Mood disorders, also known as "mood (affective) disorders," are those conditions that affect your emotional state. For example, depression and bipolar are mood disorders.
The mental health profession’s Diagnostic and Statistical Manual of Mental Disorders V (also known as the DSM5) also includes under mood disorders those brought on by substances such as alcohol and benzodiazepines (for example, Valium), those due to a medical condition, and mood disorders “not otherwise specified.”
A mood disorder such as clinical depression is different than the blues you may feel after an upsetting life event, work disappointment, or relationship break-up. These feelings of sadness or unhappiness are triggered by a specific event, from which you’ll likely recover and move on. A mood disorder, on the other hand, is a serious and long-term condition that will need professional treatment and therapy.
Not sure whether you’re having a rough patch in your life that’s depressing you or you’ve got a mood disorder? You may want to check out the article Is It Another Bad Day – or Depression? to get a better sense of where you are.