These days many of the users spend most of their time on PC only for using the web browsers. When you are using so much time staring at websites, you should ensure that those sites are not affecting your eyesight negatively. For protecting your eyes you can either use a software like f.lux which changes the color of your screen and lowers the blue light coming from the screen, or you can use a web browser extension like Night Shift mode.
The Night Shift mode extension for Firefox browser can change the color of webpages and make them look dimmer so that the webpages are easier to view at the night time (hence the name Night Shift mode). As soon as you install this extension, it switches the webpages to warmer color.
By default, it changes the color at any time of the day. But you can change the schedule of Night Shift mode and make it change color only at night time (6 PM to 6 AM), change the schedule to sunset to sunrise or you can also set a custom schedule for the extension that is convenient for you. You can also set the colors that are to be used for setting the warmer colors for your screen. Along with the different colors you can also set the color temperature from less warm, warm and more warm by using a slider control.
Conclusion: Night Shift mode extension does the same to your Firefox web browser as the f.lux program does in Windows and macOS. It changes the webpages to have warmer colors so that your eyes stay safer and healthier. It comes with an automatic scheduler using which you can make it automatically use warmer colors for webpages at night time.
You can get Night Shift Mode extension for Firefox from https://addons.mozilla.org/en-US/firefox/addon/night-shift-mode/.