When driving at night, what is the appropriate action upon dimming headlights from high to low?

When you dim your headlights from high to low while driving at night, the appropriate action is to slow down. The rationale for this is that transitioning from high beams, which provide a broader field of vision and illuminate the road more effectively, to low beams can significantly reduce your visibility. This reduction happens because low beams have a narrower focus and are designed primarily for use in oncoming traffic to prevent blinding other drivers.

Slowing down is a prudent choice that allows time to adjust to the reduced lighting conditions and enhances safety. It gives you an opportunity to better assess your surroundings, especially if there are pedestrians, cyclists, or unexpected obstacles on the road. Maintaining the same speed could lead to potential hazards that might not be visible due to the decreased illumination from the low beams. Fog lights, while useful in specific conditions, do not replace the need for caution when switching from high to low beams.