In order to recognize the signs of depression, it is important to understand the parameters of the condition itself. There is a popular misconception that depression is merely the experience of a melancholy "blue" mood, such as that experienced with grief, loss, or other hardships. However, the condition of depression is defined by the presence of "blue" symptoms, but for a prolonged period of time, and unrelated to, or at least disproportionate to any triggering event or situation. Depression also entails experiencing these effects to such a degree that it begins to have an adverse effect on one's daily life, interpersonal relationships, job, or self-perception.

There are many basic signs that may indicate a depressive disorder. All of these signs do not necessarily need to be present, nor is the presence of one sign proof of the disorder. These signs include a loss of interest in previously enjoyed activities, pervasive feelings of worthlessness, prolonged periods of sadness that are not associated with any specific event, the onset of social phobias, fatigue, sexual dysfunction, poor concentration, irritability, sleep disorders, and loss of appetite. Specific types of depressive disorders are indicated by the presence of several of these signs, in conjunction with certain behaviors.

Dysthemic Signs of Depression

Dysthemia is a common form of depression, characterized by a prolonged depressed mood. While not as debilitating as clinical depression, dysthemia still poses a significant threat. Its causes are largely unknown, however, a number of outward signs usually confirm the presence of the disorder. People with Dysthemia experience a depressed mood for the majority of nearly each day, and the feeling exist continuously for at least two years. Eating disorders at both extremes (poor appetite or overeating) are also a sign of this disorder. Other signs include continual difficulties with concentration, sleeplessness, constant low self-esteem, and episodes of low energy and fatigue that are not due to any physical factors.

Signs of cyclothymia, another depression disorder, are often similar to those of bipolar disorder. Like bipolar disorder, this condition includes mood swings from periods of mania to periods of depression. However, in cyclothymic depression, the intensity of the swings is less severe, yet the tend to occur more often and abruptly. Signs of this disorder include the experience of alternating periods of hypermania with periods of depression, independent of any reasonable catalyst, for a span of at least two years. In addition, individuals must not have gone more than two months during that span without experiencing any symptoms.