What Happens in Your Brain During a Migraine

A migraine is not simply a bad headache—it is a neurological event involving changes in blood vessel activity, nerve signaling, and brain chemistry. The exact sequence is still being mapped, but researchers have identified a pattern: a wave of electrical activity spreads across the brain's surface, followed by changes in blood flow and the release of inflammatory chemicals around nerves and blood vessels. This cascade of events produces the throbbing pain, sensitivity to light and sound, and sometimes nausea that define a migraine attack.

The trigeminal nerve, which carries sensation from your face to your brain, plays a central role. During a migraine, this nerve becomes irritated and releases substances that inflame the tissues around it. Blood vessels in the brain and scalp dilate (widen), which contributes to the pain. The whole process can last hours or even days, and the exact trigger—why it starts in the first place—varies from person to person.

Key Takeaways

  • Migraines involve a cascade of brain activity, nerve irritation, and blood vessel changes rather than a simple blood vessel problem.
  • The trigeminal nerve releases inflammatory chemicals that sensitize pain pathways and cause the characteristic throbbing pain.
  • Genetics play a major role—if both parents have migraines, your risk is around 70 percent; if one parent has them, your risk is around 50 percent.
  • Common triggers include hormonal changes, certain foods, sleep disruption, stress, and environmental factors, but triggers vary widely between individuals.
  • Understanding your personal pattern of triggers and early warning signs can help you recognize when a migraine is starting.

Why Genetics Make You Vulnerable to Migraines

Migraines run in families because they involve inherited differences in how your brain processes pain signals and regulates certain chemicals. If both your parents have migraines, your risk is approximately 70 percent. If one parent has them, your risk is around 50 percent. If neither parent has migraines, your risk is still about 10 percent, meaning genetics is not the only factor.

The genetic component does not mean you will definitely get migraines—it means your nervous system is wired in a way that makes migraines more likely under the right conditions. Researchers have identified several genes associated with migraine susceptibility, many of them involved in how brain cells handle calcium, potassium, and neurotransmitters like serotonin. These genes affect how easily your brain's electrical activity can spread and how sensitive your pain pathways become.

Common Triggers That Set Off an Attack

A trigger is something that increases the likelihood a migraine will start, though the same trigger does not always cause one and not everyone with migraines responds to the same triggers. Hormonal changes are among the most common: many women experience migraines around their menstrual cycle, during pregnancy, or when taking hormonal birth control. Estrogen fluctuation appears to lower the threshold at which a migraine begins.

Food and drink triggers vary widely but commonly include aged cheeses, cured meats, chocolate, caffeine (both consuming it and withdrawing from it), alcohol—especially red wine and beer—and foods containing monosodium glutamate (MSG). Skipping meals or fasting can also trigger migraines in some people. Sleep disruption, whether too little or too much, is a frequent culprit. Stress itself does not always trigger a migraine, but the release of stress—the relaxation after a tense period—sometimes does.

Environmental and sensory triggers include bright or flickering lights, loud noises, strong smells, and changes in weather or barometric pressure. Physical exertion, dehydration, and sudden changes in caffeine intake can also set one off. Keeping a migraine diary—noting when attacks occur and what happened in the hours before—helps you identify which triggers matter for you specifically.

How Serotonin and Other Brain Chemicals Play a Role

Serotonin is a neurotransmitter that helps regulate mood, sleep, and pain perception. People with migraines often have abnormal serotonin levels or sensitivity to serotonin changes. During the early stages of a migraine, serotonin levels drop, which may trigger the initial wave of brain activity. Later, serotonin levels rise, which can contribute to the pain phase.

Other chemicals involved include dopamine, glutamate, and calcitonin gene-related peptide (CGRP). CGRP is particularly important: it is released during a migraine and causes blood vessels to dilate and nerves to become more sensitive. This discovery led to a new class of migraine treatments called CGRP antagonists, which block this chemical and have proven effective for many people. Understanding these chemical pathways has shifted migraine treatment from simply trying to constrict blood vessels to targeting the underlying nerve and chemical processes.

Why Women Experience More Migraines Than Men

Women are roughly twice as likely as men to have migraines, and this difference is largely hormonal. Estrogen fluctuations trigger migraines in many women, which is why migraines often worsen around menstruation, improve during pregnancy (though not always), and may change when hormonal birth control is started or stopped.

The relationship between estrogen and migraines is complex: it is not the level of estrogen itself but the change in estrogen that matters. A sudden drop in estrogen—such as the drop that occurs just before menstruation—is more likely to trigger a migraine than a stable high or low level. Some women find that using continuous hormonal birth control (skipping the placebo week) reduces migraine frequency by preventing the monthly estrogen dip. Others find that hormonal birth control makes migraines worse. This variation is why tracking your migraine pattern in relation to your menstrual cycle can be informative.

Age and How Migraines Change Over Time

Migraines most commonly begin in the teenage years or early adulthood, though they can start at any age. The peak frequency is usually in the 30s and 40s. In many people, migraine frequency and severity decrease with age, particularly after age 50, though some people continue to have frequent migraines throughout life.

Hormonal changes across the lifespan affect migraine patterns. Menopause often brings changes in migraine frequency—some women see improvement, others see worsening, and some see no change. Hormone replacement therapy during menopause can also shift migraine patterns. Men's migraines tend to remain more stable across the lifespan, since they do not experience the same hormonal fluctuations.

When Migraines Signal Something Else

Most migraines are primary headaches, meaning they are the condition itself rather than a symptom of something else. However, a change in your migraine pattern—new severity, new frequency, a different type of aura, or migraines that feel different from your usual ones—warrants evaluation by a healthcare provider. These changes can occasionally signal a secondary condition such as high blood pressure, infection, or structural changes in the brain.

Migraines with aura (visual disturbances, tingling, or speech difficulty before the headache starts) carry a slightly higher stroke risk than migraines without aura, particularly in women who smoke or use hormonal birth control. This does not mean migraines with aura will cause a stroke, but it is a reason to discuss your migraine type and risk factors with a doctor, especially if you are considering hormonal contraception.

Frequently Asked Questions

Can stress cause migraines?

Stress can lower your migraine threshold, making an attack more likely, but the migraine often occurs during the relaxation phase after stress ends rather than during the stressful period itself. This is called a "letdown migraine." Stress management may reduce frequency, but it is not a complete solution since other triggers also matter.

Why do some migraines have aura and others don't?

Aura occurs when the wave of electrical activity across your brain spreads to areas that process vision, sensation, or speech, producing visual flashes, blind spots, tingling, or difficulty speaking before the headache begins. Not all migraines trigger this wave in those specific brain regions, so some migraines lack aura. The same person may experience both types.

Does caffeine help or trigger migraines?

Caffeine can work both ways. During a migraine, caffeine narrows blood vessels and can enhance pain relief medication, which is why it appears in some migraine treatments. However, regular caffeine use followed by sudden withdrawal can trigger a migraine. Consistency matters more than the amount—sudden changes in your caffeine intake are more likely to cause problems than a stable routine.

Can weather changes really trigger migraines?

Yes, for some people. Drops in barometric pressure, changes in humidity, and temperature shifts can trigger migraines, possibly by affecting fluid pressure in the inner ear or by triggering changes in serotonin. Not everyone is sensitive to weather changes, and tracking your migraines against weather patterns can help you determine whether this applies to you.

If I have migraines, will my children have them?

There is a significant genetic component, so your children have a higher risk than the general population, but having a parent with migraines does not may provide they will develop them. Environmental factors, triggers, and other life circumstances also play a role. About 50 percent of children with one parent who has migraines will develop migraines themselves.