Signs of depression

How can you distinguish depression from ordinary sadness? Here are the classic symptoms:

* Diminished interest or pleasure in most activities.

* Significant weight loss or weight gain without effort, or loss of appetite.

* Difficulty sleeping, or sleeping too much.

* Psychomotor agitation or retardation.

* Fatigue.

* Feelings of worthlessness or excessive or inappropriate guilt.

* Diminished ability to think or concentrate, or indecisiveness.

* Recurrent thoughts of death or suicide, or a suicide plan or attempt.