[Meta Sued for Concealing 'Causal' Evidence of Social Media's Harm to Mental Health] According to reports from Zhitong Finance, in a class-action lawsuit filed by multiple U.S. school districts against Meta and other social media platforms, the full lawsuit documents revealed that the company halted internal research after discovering causal evidence that its products, Facebook and Instagram, negatively impact users' mental health. Meta's internal documents obtained through investigation show that in a 2020 research project codenamed 'Project Mercury,' Meta's researchers collaborated with Nielsen to evaluate the effects of discontinuing the use of Facebook and Instagram. The internal documents noted that the results were quite unsatisfactory for the company: 'Users who stopped using Facebook for one week reported reduced feelings of depression, anxiety, loneliness, and social comparison.' The lawsuit documents state that despite Meta's own research confirming a causal link between its products and harm to users' mental health, the company told the U.S. Congress that it could not quantify whether its products harm teenage girls.