Introduction

The term "depression" covers a wide range of thoughts, behaviors, and feelings. It is also one of the most commonly used terms to describe a wide range of negative moods. In fact there are many types of depression, each of which vary in the number of symptoms, their severity, and persistence. The prevalence of depression is surprisingly high. Between 5 and 12 percent of men and 10 to 20 percent of women in the United States will suffer from a major depressive episode at some time in their lives. Approximately half of these individuals will become depressed more than once, and up to 10 percent will experience manic phases where they are elated and excited, in addition to depressive ones; an illness known as "manic-depressive" or bipolar disorder. Depression can involve the body, mood, thoughts, and many aspects of life. It affects the way people eat and sleep, the way they feel...