Bipolar Disorder

It is a medical condition, not a personality quirk: mood and energy shift far beyond the ordinary ups and downs.

By Greg Goodwin · Published October 17, 2026 · Updated October 24, 2026

Cheat Sheet

Prevalence: an estimated 2.8% of US adults had it in the past year and 4.4% experience it at some point in life (NIMH, from 2001-2003 survey data).
Bipolar I: manic episodes lasting at least 7 days, or severe enough to need hospital care; depressive episodes, typically at least 2 weeks, usually occur too.
Bipolar II: a pattern of depressive and hypomanic episodes, with hypomania less severe than the mania of bipolar I.
Cyclothymic disorder: recurrent hypomanic and depressive symptoms that fall short of full episodes.
Rapid cycling: four or more episodes of mania or depression within a year.
Antidepressant caution: antidepressants are not used alone in bipolar disorder because they can trigger mania or rapid cycling.

The 60-Second Version

Bipolar disorder is a mental illness that causes clear shifts in a person's mood, energy, activity levels, and concentration. During manic episodes, a person may feel extremely "up," elated, or irritable and be far more active than usual. During depressive episodes, they may feel sad, indifferent, or hopeless, with very little energy. Some people have hypomanic episodes, a milder version of mania. The condition was formerly called manic-depressive illness. Symptoms usually begin in late adolescence or early adulthood, and between episodes mood often returns to a healthy baseline. Its exact cause is unknown, but genes, brain structure and function, and stressful life events all seem to play a part. Bipolar disorder usually requires lifelong treatment, typically medication, psychotherapy, or both, and good care can meaningfully improve functioning and quality of life. This is general information, not medical advice, so anyone worried about their own mood should talk with a health care provider.

The Long Version

Two Poles, Many Shades

Bipolar disorder is built around mood episodes that last a week or two, sometimes longer, with symptoms present most of the day, every day. A manic episode can bring racing thoughts, a decreased need for sleep, fast talk that jumps between topics, and feelings of being unusually important, talented, or powerful. A major depressive episode can bring a lack of interest in almost all activities, trouble concentrating, changes in sleep, and feelings of worthlessness or hopelessness. Some episodes are "mixed," with both kinds of symptoms at once. The changes are noticeable to others and more extreme than the ordinary ups and downs everyone experiences.

A Spectrum of Types

Clinicians describe three basic types. Bipolar I is defined by manic episodes lasting at least a week, or severe enough to need hospital care, and usually includes separate depressive episodes. Bipolar II involves depressive and hypomanic episodes, and many people with it spend long stretches in a low-grade depressive state. Cyclothymic disorder involves recurring hypomanic and depressive symptoms that are not intense or long enough to count as full episodes. A fourth category covers symptoms that do not match any of the three. In the United States, NIMH estimates that about 2.8 percent of adults had bipolar disorder in the past year.

Causes: Genes, Brain, and Stress

The exact cause is unknown. Bipolar disorder runs in families, and research suggests this is largely due to heredity, but many genes are involved and no single gene causes it. Studies of identical twins show one twin can develop the condition while the other does not, so genes are not destiny. Brain structure and function may also differ in people with bipolar disorder, and people with genetic risk may be more likely to develop it after trauma or other stressful events.

Getting the Diagnosis Right

Diagnosis rests on the severity, length, and frequency of symptoms over a person's lifetime, plus family history. Some people live with the condition for years before it is recognized. People with bipolar II may seek help only for depression, and mild hypomania can go unnoticed. Symptoms can resemble other illnesses, and thyroid disease or certain substances can mimic mood symptoms, so clinicians may order medical tests. Many people also have other conditions, such as anxiety disorders, ADHD, substance misuse, or eating disorders.

Treatment and Living Well

Treatment can help many people, even those with severe forms. Medications such as mood stabilizers and atypical antipsychotics are common, and several kinds of psychotherapy, including family-focused therapy and interpersonal and social rhythm therapy, work well alongside them. For severe cases, brain stimulation such as ECT may be considered. Keeping steady routines for eating, sleeping, and exercise helps, and stopping medication without talking to a provider is discouraged. Stigma can keep people from seeking help, which is part of why accurate information matters. In the US, anyone in crisis can call or text 988.

Why People Care

Millions of people live with bipolar disorder, and many go years without a diagnosis, so recognizing the signs matters for friends and families as well as patients. Understanding it also cuts through stigma and myths, making it easier to support someone and to encourage professional care.

Glossary

Mania: An episode of unusually elevated, energized, or irritable mood with a marked increase in activity.
Hypomania: A milder form of a manic episode that interferes less with daily life.
Mixed episode: An episode that includes both manic and depressive symptoms.
Mood stabilizer: A class of medication used to help prevent mood episodes or reduce their severity.
Psychotherapy: Talk therapy that helps a person identify and change troubling emotions, thoughts, and behaviors.

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