Often people who are depressed show little emotional expression. Other times, they show too much. They can be suddenly irritable or explosive. They may express exaggerated feelings of sadness, hopelessness, worry, or fear. Some are caught up in a sense of worthlessness or a feeling of excessive or inappropriate guilt. The key is a sudden change in behavior. If a person who is usually flat with their feelings becomes hyperemotional, depression may be the cause.