I've definitely noticed this myself. Friends that I've known to be depressed almost always posted very frequently on Facebook and those that had some negative

I've definitely noticed this myself. Friends that I've known to be depressed almost always posted very frequently on Facebook and those that had some negative life event occur almost always seemed to post way more than usual in the following months. It got to the point that back when I used FB, I would make a point of asking old friends how they were doing when I noticed an uptick in their posting habits.