Depersonalization (or depersonalisation) is an anomaly of self-awareness that can occur under the influence of depression, particularly dissociative depression. It consists of a feeling of watching oneself act as I normally would, while having no control over a situation.
I may feel that I am on autopilot and that the world has become vague, dreamlike, less real, or lacking in significance. When I experience depersonalization I feel divorced from my own personal physicality by sensing my body sensations, feelings, emotions and behaviors as not belonging to the same person or identity as normally qualifies as 'myself'. Often when I have experienced depersonalization I have claimed that things seem unreal or hazy during this state.
Chronic depersonalization refers to depersonalization disorder, which is classified by my doctor as a dissociative disorder. This can be a disturbing experience since when I have it I feel that I am living in a dream. Though degrees of depersonalization and derealization can happen to anyone who is subject to temporary anxiety or stress, chronic depersonalization is more related to individuals who have experienced a severe trauma or prolonged stress or anxiety.
Depersonalisation can be considered as the opposite state of mind in comparison to a feeling of unity and interconnectedness. This is because during depersonalisation, my identity is attributed to nothing which gives me a sense of having no self. However, during a state of unity and interconnectedness, my identity is attributed to everything instead of nothing which gives me a sense that the entirety of existence is my self.
A similar experience with its own associated psychological disorder is known as derealization. The difference between these two states is that that depersonalization is a subjective experience of unreality in my sense of self, while derealization is unreality of the outside world.