[qubitcoder]

I just upgraded to Android 7.0. Night Mode is still there! You can access it by enabling the system UI tuner.

Just swipe down from the top of the screen to reveal the quick settings, and then press and hold the Settings icon (gear) for a few seconds and release. This will enable the UI tuner.

Swipe down from the top again, then tap "EDIT" in the bottom right corner. There should be a tile for "Night mode", which you can drag and drop into the quick settings panel for easy toggling.

[brianjking]

Did you upgrade from DP5?

[ac29]

I didn't and I can confirm the feature isn't there in a 6->7 update.