Friend of the Night

 is a perk in Fallout: New Vegas.

Effects
You are a true friend of the night. Your eyes adapt quickly to low-light conditions indoors and when darkness falls across the post-nuclear wasteland.

This perk causes a noticeable increase in brightness at nighttime and shortly after entering any area with visibility. The effect is not a gradual one, and its presence can be recognized by a colored tint on the game world reflecting the dominant color of your surroundings (most often light blue when outdoors).

Trivia

 * The blue-tinted nightvision is similar to the visual effect caused the Night-Eye spells in Bethesda's Oblivion.