The symptoms can range from mild to severe and the causes of depression can often be complex.

"Physical and social functioning are impaired by depression to a greater degree than by hypertension, diabetes, angina, arthritis, gastrointestinal diseases, lung problems, or back ailments." -Journal of Clinical Psychiatry Nov 1993

Persistent sad, anxious or "empty" mood

Sleeping too little or sleeping too much

Reduced appetite and weight loss, or increased appetite and weight gain

Excessive alcohol consumption is also sometimes a symptom of depression.

Feelings of guilt, worthlessness and helplessness.

Loss of interest or pleasure in hobbies and activities that were once enjoyed, including sex.

Fatigue or loss of energy.

Thoughts of death or suicide.

Restlessness, irritability.

Persistent physical symptoms that do not respond to treatment, such as headaches, digestive disorders, and chronic pain.