Brightness alteration is a distortion or change in the levels of perceived brightness comprising a person's vision. This usually results in the person's vision becoming darker    and muted, but could also potentially result in it becoming lighter and more vivid   depending on the person's environment and substances they have consumed. Brightness alteration can be accompanied by the coinciding effects of pupil dilation or constriction and photophobia. It is most commonly induced under the influence of moderate dosages of hallucinogenic compounds, such as psychedelics, dissociatives, and deliriants.
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