Some 15 million Americans struggle with depression—an illness that comes in many forms—from major depression and seasonal affective disorder, to dysthymia and bipolar disorder. Depressive disorder is an illness that involves the body, mood, and thoughts. It interferes with daily life, normal functioning, and causes pain for both the person with the disorder and those who care about him or her.

Treatment may consist of medication, psychotherapy or a combination of both. Research has shown that cognitive behavioral therapy is particularly effective in dealing with depression.

Common misconception: You can pull yourself out of this state if you try harder.