Depression is a mood disorder wherein the patient exhibits persistent sadness, irritability and sleeping problems. To be diagnosed with one of the major classes of depression, the symptoms must interfere in the patient's life. Each of the major classes of depression---major depression, minor depression, dysthymia, seasonal affective disorder and postpartum depression---have specific causes and symptoms.
Major Depression
The National Institutes of Health (NIH) defines major depression as a form of depression where the patient exhibits five or more symptoms for two or more weeks. Changes in mood include agitation, feeling hopeless, self-hate, and thoughts of death and suicide. Behavioral symptoms of major depression are appetite changes, concentration problems, fatigue, inactivity and sleeping problems.
Minor Depression
The NIH states that minor depression is similar to major depression. Patients with minor depression, however, have only two to four symptoms, which last two or more weeks.
Dysthymia
Dysthymia is a chronic form of depression, but has less severe symptoms when compared to major depression, according to the NIH. Symptoms include concentration problems, feeling hopeless, fatigue, low self-esteem, appetite changes and insomnia or hypersomnia; these symptoms occur daily for at least two years. The NIH states that patients can have dysthymia alone or with another psychological disorder.
Seasonal Affective Disorder
Seasonal affective disorder, or SAD, is a form of depression that occurs during the winter months. The NIH notes that the causes of seasonal affective disorder are not known, but probable causes include changes in ambient light, body temperature and hormone regulation. Symptoms include social withdrawal, afternoon energy slumps, carbohydrate cravings, lack of energy, increase appetite, and increased sleep and daytime sleepiness.
Postpartum Depression
Postpartum depression affects women after they give birth and ranges from moderate to severe depression. The NIH states that symptoms begin within four weeks after delivery and are similar to the symptoms of major depression.
