common and can happen temporarily to anyone who is subject to an anxiety or stress-provoking situation, chronic depersonalization is more common within individuals who have experienced a severe trauma or prolonged stress and anxiety. The symptoms of both chronic derealization and depersonalization are common within the general population, with a lifetime prevalence of up to 26-74% and 31–66% at the time of a traumatic event.  It has also been demonstrated that derealization may be caused by a dysfunction within the brains visual processing centre (occipital lobe) or the temporal lobe, which is used for processing the meaning of sensory input, language comprehension, and emotion association.  Within the context of identity-altering effects, depersonalization can be considered as being at the opposite end of the identity spectrum relative to states of unity and interconnectedness. This is because, during depersonalisation, a person senses and attributes their identity to nothing, giving a sense of having no self. However, during a state of unity and interconnectedness, one senses and attributes their identity to everything, giving a sense that the entirety of existence is their self.
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