Millions of Americans experience some sort of sadness or depression during their lifetime. In fact, the Anxiety & Depression Association of America (ADAA) cites that depression is one of the most common mental illnesses in the United States. While sadness is often a symptom of depression, behavioral health professionals note that there is a distinction between the two feelings. Knowing if you are depressed or just sad and when to get professional help is key to maintaining your optimal mental health. Read more.