Night Screen9

Night screen main goal is to reduce the brightness of your screen lower than you can achieve with the default settings. This application applies an overlay filter that acts as a dimmer to darken the screen. It helps to avoid headache and eye pain in a dark environment or at night.
Features:
easy to use;
can automatically set default brightness settings in Android to the minimum;
restore default brightness settings after stop the app;
keep the screen on while the app is running (optional);
amazing blue light filter to help you have a better sleep (optional)
supports dimming the transparent navigation bar in Android 4.4 and higher;
extra-content: auto-enable - disable feature and one-click widget
How to make it work on Xiaomi phones: go to Settings Apps this app allow popup