Depression is classified as a mood disorder. It may be described as feelings of sadness, loss, or anger that interfere with a person’s everyday activities. It’s also fairly common. The Centers for Disease Control and Prevention (CDC)Trusted Source estimates that 8.1 percent of American adults ages 20 and over had depression in any given 2-week period from 2013 to 2016.People experience depression in different ways. It may interfere with your daily work, resulting in lost time and lower productivity.