To be honest, I don't really care about studies, let alone Facebook's own studies. I've seen enough.
Life immediately became less depressing after leaving social media for good. Because my family, especially my cousins, use Facebook and Instagram for communication I'm still forced to use them to a minimal extent. When I do use them, I don't see a lot of happy people. In fact I see a lot of signs of mental instability in the profiles that these two sites want me to see and friend/follow. Lots of narcissism.