The moods of people are highly dependent on the characteristics and surroundings around them. People might think of sadness, feeling low and loss of interest as just a mood swing. But many times this loss of interest in work can also be depression. The prime symptom of depression is the continuity of this behavior. Depression is a disorder where people have the feeling of being sad and lonely all the time. The change can be easily witnessed in the day to day change of mood with the person.