SC-Filter

Tap the button to darken the screen.
Stop with the notification bar and tap button.
You may reduce the glare on the screen at night.

In addition as tool, you can display your notes and time on the screen.
This is useful when you want to measure the time while using other apps, or have notes that you want to remember for study or daily life.
You can also adjust the filter color, transparency, and cancel time setting. You can set the screen gradually darkened at night and stop in the morning.

And others, You can play with various effects on your screen.

About permissions:
This app require "display over other apps" permission. If this app cannot launch or the filter is not applied, check if the permission is valid.
Continue screen filtering with "foreground permission". The notification bar is displayed during filtering.
"prevent from sleeping" is used to avoid the screen filter shutdown. You can adjust this duration at the setting screen (default 6 hours).
After purchase, the daily filter is unlocked and you can keep three settings to save and switch filters.

All you need to start and end is a tap.
Various customization is also possible. It's all yours.
I wish this app make you comfort or fun.