While feeling sad is part of being human, depression is not. For some depressed people, especially teens, their mood may be more irritable than sad.
Clinical depression is a highly treatable disorder which has a variety of causes.
Some research is beginning to establish a possible genetic predisposition for individuals with more serious depressions. This, then causes the brain to function improperly, resulting in depression. However, research also indicates that some depressions, especially mild and moderate cases, do not have any clear genetic components. Thus, there are many ways to bring on clinical depression. Fortunately, counseling, sometimes in combination with medication, is very effective in releasing depressed people from their heavy burdens.