Step 1: Download and install Night Mode Enabler from Google Play Store.
Step 2: Pull down on your notification bar twice to open the Quick Settings
Step 3: Press and hold the little gear icon for about 10 seconds.
Now open Night Mode Enable app and tap Enable night mode button. This will bring you to the System UI Tuner entry for Night Mode, which is hidden by default. Here you have to click On to enable Night mode. Once you’ve done this, Night Mode option should be included in your Quick Settings title along with Bluetooth, Airplane mode and few others.