Everyone experiences grief and sadness times, just as we experience happiness and joy. Moods come and go, and cycles of emotional and downs are a normal part of life. However, ongoing feelings of profound sadness that are accompanied by feelings of hopelessness, fatigue, difficulty in concentrating, disturbed sleep and eating habits, and a loss of pleasure in activities that you would normally find pleasurable are an indication of depression. The spectrum of depression ranges widely, from feeling low to serious contemplation of suicide. Depression can be caused by a number of factors, but it is usually the result of either a traumatic life event or an imbalance in brain chemistry.