Chances are, you're simply experiencing a case of the blues. Sometimes it's easy to trace sadness back to a specific event—a fight with a friend, a harsh word from your boss, the death of a loved one, or even a streak of sunless days. Other times, you might feel as though you're down in the dumps for no reason in particular. What makes sadness different from clinical depression is the length of time it stays with you, and your ability to deal with it. If you're feeling sad now and then, but your bummed-out mood isn't interfering with your ability to function and you’re still enjoying activities you've always enjoyed, then you're probably just temporarily down. 

Recognize that these feelings of sadness are normal—in fact, a little sadness can even be healthy—and that they will go away. In the meantime, find ways to spend time with friends and loved ones. "Being with others is therapeutic and healing in almost all situations," says Carol Landau, PhD, a clinical professor of psychiatry and medicine at Alpert Medical School at Brown University.