If you spend lots of time in front of your Laptop Screen or Desktop Screen you might have some pain or strain in your eyes. This is mostly due to color temperature of your screen.Blue light is short-wavelength visible light that is associated with more eye strain. Reducing the color temperature of your display lowers the amount of blue light emitted by a color display for better long-term viewing comfort.
f.lux do the same job for you. It changes the color temperature of your screen according to time.
i.e. warm at night and like sunlight during day.
It will ask for your location and based on your time zone it will work.
f.lux also has a great brightness control function which can control the brightness of your screen beyond limit of your default brightness control.
To use this function you need to press these key combinations-
Alt + Page Down - Dim the screen
Alt + Page Up - Brighten the screen
https://justgetflux.com/