This app helps to activate the Android night mode on devices that do not provide this option in the system settings.
This app will not work on all devices since some smartphone manufacturers disabled or blocked this option for their devices!
This FAQ answers the most commonly asked questions:
Since Nov. 21, 2019 some Samsung Galaxy devices repeatedly switch back to day mode. This is not an issue with the Dark Mode app but with the Email app by Samsung.
Check out the FAQ for more information on how to fix this issue: