A: Most DUI arrests occur at night and on weekends. The following is a list of indicators that someone might be DUI at night. The list is based upon research conducted by the National Highway Traffic Administration (NHTSA): Turning with a wide radius Straddling the center of lane marker Almost striking an object or vehicle Weaving Driving on other than designated highway Swerving Going more than 10 mph below the speed limit Stopping for no reason in a traffic lane Following too closely Drifting Running tires on the center or lane marker Braking erratically Driving into opposing or crossing traffic Signaling in a way that doesn't match driving actions (for example, signaling left and then turning right) Slow response to traffic signals Stopping inappropriately (other than in lane) Turning abruptly or illegally Accelerating or decelerating rapidly Driving with the headlights off