Depression is more than just sadness. While it is normal to feel sad or “blue” sometimes, when feelings of sadness last for two weeks or longer and they interfere with daily life activities, it suggests something more serious, such as clinical depression. Symptoms of depression may include low mood, a lack of interest and pleasure in daily activities, reduced ability to concentrate, feelings of worthlessness or excessive guilt, a tendency to think very negative thoughts, reduced energy and/or motivation, significantly increased or decreased sleep, significant weight loss or gain, and recurrent thoughts of death or suicide. Depression is the most common mental health disorder and occurs in about 20% of the population.
Depression is not caused by one thing, but by the interaction of biological and psychological factors. Biological factors can include genetics (family history), hormones, and brain chemistry, as well as medical illness, injury and pain, while psychological factors can include stressful life events, response to loss or transition, and unhelpful/ negative thinking styles.