Update: f.lux is now available in the Play Store.
There are many apps that change the color temperature of a screen throughout the day. Many of these apps claim to help users sleep by limiting exposure to blue light at night that can distort the natural circadian rhythm. One of the first and most well-known entrants to this market is f.lux. They have finally released a beta for Android and it is available for testing.
Surprisingly, f.lux arrived to jailbroken iOS devices long before coming to Android. To get access to the beta, users have to make an account on the f.lux forums and request an invitation to the testing group. Afterwards, this page with a link to download the APK and other instructions will be accessible.
The app has been in testing for months and is currently on version 19. It requires a rooted device running Android 4.4 to 6.1, with some Samsung devices not working properly. F.lux intends to host a public beta on Google Play at a later time to make the signup process easier.
The Android N Developer Preview introduced a similar screen dimming feature to f.lux, as well as a system-level dark mode. Presumably, the feature will launch with the next version of Android and will likely be the best solution for users. In the mean time, users can download Twilight or CF.lumen from the Play Store. Both apps do not require root and offers a range of customization options.