Low-Light Vision

Low-Light Vision is a condition $$ It is granted by a few consumables, such as Cateye, Nuka-Cola Quartz and the perk, Friend of the Night.

Limited low-light vision can also be granted by using weapons with the night scope mod attached, such as the Varmint Rifle. It also granted by the hazmat suit.

Behind the scenes
The effect is almost identical to Night-Eye in The Elder Scrolls IV: Oblivion, also made by Bethesda Softworks.