Most people have felt sad or depressed at times. Feeling depressed can be a normal reaction to loss, life’s struggles, or an injured self-esteem.

But when feelings of intense sadness — including feeling helpless, hopeless, and worthless — last for days to weeks and keep you from functioning normally, your depression may be something more than sadness. It may very well be clinical depression — a treatable medical condition.

WebMD. (2009, September 12). Retrieved from http://www.webmd.com/depression/guide/what-is-depression