Why do headlights look brighter at night?

Answer: Dark surroundings increase contrast

Eyes become more sensitive — Wrong. Dark-adapted eyes are more sensitive, but headlights appear brighter primarily because of increased contrast against dark background.

Lights actually get brighter — Wrong. Headlight intensity doesn't change. They appear brighter at night because of contrast—bright light against dark background stands out more.

Dark surroundings increase contrast ✓ — Correct! Perception of brightness is relative. During daytime, sunlight provides high ambient brightness—headlights blend in. At night, low ambient light creates high contrast. Same light intensity appears much brighter against darkness. This is contrast effect—our visual system is more sensitive to relative differences than absolute light levels!