Depression is a neurological disorder. When a person is too overcome with negative emotions, it becomes difficult to focus on any other issue. The person may become lethargic and lose interest in what is going on around them. Such a state may occur when a person fails in an examination, loses a job, gets jilted by a lover, gets divorced, loses some dear one, etc. Some people are able to get over their emotions quickly. But in some others, depressions may last for several days, weeks or even months.