What is night mode and how do I use it?

One of the features listed is “night mode” which turns off the display screen.

The night mode function allows you to automatically schedule the clock display to go dark during a preset time interval. You can turn on night mode and set the time interval by following the steps below:

1) Make sure the clock is already set up and connected to your home Wi-Fi network. 
2) Go to the Reason Home app on your smartphone.
3) Tap the clock's icon on the "Home" screen.
4) Tap the Settings (a gear icon) at the top right.
5) Under "Settings," find "Night Mode." Then swipe the toggle switch to the right to turn on and set the start and end times of the desired time interval.

Note: Currently, the start and end times are limited to specifying hours in 24hr time, so you cannot set the night mode from 9:15-6:30, but you can set it from 21:00 to 6:00.