Sometimes we compare our lives with others around us to gauge how we're doing. This is no big deal, but when you combine this with a lot of time on Facebook, you may feel depressed. That's what researchers at the University of Houston discovered. After using Facebook, those users who spent more time online felt more symptoms of depression. Facebook doesn't cause depression, but comparison behavior can leave you feeling in the dumps. One survey found that nearly 70 percent of Facebook users felt somewhat depressed or depressed all the time after spending time online. Limit your exposure to all the excitement, vacationing, parties, and endless fun photos. Fill that time with more things you want to do, and recognize that online you're seeing only one side of people's lives.