Dark mode on iOS 13 not only takes care of your eyes when interacting with the phone in the dark, but
Dark Mode: Benefits
Phonebuff conducted an experiment and shared itresults with other users on YouTube. Both iPhones were fully charged, the new iOS 13 operating system was installed on them. Dark mode was activated on one of them, and Light mode on the other. The experiment went on until the iPhone "died." By the way, the test results were more than convincing. See for yourself ...
The test showed that the iPhone XS Max using"Dark mode", consumes significantly less battery power than the iPhone XS Max, which uses light mode. When the iPhone XS Max with the light mode turned on died, another iPhone with the active Dark Mode had up to 30 percent of the battery life.
PhoneBuff notes one important testa variable that influenced the results: both iPhones had brightness settings of 200 nits. With 100 nits, two hours on Twitter saved 5 percent more battery power in dark mode. The 300 nit test, which is closer to using the smartphone outdoors, showed that dark mode saves 12 percent of the battery.
In any case, the test shows that the dark modeis a significant battery saver for OLED iPhones, including the iPhone X, iPhone XS and iPhone 11 Pro, but this is not about the iPhone XR or iPhone 11.