Night Person (perk)/Fallout 3

Night Person is a perk in Fallout 3, Fallout: New Vegas, Fallout 4, and Fallout 76.

Fallout 3 and Fallout: New Vegas
With this perk, the player gains +2 to both Intelligence and Perception (up to a maximum of 10) between 6:00 P.M. and 5:59 A.M. in-game time.

As this perk only gives a temporary increase to your statistics (unlike the Intense Training perk), it does not give an advantage when leveling up - there's no change to the number of skill points gained and the increased stats don't count for perk requirements. Thus, the only effects are enhanced threat detection, Intelligence and Perception ability checks (in dialogue and elsewhere), and a bonus of +4 to skills influence by Intelligence and Perception.

Fallout 4
With the first rank of this perk, the player receives an extra +2 points to Intelligence and Perception between the hours of 6:00 p.m. and 6:00 a.m. The second rank raises this bonus to +3 and also gives night vision while sneaking.

With Far Harbor, another rank is added that provides one with 30 extra hit points between 6:00 p.m. and 6:00 a.m.