The biggest smartphone apps are adopting dark mode

The biggest smartphone apps are all launching "dark modes" for users to be able to use their phones at night without hurting their eyes.

Why it matters: Dark mode reduces glare at night and saves battery life.

Facebook appears to be testing a dark mode after the company promised it in April. In April it launched the feature on its Messenger app.

• Gmail's dark mode began rolling out to users last week after teasing it a few weeks ago.
• Instagram is beta testing a dark mode for Android as of last week.
• Twitter has had a night mode since 2016. It introduced an even darker mode earlier this year.

The big picture: A bunch of apps have rolled out dark modes over the past three years, including Reddit, Slack, weather apps and Waze.

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