What are the symptoms of depression in kids?

Some symptoms of depression in children include constant irritability, anger, continuous feelings of sadness and hopelessness; often crying alot. They will also withdraw socially and changes know appetite will occur. They might lose sleep or sleep excessively. In school, they might have difficulty concentrating and are always tired. Sometimes, they might complain of stomachaches and headaches that don't seem to respond to medical attention :(