HERE discussing how social media networks influence on a mass scale the emotions of its users, often in a manipulative and negative manner. On social media and "social engineering," see a very good write-up HERE.
For more balanced perspective, "10 Great Articles About Social Media," repeat of an older link HERE.
If I can find some time I'd like to collect/post my thoughts/posts on social media that I've authored here at After Nature over the years. Maybe soon, but again, just need to find free time.