Mark Zuckerberg, chief executive officer of Meta Platforms Inc., during a dinner with tech leaders in the State Dining Room of the White House in Washington, DC, US, on Thursday, Sept. 4, 2025. US President Donald Trump said he would be imposing tariffs on semiconductor imports “very shortly” but spare goods from companies like Apple Inc. that have pledged to boost their US investments. Photographer: Will Oliver/EPA/Bloomberg via Getty Images
Will Oliver | Bloomberg | Getty Images
Meta halted internal research that purportedly showed that people who stopped using Facebook became less depressed and anxious, according to a legal filing that was released on Friday.
The social media giant was alleged to have initiated the study, dubbed Project Mercury, in late 2019 as way to help it “explore the impact that our apps have on polarization, news consumption, well-being, and daily social interactions,” according to the complaint, filed in the United States District Court for the Northern District of California.
The complaint contains newly unredacted information pertaining to Meta.
The newly released legal brief is related to high-profile multidistrict litigation from a variety of plaintiffs, such as school districts, parents and state attorneys general against social media companies like Meta, Google’s YouTube, Snap and TikTok.
The plaintiffs claim that these businesses were aware that their respective platforms caused various mental health-related harms to children and young adults, but failed to take action and instead misled educators and authorities, among several allegations.
“We strongly disagree with these allegations, which rely on cherry-picked quotes and misinformed opinions in an attempt to present a deliberately misleading picture,” Meta spokesperson Andy Stone said in a statement. “The full record will show that for over a decade, we have listened to parents, researched issues that matter most, and made real changes to protect teens—like introducing Teen Accounts with built-in protections and providing parents with controls to manage their teens’ experiences.”
Google, Snap and TikTok did not immediately respond to a request for comment.
The 2019 Meta research was based on a random sample of consumers who stopped their Facebook and Instagram usage for a month, the lawsuit said. The lawsuit alleged that Meta was disappointed that the initial tests of the study showed that people who stopped using Facebook “for a week reported lower feelings of depression, anxiety, loneliness, and social comparison.”
Meta allegedly chose not to “sound the alarm,” but instead stopped the research, the lawsuit said.
“The company never publicly disclosed the results of its deactivation study,” according to the suit. “Instead, Meta lied to Congress about what it knew.”
The lawsuit cites an unnamed Meta employee who allegedly said, “If the results are bad and we don’t publish and they leak, is it going to look like tobacco companies doing research and knowing cigs were bad and then keeping that info to themselves?”
Stone, in a series of social media posts, pushed back on the lawsuit’s implication that Meta shuttered the internal research after it allegedly showed a causal relationship between its apps and adverse mental-health effects.
Stone characterized the 2019 study as flawed and said it was the reason that the company expressed disappointment. The study, Stone said, merely found that “people who believed using Facebook was bad for them felt better when they stopped using it.”
“This is a confirmation of other public research (“deactivation studies”) out there that demonstrates the same effect,” Stone said in a separate post. “It makes intuitive sense but it doesn’t show anything about the actual effect of using the platform.”
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