Spotlight: Red Moon for Android is a great blue-light filtering app, alternative to f.lux and Twilight

Blue-light screen filters are totally not newcomers to the world of mobile devices - these have been around for a long time, sparing us from the undesired side effects of blue light late in the evening. Long story short, turns out that the blue light our phone's display emit mess up with our Circadian rhythms and as a result, we are unable to fall asleep easy. This is where such filters come into play - they filter our the blues and make your display predominantly reddish.

Apps like f.lux and Twilight for Android are rather popular, but if neither of these floats your boat due to one reason or another, then you might want to check Red Moon. 

It's an open-source blue-light filter that has all the features you might actually want from such an app. It allows you to set the color temperature of the filter, the intensity levels, and dim levels, and finally, supports multiple profiles. 

You can also set Red Moon to automatically lower the brightness when it's running, too. Speaking of automation, you can set Red Moon to automatically enable itself at a preset time. What else might you possibly want?

While the app is priced at $1.99 on Android, but the developer was good enough to provide it as a free APK download on F-Droid.