New York (CNN Business) The highly-anticipated dark theme option for Gmail is now rolling out to Android and iOS users.

The new appearance, which flips the default white background in Gmail to black, will begin rolling out immediately, according to a Google blog post. However, it may take 15 days or longer for some users to see the feature, according to the company.

Dark mode is a preferred appearance for some users because it's easier on the eyes. The company says it also prolongs battery life; darker pixels require less power than lighter ones.

The move is part of a larger trend: It's become increasingly popular on several platforms and devices, including Twitter, Samsung Galaxy smartphones, Google's Chrome browser and Apple's iOS and MacOS software. Apple's support page for installing dark mode on Mac claims the setting "makes it easier to stay focused on your work, because your content stands out while darkened controls and windows recede into the background."

Facebook is also testing a dark mode, according to multiple reports

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