Understanding Depression, Are There Different Kinds of Depression? Because the term "depression" has taken on such broad meaning in the general public, it's difficult to really describe a range of different emotional and psychological phenomena because they all involve some aspects of this thing called "depression".  In terms of the formal diagnoses that are made by mental health professionals, there are different conditions which involve depressed mood which have been identified.  It might be helpful to know some of these to more easily describe the various forms that depression can take. While some may seem, by their description, to be less serious than others, all have the capacity to diminish life experiences.  Thus, this page is intended to help you describe your experience with depression (or that of a person you care about) as you seek the help and support you may need.  
A Major Depressive Episode
A Major Depressive Episode is described as a period of at least 2 weeks of depressed mood or a loss of pleasure or interest in the activities of life.  In order to formally diagnose a Major Depressive Episode, at least four of the symptoms associated with depression must also be present.  Several of these characteristics are described in the main Depression Page. Sometimes, however, experiencing the full range of symptoms for depression is perfectly normal.  For example, the loss of a loved one would naturally result in a person feeling so pushed down by the weight of the difficult loss that they lack interest in their normal life activities and feel overwhelming sadness.  In such a case, the experience is regarded as Bereavement and not Depression, although they may look and feel the same.  Similarly, there are times that a person experiences some of the indicators of depression in reaction to some event or situation (such as moving, a romantic break-up, surviving a traumatic accident, etc) but not enough to warrant the diagnosis of a Major Depression.  These are regarded as problems in adjustment and, while they are not the equivalent of a major depression, they can evolve into one if the person is unable to recover from the difficult adjustment period. If a person has been feeling the depressed mood or suffering a loss of interest and motivation in a way that is clearly different than they typically are and 4 or more of the other indicators of a major depressive episode are present, then mental health professionals regard that person as struggling with Major Depression (or a Major Depressive Episode). 
Dysthymia
Sometimes, an individual seems to have been depressed so long it almost seems normal.  The depressed mood is not accompanied by enough of the depression symptoms to meet the criteria for a Major Depression, perhaps because the depressed mood has been present for so long, the individual has learned to function enough that other symptoms do not take root.  This condition, formally defined by a depressed mood for 2 or more years of feeling down and unmotivated more days than not, is regarded as Dysthymia by mental health professionals.  In addition to the "feeling down", disrupted sleep and appetite, poor concentration, low energy or fatigue, lack of confidence or low self esteem, and feelings of hopelessness are all associated with Dysthymia.  While not all are present, if two or more of these states (in addition to the sad or down mood) are ongoing, professional intervention may be needed to help overcome the difficulty. 
Other Depressive Disorders
In order for mental health professionals to communicate with each other in order to understand and study the different challenges they witness in people seeking help, it is necessary to classify the difficulties into diagnostic criteria (such as Major Depression, Dsythymia, etc).  However, there are times that difficulties are presented that do not completely fit the identified diagnoses.  This does not mean that the distress being experienced by people is not significant.  Therefore, if some of the descriptions of Major Depression do not seem to fit, yet the feeling is one of "being depressed" in the general public's understanding of "feeling down and out" should still be acknowledged and attended to.  Mental health professionals do not need a formal diagnostic criteria to recognize that someone is struggling.  Whether you or someone you care about is feeling down because of something identifiable (like a romantic break-up, failing an important class, or enduring a family crisis) or whether the depressed feeling seems to have no origin, talking to someone with expertise in the various types of depression may be helpful.  
Other Mood Difficulties Involving Depression : Mental health experts have identified other psychological difficulties involving depression. Among the more talked about is Bipolar Disorder.  Although Bipolar Disorder falls under the more broad classification of Mood Disorder (rather than being regarded as a type of depression), depression is one component of this problem. This has been called "Manic Depression" in the public eye, but that term did not sufficiently describe the complete psychological picture.   The term "bipolar disorder" defines the essential nature of the problem in that there are two "poles" of emotional/psychological functioning involved.  Whereas depression is characterized by the one psychological state of being stuck toward the extreme of feeling down and unmotivated, bipolar disorders involve these depressive episodes and also shifts to the other extreme: elevated mood and increase energy and activity, often with significant decreases in the need for sleep.  This elevated state is termed a "manic episode" (hence the previous name, "manic depression").  Although this episode may feel positive and can involve a lot of positive productivity, these elevated moods can be quite problematic as they often involve irresponsible or risky behaviors, usually in very impulsive fashion with little judgment regarding consequences.  Examples of these behaviors would be spending beyond one's limits or unsafe sexual activity, often on a careless whim or impulse.  Describing the specifics of different kinds of Bipolar disorders is beyond the scope of this page; however, this section is included here because some individuals who report problems with depressed mood may not realize that they are only presenting one dimension of their overall psychological problem (because often the elevated mood is not experienced as a problem!).  Another problem, Cyclothymia, is similar to bipolar disorders except the severity of each extreme (in the depressed episode and in the manic episode) is not sufficient to meet a diagnosis of Bipolar disorder.  Nevertheless, all of the conditions which mental health professionals regard as Mood Disorders, have some component to them that involves some aspects of depression and can be very disruptive to an individuals daily living.