While Dark Mode may help reduce battery drain attributed to the display, the exact energy savings are highly dependent on the display content. Additionally, users are also asking for platform support for usability and ergonomic reasons: Dark Mode is easier on the eyes, especially at night! The rationale is that pixels are completely turned off, unlike LCD screens where power is required to display both light and dark shades of a pixel. This confirmed the obvious - Dark Mode can significantly help reduce the battery drain on devices with OLED screens.
At the 2018 Android Dev Summit, Google discussed how the choice of colors in Android applications directly affect battery life.
