Darker colours tend to draw the least amount of power on most smartphones with OLED panels.
What's interesting is the comparison between the original Pixel, which uses an OLED screen, and the LCD-sporting iPhone 7. On Google Maps, even at full brightness, using night mode can save about 30 percent of the battery. In the Dark Mode, the battery consumption was reduced to 63 percent on the Pixel to 92mA.
With OLEDs, pixels are essentially turned off when displaying the color black, whereas LCDs keep their pixels lit up no matter what is being shown on the screen. In simple word this well-known feature, of course, the Dark Mode will simply increase the autonomy of the device, hence, as a result, users will get more use time. But black has hardly any power draw - maximum brightness black uses about a third of the power consumed by maximum brightness white.
The company studied energy consumptions on phones with white and dark themes and concluded that at max brightness, the dark mode on OLED always wins. The company plans to introduce the dark mode to its Phone app after getting it to YouTube and Android Messages.
Google has finally confirmed that dark mode on Android phones uses less power and saves battery life.
I encourage you to switch to night mode (where available) not just because your phone will last longer, but because it's easier on the eyes. The latest example that can be cited here is the YouTube dark theme. But battery life is never enough, especially as the battery degrades over time. One of their solutions was to implement a dark UI.
Google are rolling out a new In-App Updates API that will let apps updated while still running.
There aren't many popular third-party apps that support dark theme (are you listening Facebook?), but Twitter isn't one of them. One hopes that the transparency of its reporting will extend more fulsomely to China in the future, since almost 1 in 5 people on Earth call it home.