Nissan Altima (L33) 2013-2018 Owners Manual ≻ Pre-driving checks and adjustments ≻ Mirrors ≻ Rearview mirror (if so equipped)
Nissan Altima (L33) 2013-2018 Owners Manual: Rearview mirror (if so equipped)

The night position 1 reduces glare from the headlights of vehicles behind you at night.
Use the day position 2 when driving in daylight hours.
WARNING
Use the night position only when necessary, because it reduces rear view clarity.

Mirrors
Automatic anti-glare rearview mirror (if so equipped)