system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Is it better for your eyes if a screen is too bright or too dim, and why?
gpt
It's best if the screen matches the surroundings.

A bright screen in bright light means it's easier to see, and less work for your eyes.

A dim screen in low light prevents too much light harming your eyes from a directed source.