Clinical depression is a serious and common disorder of mood that is pervasive, intense and attacks the mind and body at the same time. Current theories indicate that clinical depression may be associated with an imbalance of chemicals in the brain that carry communications between nerve cells that control mood and other bodily systems. Other factors may also come into play, such as negative life experiences such as stress or loss, medication, other medical illnesses, and certain personality traits and genetic factors. The symptoms of depression include feeling sad and blue, not enjoying activities once found pleasurable, having difficulty doing things that used to be easy to do, restlessness, fatigue, changes in sleep, appetite or weight, inability to make decisions, feelings of worthlessness, and thoughts of death or suicide. Major depression is the most common type of depression and is characterized by at least five of the major symptoms of depression.
Dysthymia is a milder form of depression that lasts two years or more.
It is the second most common type of depression but because people with dysthymia may only have two or three symptoms, may be overlooked and go undiagnosed and untreated. Bipolar depression is the depressive phase of manic-depressive illness, in which there are both extreme highs and extreme lows. Bipolar depression symptoms are similar to those of major depression, with certain variations such as excessive sleep and increase in appetite. Seasonal Affective Disorder is a type of depression that follows seasonal rhythms, with symptoms occurring in the winter months and diminishing in spring and summer. Current research indicates that the absence of sunlight triggers a biochemical reaction that may cause symptoms such as loss of energy, decreased activity, sadness, excessive eating and sleeping.