The Night Vision Effect you're gaining from the Night Person Perk is bugged somehow. It doesn't activate/deactivate when you crouch/stand up. Instead you have to open and close Pipboy to activate/deactivate it.

So instead of just crouching to activate the effect i have to crouch and then open & close pipboy.
And instead of just standing up to deactivate it I have to stand up and then open & close the pipboy.