system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it that when we sit in the sun with our eyes closed for a while, when we open them again colours look so much more vibrant?
gpt
The skin of your eyelids lets light shine through. But there's blood inside that skin. So you see a red/orange color. After you've stared at red/orange for a while the color cones in your eyes get "tired". When you open your eyes, the opposite colors - green/blue -  will look way bright because those cones are fresh.