Bipolar depression causes a person to experience periods when they feel up and others when they feel down. Mental health professionals only associate unipolar depression with low feelings.

Unipolar depression is another term for major depressive disorder (MDD). It causes people to experience feelings of prolonged sadness alongside several other symptoms.

According to one estimate, 21 million adults in the United States experienced unipolar depression in 2020.

Bipolar depression causes a person to experience changes in mood and energy.

People with bipolar depression often experience periods where they are abnormally happy or irritable. They then also experience periods where they feel sad and low.

Bipolar depression affects approximately 4.4% of U.S. adults at some point in their lives.

This article discusses the similarities and differences between unipolar and bipolar depression. It also discusses their symptoms, causes, and treatment.

For more research-backed information and resources on mental health and well-being, please visit our dedicated hub.

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Unipolar depression, or MDD, is one of the most common mental health conditions in the United States.

Unipolar depression can cause a person to experience feelings of prolonged sadness. It can also cause a person to lose interest in activities they once enjoyed.

Other common symptoms of unipolar depression include:

  • changes in appetite
  • changes in weight unrelated to dieting
  • changes in sleeping patterns
  • increased fatigue
  • the inability to sit still
  • slowed movements or speech
  • feeling worthless
  • feeling guilty
  • difficulty:
    • thinking
    • concentrating
    • making decisions
  • thoughts about death or suicide

Suicide prevention

If you know someone at immediate risk of self-harm, suicide, or hurting another person:

  • Ask the tough question: “Are you considering suicide?”
  • Listen to the person without judgment.
  • Call 911 or the local emergency number, or text TALK to 741741 to communicate with a trained crisis counselor.
  • Stay with the person until professional help arrives.
  • Try to remove any weapons, medications, or other potentially harmful objects if it’s safe to do so.

If you or someone you know is having thoughts of suicide, a prevention hotline can help. The 988 Suicide and Crisis Lifeline is available 24 hours a day at 988. During a crisis, people who are hard of hearing can use their preferred relay service or dial 711 then 988.

Find more links and local resources.

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This type of depression can cause a person to develop emotional and physical problems that can impact their ability to function at work or home.

Learn more about unipolar and other types of depression.

Bipolar depression causes a person to experience changes in:

  • mood
  • energy levels
  • ability to function

A person with bipolar depression will often experience moods that alternate between extreme highs and extreme lows.

Healthcare professionals refer to periods of high moods as manic episodes and periods of low moods as depressive episodes.

Symptoms of a manic episode

During a manic episode, a person may experience the following symptoms:

  • feeling very high and elated
  • feeling extremely irritable or touchy
  • feeling jumpy and wired
  • feeling more active than usual
  • having a decreased need for sleep
  • talking quickly about many different things
  • racing thoughts
  • the ability to do many things at once without tiring
  • an increased appetite for:
    • food
    • drink
    • sex
    • other pleasurable activities
  • untypical feelings of:
    • importance
    • talent
    • power

Learn more about the symptoms of mania.

Symptoms of a depressive episode

During a depressive episode, a person may experience the following symptoms:

  • feeling very sad or anxious
  • feeling slowed down or restless
  • having problems sleeping
  • talking very slowly
  • being unable to find anything to say
  • having trouble concentrating or making decisions
  • losing interest in almost all activities
  • feeling hopeless or worthless
  • thinking about death or suicide

Learn how to spot some of the hidden signs of depression.

Unipolar and bipolar depression have similarities and differences, including symptoms, causes, and treatment.


The depressive symptoms of bipolar depression are often the same as the depressive symptoms of unipolar depression. Both conditions can cause a person to feel extremely sad and hopeless.

People with unipolar depression do not experience manic episodes. Only bipolar depression causes this.

Before diagnosing a person with unipolar depression, a healthcare professional must rule out a history of manic or hypomanic episodes.

Learn the differences between mania and hypomania.


Medical professionals do not fully understand what causes unipolar and bipolar depression. However, both conditions share similar possible causes.

Genetics may play a role in the development of both types of depression.

Studies show that if a person has a first-degree relative with unipolar depression, they are three times more likely to develop the condition than the general population.

Studies also show that genetics play a role in bipolar depression. Scientists have made an association between at least 30 genes and an increased risk of the condition.

Traumatic life events may play a role in the development of unipolar and bipolar depression. These events include:

Learn about bipolar and race.


The National Institute of Mental Health (NIMH) lists psychotherapy as a possible treatment option for bipolar depression and unipolar depression.

Some healthcare professionals refer to psychotherapy as talk therapy. This is a term for treatment techniques that aim to help people identify and change troubling:

  • emotions
  • thoughts
  • behaviors

People can also treat bipolar and unipolar depression with certain medications. This is where the treatment for the two conditions may differ.

Antidepressant medications are often a common treatment option for people with unipolar depression. These medications change how the brain produces or uses certain chemicals that influence mood or stress.

However, a person with bipolar depression should not take antidepressants by themselves. This is because evidence suggests that antidepressants alone are ineffective in treating bipolar depression and can trigger manic episodes.

If a person with bipolar depression takes antidepressants on their own, they may also increase their risk of:

If a person with bipolar depression does take antidepressant medications, they should take them alongside mood stabilizers to help reduce the risk of these side effects.

People with bipolar depression are more likely to seek medical help during a depressive episode than during a manic episode. It is important for a healthcare or mental health professional to take a careful medical history. This can help them determine the correct diagnosis, as bipolar and unipolar depression have similarities.

Learn more about treatment options for bipolar disorder.

A person cannot have bipolar depression and unipolar depression at the same time.

Both conditions share similar depressive symptoms. However, if a person experiences manic and depressive symptoms, they typically have bipolar depression.

If a person has depressive symptoms but does not have manic symptoms, they generally have unipolar depression.

This means the two conditions cannot occur together.

Learn more about the differences between depression and bipolar disorder.

Bipolar depression occurs when a person experiences both manic and depressive episodes. If a person only experiences depressive episodes, they may have unipolar depression.

The depressive episodes of bipolar and unipolar depression can cause similar symptoms, such as sadness, worthlessness, guilt, and restlessness. They can also cause sleeping difficulties, such as insomnia, concentration, and making decisions.

If a person has bipolar disorder and experiences a manic episode, they can feel high, elated, irritable, jumpy, and be more active than usual. They can also have a decreased need for sleep and experience racing thoughts.

People with either condition can benefit from psychotherapy to help treat their symptoms. People with unipolar depression can also treat their condition with antidepressants.

However, taking antidepressants by themselves is not effective for bipolar depression. This is because this medication can trigger a manic episode. People with bipolar depression should take antidepressants alongside mood stabilizers.

If an individual is experiencing symptoms of depression, they should speak with a healthcare or mental health professional.