Becoming low in mood is a normal emotional reaction that occurs when individuals experience, for example, the loss of someone close, a relationship break-up, or problems at work. ‘Normal’ low mood, however, remains reactive even in adversity with the ability to experience joy if circumstances change. In depressive disorders, mood is pervasively low; if it lifts, this is usually temporary. Depressive episodes can, for example, be precipitated by changing of the seasons, occur with physical or other psychiatric conditions, without obvious cause according to genetic vulnerability, or due to stressful life events; just because there is a good reason to feel low doesn’t mean one hasn’t developed a disorder. If a depressive illness has become established, low mood is associated with a number of other symptoms including reduced energy and pleasure in previously enjoyable activities; disturbed sleep and appetite; restless agitation or significant slowing of movement and thoughts; loss of confidence; and in severe cases, suicidal thoughts. 

The severity and duration, as well as the nature of past episodes and response to treatments, help determine the best intervention. This can range from watchful waiting to psychological therapy and medication. Depending on the nature and factors involved in your depression, there will be different therapeutic techniques (for example, cognitive behavioural, schema, interpersonal, integrative or psychodynamic) and types of medication that are more likely to be helpful. Once the depressive episode is beyond a certain level of severity, only a limited proportion of patients will improve without medical intervention. Yet, approximately 70% of cases respond well to treatment, re-establishing pre-episode levels of motivation and drive, and functioning with family, friends, work or education.