Night Person (trait)

Night Person is a Fallout and Fallout Tactics trait. It does not appear in Fallout 2.

Fallout and Fallout Tactics
You get a -1 modifier to both Intelligence and Perception from the hours of 6:01 AM to 6:00 PM. You get a +1 modifier to these statistics from the hours of 6:00 PM to 6:00 AM.

J.E. Sawyer's Fallout RPG
When performing actions at night (6 p.m. to 6 a.m.), you do things better. During the day, however... It has nothing to do with the level of light, just the time of day. You're not a morning person. +2 to all skill checks at night, -2 to all skill checks in daytime.