Introduction
Depression is one of the most common mental health problems globally, and is characterised by the inability to enjoy life and experience pleasure (American Psychiatric Association, 2013; Ministry of Health, 2013).
It can lead to emotional and physical problems, and causes distress for the person with depression and friends and family who care for them. From this perspective it is reasonable to distinguish depression from occasional low mood because it is a constant feeling of sadness, worthlessness and a lack of aspiration to engage in formerly pleasurable behaviour.