Depression is more than just the occasional bad mood.
Depression can be difficult to diagnose or to recognize in oneself.
The symptoms of depression easily hide behind the ordinary experience of life. A glimpse at the National Institutes of Health's symptoms of depression checklist reveals that depression overlaps normal, healthy living at many points, because of this a professional is needed to make definitive diagnosis. We must look first at intensity. If any one symptom significantly interferes with friends, family, or work, it can indicate depression. We must also look at duration.