Provide a detailed answer to the following question: "What are the long-term effects of using social media on mental health?" Your response should contain at least 5 sentences. Highlight at least 2 sections in your answer with markdown, i.e., *highlighted section*. In your response, the word "impact" should appear at least 3 times. At the end of your response, please explicitly add a postscript starting with "P.S."
user