Bipolar disorder is a mental health condition that causes unusual shifts in mood, energy, and activity levels, cycling between emotional highs (mania or hypomania) and lows (depression). About 37 million people worldwide live with it, roughly 1 in 200 people. It primarily appears during working age, though it can also develop in adolescence.
Unlike ordinary mood swings, bipolar episodes can last days, weeks, or even months and are intense enough to disrupt sleep, judgment, relationships, and the ability to function at work or school.
Types of Bipolar Disorder
There are several forms of bipolar disorder, and the differences come down to how severe the highs get and how long the cycles last.
Bipolar I involves full manic episodes that last at least seven days (or are severe enough to require hospital care). These manic episodes are often followed by depressive episodes lasting two weeks or more. Some people with bipolar I experience psychosis during mania, meaning they lose touch with reality through delusions or hallucinations.
Bipolar II involves hypomanic episodes, which are a less intense form of mania, paired with longer and often more debilitating depressive episodes. Hypomania may actually feel productive or pleasant, which is one reason bipolar II frequently goes undiagnosed. People with bipolar II never reach full mania, but the depressive episodes tend to dominate their experience of the illness.
Cyclothymic disorder is a milder but chronic form, involving ongoing fluctuations between low-level depressive and hypomanic symptoms that never quite meet the full criteria for a major episode. Current diagnostic guidelines focus on these episodic mood symptoms, though some researchers argue the condition is better understood as a temperament pattern rather than a series of discrete episodes.
What Mania and Depression Feel Like
During a manic episode, you might feel euphoric, wired, or unstoppable. Sleep feels unnecessary: you might go days sleeping only two or three hours and feel completely rested. Thoughts race, speech speeds up, and ideas flow so fast they’re hard to track. Confidence surges, sometimes to the point of grandiosity, where you believe you have special abilities or importance. The danger is in the decisions: spending sprees, risky sexual behavior, impulsive business ventures, or quitting a job on a whim.
Depressive episodes look more like what most people picture when they think of depression. Energy drains away. Activities that once brought pleasure feel meaningless. Concentration falters, sleep either increases dramatically or becomes difficult, and feelings of worthlessness or guilt can become overwhelming. For many people with bipolar disorder, these depressive phases are actually the most disabling part of the illness, lasting longer and occurring more frequently than manic episodes.
Mixed Features
Sometimes mania and depression don’t take turns. In episodes with “mixed features,” symptoms of both states overlap. You might feel the restless energy of mania while simultaneously experiencing deep sadness, hopelessness, or thoughts of suicide. This combination is particularly dangerous because the energy of mania can give someone the drive to act on depressive thoughts. Mixed episodes are diagnosed when at least three symptoms of the opposite mood state appear during a manic or depressive episode for the majority of its duration.
What Causes Bipolar Disorder
Bipolar disorder runs strongly in families. Twin studies estimate heritability at roughly 58% to 87%, with one large Swedish population study landing at about 60%. That means genetics accounts for a significant share of your risk, but it’s not the whole picture. Genome-wide studies looking at specific gene variants can only explain about 20% to 40% of the heritability, suggesting many genes each contribute a small amount of risk.
At the brain chemistry level, several signaling systems appear to be disrupted. Dopamine, the chemical messenger involved in motivation and reward, tends to be underactive during depressive episodes and overactive during mania. Byproducts of dopamine processing in spinal fluid reflect this: they drop during depression and spike during mania. Norepinephrine, the brain’s alertness and stress chemical, follows a similar pattern, with activity rising during manic episodes. Serotonin’s role is less clear-cut. Rather than tracking neatly with mood states, serotonin disruption seems more connected to impulsivity, aggression, and suicide risk.
Environmental triggers matter too. Major life stressors, disrupted sleep schedules, substance use, and even seasonal changes can set off episodes in someone who is biologically vulnerable.
Early Warning Signs of an Episode
Most episodes don’t arrive without warning. Research on prodromal symptoms (the subtle changes that appear before a full episode) has found that mood swings, depressed mood, racing thoughts, irritability, physical restlessness, and anxiety are the most common early signals. Some people develop highly personal warning signs: increased religiosity, listening to loud music, making decisions with unusual ease, or recalling past events obsessively.
Interestingly, sleep disturbances and expansive mood, the features most people associate with impending mania, don’t always show up reliably in studies as early warning signs. What does appear consistently are changes in sexual behavior, financial decisions, impaired judgment, and taking on an excessive number of projects. Learning your own pattern of early signals is one of the most practical tools for managing the condition long term.
How Bipolar Disorder Is Managed
Treatment for bipolar disorder is built around medication. The three main classes are mood stabilizers (lithium being the oldest and best studied), certain anti-seizure medications that also stabilize mood, and newer antipsychotic medications. The choice depends on the type and phase of illness. Newer antipsychotics appear especially helpful when manic and depressive symptoms mix together or when psychotic features are present. Most people need to stay on medication long term, as stopping often triggers relapse.
Therapy adds a meaningful layer on top of medication. One approach specifically designed for bipolar disorder is Interpersonal and Social Rhythm Therapy, or IPSRT. It’s built on the idea that stabilizing daily routines, especially sleep and wake times, social interactions, and meal schedules, helps regulate the body’s internal clock, which is often disrupted in bipolar disorder. A typical course involves 12 weekly sessions lasting about 90 minutes each. In controlled trials, people who received IPSRT alongside medication showed significant improvement in both depressive and manic symptoms, better overall functioning, stronger response to their medications, and longer periods of stable mood compared to those on medication alone.
Cognitive behavioral therapy adapted for bipolar disorder is another evidence-based option, focusing on identifying distorted thinking patterns during mood episodes and building strategies to prevent relapse.
Conditions That Often Overlap
Bipolar disorder rarely travels alone. About 1 in 4 people with a serious mental illness like bipolar disorder also has a substance use disorder. The relationship goes both ways: substance use can trigger or worsen episodes, and the impulsivity of mania makes risky substance use more likely. Cocaine, for example, has been shown to worsen bipolar symptoms and may accelerate the overall progression of the illness. Adolescent-onset bipolar disorder carries an even higher risk of developing substance problems compared to adult-onset.
Anxiety disorders are another frequent companion. The overlap complicates diagnosis because anxiety symptoms can look like hypomania (restlessness, racing thoughts, insomnia) or depression (withdrawal, avoidance, fatigue). ADHD, borderline personality disorder, and eating disorders also co-occur at higher-than-expected rates. When these conditions overlap, treatment becomes more complex and integrated approaches that address both issues simultaneously tend to produce better results than treating each one separately.