Understanding Mood Disorders: A Guide to 9 Common Types
Everyone experiences shifts in their mood. Feeling happy, sad, or irritable are all normal parts of being human. A mood disorder, however, is different. It’s a mental health condition where your general emotional state is distorted or inconsistent with your circumstances, interfering with your ability to function.
These disorders can range from the persistent low of depression to the intense highs and lows of bipolar disorder. Because the treatments are very different, getting a correct diagnosis is the most important step toward feeling better.
This guide, based on the criteria in the American Psychiatric Association’s Diagnostic and Statistical of Mental Disorders (DSM-5), will define the nine most common mood disorders to provide clarity.
Disclaimer: This article is for informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. If you are struggling with your mental health, please consult a qualified healthcare professional.
This guide, based on the criteria in the American Psychiatric Association’s Diagnostic and Statistical of Mental Disorders (DSM-5), will define the nine most common mood disorders to provide clarity.
Depressive Disorders: The "Lows"
This group of disorders is primarily characterized by a persistent feeling of sadness or a lack of interest in outside stimuli.
What is Depression?
Depression (also known as clinical depression or a depressive disorder) is a common but serious mood disorder that negatively affects how you feel, think, and act. It is more than just a passing case of the “blues” or sadness.
Depression is an umbrella term for several conditions. At its core, it causes persistent feelings of sadness and a loss of interest in activities you once enjoyed. It can lead to a variety of emotional and physical problems and can decrease your ability to function at work and at home. Symptoms must be present for at least two weeks for a diagnosis
What is Major Depressive Disorder (MDD)?
Major Depressive Disorder (MDD) is the classic, episodic form of depression. It is defined by experiencing a “depressive episode”—a period of at least two weeks where a person has a depressed mood and/or a loss of interest or pleasure in nearly all activities.
To be diagnosed with MDD, a person must also experience several other symptoms, such as:
Insomnia (inability to sleep) or hypersomnia (sleeping too much).
What is Persistent Depressive Disorder (Dysthymia)?
A person with PDD experiences a depressed mood for most of the day, for more days than not, for at least two years (one year for children and adolescents). While the symptoms may be less severe than a major depressive episode, they are constant and unrelenting, leading to significant impairment over time. It’s often described as a “low-grade” but constant depression that becomes a person’s “new normal.”
Bipolar and Related Disorders: The "Highs and Lows"
This group of disorders is defined by the presence of “high” moods—mania or hypomania—in addition to depressive episodes.
What is Bipolar I Disorder?
Bipolar I Disorder is defined by the experience of at least one manic episode. This is the key diagnostic criteria. A manic episode is a distinct period of abnormally and persistently elevated, expansive, or irritable mood and increased energy, lasting at least one week.
Symptoms of mania include:
Inflated self-esteem or grandiosity.
A decreased need for sleep (e.g., feeling rested after only 3 hours).
Being more talkative than usual or feeling pressure to keep talking.
High distractibility.
Risky behavior (e.g., spending sprees, sexual indiscretions).
What is Bipolar II Disorder?
A hypomanic episode is a milder, shorter version of mania. It lasts for at least four consecutive days and is noticeable to others, but it is not severe enough to cause major impairment in functioning or require hospitalization. Psychosis is not present in hypomania.
What is Cyclothymic Disorder (Cyclothymia)?
However, these symptoms do not meet the full criteria for a hypomanic episode or a major depressive episode. The “highs” aren’t high enough for hypomania, and the “lows” aren’t severe or long-lasting enough for MDD. It’s a chronic, fluctuating mood disturbance.
Other Specific Mood Disorders
These disorders have unique specifiers related to timing or age.
What is Seasonal Affective Disorder (SAD)?
It is a form of depression that is directly related to the change in seasons. Most commonly, it begins in the fall and continues into the winter months, when there is less sunlight, and resolves in the spring or summer. A less common form causes depression in the spring or summer. Symptoms are the same as MDD but occur in a predictable, seasonal pattern.
What is Premenstrual Dysphoric Disorder (PMDD)?
PMDD is defined by a pattern of severe mood symptoms (like extreme mood swings, irritability, anger, depression, or anxiety) that begin in the final week before the onset of menstruation. These symptoms start to improve within a few days after menstruation begins and are minimal or absent in the week post-menstruation. The cyclical, hormone-linked timing is the key to its diagnosis.
What is Disruptive Mood Dysregulation Disorder?
DMDD was added to the DSM-5 to more accurately diagnose children who were often being misdiagnosed with pediatric bipolar disorder. The key feature of DMDD is the child’s mood between the outbursts—they remain chronically irritable or angry most of the day, nearly every day. This is different from the episodic nature of bipolar disorder.
Why These Definitions Matter: Getting the Right Help
Understanding the specific type of mood disorder is essential because the treatment for one can be very different from another. For example, giving an antidepressant (used for MDD) to someone with Bipolar Disorder can sometimes trigger a manic episode.
If you recognize these symptoms in yourself or a loved one, and they are interfering with work, relationships, or your quality of life, it is a sign to seek help. These conditions are not a sign of weakness, and they are highly treatable.