Depression comes in many shapes and sizes. It can last for brief periods of time or linger for years.
Depression ranges in severity from being relatively mild to incapcitating.
Sadness, however, may not always be the dominant feeling of a depressed person. Depression can also be experienced as a numb or empty feeling, or perhaps no awareness of feeling at all. A depressed person may experience a noticeable loss in their ability to feel pleasure about anything. Any of these symptoms can last for brief periods of time or linger for years. Being clinically depressed is very different from the down type of feeling all people experience from time to time.