Last week, Google pointed out to developers at the Android Dev Summit that if they build a Dark Theme into their apps, consumers will be able to save some battery life if they enable the setting on their AMOLED-screened phone. Google, as we pointed out in the same article, has been adding a Dark Theme option for many of its own apps as a way to counteract the blinding white backgrounds used on the company's Material Design.
With Dark Theme enabled, the black text on white background turns into white text on a black background. During the night, or in low-lit rooms, this helps to protect your eyes and the eyes of other people in a darkened room.
9to5 Google stated yesterday that the update to version 3.2 of the app might have to be followed with a force stop in order for the Dark Theme option to kick in. Our Pixel 2 XL, powered by Android 9 Pie, has not yet been updated. You'll know that the update hit your phone when you see "Turn dark theme on" just above Settings.
While we haven't received the update yet, others have and at least one of them posted a review in the Play Store, giving the Dark Theme 5 stars.