system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is blue light from screens harmful and strenuous on our eyes, while blue objects in the environment, are not?
gpt
The issue is that screens shine blue-rich light straight into our eyes, When we are outside, the light is mainly sunshine, which is green-rich.

The other problem is this blue light acts like sunshine to our brains, telling them that it is still daytime, and that we should remain alert and awake. If you are using your device late at night, this is going to mess up your sleep. Blue light in the daytime is fine, because it's good to be awake in the daytime. And blue items in your room are only lit by what lights you have - generally more yellow-rich warm white lighting fixtures - and are a whole lot dimmer.