What happens in your brain during a migraine

A migraine is not just a bad headache — it is a neurological event, meaning something changes in how your brain and nervous system work. During a migraine, blood vessels in your brain constrict (tighten) and then dilate (widen), and the nerves around those vessels become inflamed. This combination causes the throbbing pain you feel, often on one side of your head.

The exact chain of events is still not fully understood, but researchers know that a chemical called serotonin plays a central role. Serotonin is a messenger that helps regulate pain signals in your brain. When serotonin levels drop suddenly, blood vessels react by narrowing, and then the surrounding nerves release inflammatory substances that cause swelling and pain.

This is why migraine medications often work by raising serotonin levels or blocking the inflammatory response — they interrupt the chain at different points. Understanding that a migraine is a physical process in your brain, not something you are imagining or bringing on yourself, is important for how you approach treatment.

Key Takeaways

  • Migraines involve changes in blood vessel size and nerve inflammation in your brain, triggered by a drop in serotonin levels.
  • Common triggers include hormonal changes, certain foods, stress, sleep disruption, and environmental factors like bright light or strong smells.
  • Some people have a genetic predisposition to migraines, meaning the condition runs in families and your brain is wired to react more sensitively to triggers.
  • Identifying your personal triggers through a migraine diary helps you avoid them or prepare for a migraine when avoidance is not possible.
  • Migraine patterns change over time and can be influenced by age, hormones, stress levels, and other life circumstances.

Why some people are more prone to migraines than others

Not everyone who encounters a migraine trigger will have a migraine. Some people's brains are simply wired to be more reactive. This tendency often runs in families — if your parents or siblings have migraines, your risk is higher. Researchers believe this is partly genetic, meaning you inherit a sensitivity to the chemical and physical changes that trigger a migraine.

Women are about three times more likely to have migraines than men, especially during their reproductive years. This difference is largely due to hormonal fluctuations. Many women notice migraines cluster around their menstrual cycle, when estrogen levels drop. Pregnancy, hormonal birth control, and menopause can all shift migraine patterns.

Age also matters. Migraines often start in the teenage years or early adulthood, peak in the 30s and 40s, and may decrease later in life. However, some people develop migraines for the first time in middle age or experience a change in how often they occur.

Common triggers that set off a migraine

A trigger is something that starts the migraine process in your brain. The same trigger does not affect everyone — your triggers are personal to you. Keeping track of when your migraines happen and what was happening beforehand (called a migraine diary) helps you spot your own patterns.

Hormonal triggers are among the most consistent. For women, these include menstrual cycles, hormonal birth control, and hormone replacement therapy. Food and drink triggers vary widely but commonly include aged cheeses, cured meats, chocolate, caffeine (especially sudden changes in intake), alcohol, and foods with the additive MSG. Environmental triggers include bright or flickering light, loud noise, strong smells, and changes in weather or barometric pressure.

Lifestyle triggers are equally important. Skipping meals, dehydration, poor sleep, too much sleep, and sudden changes in routine can all bring on a migraine. Stress and emotional triggers are common — not just stress itself, but sometimes the relief after stress ends. Physical exertion, especially if you are not used to it, can trigger a migraine in some people.

Overusing migraine medication (taking it more than 10 to 15 days per month) can paradoxically cause more frequent migraines, a condition called medication overuse headache. This is why doctors recommend using acute migraine medication sparingly and considering preventive treatment if migraines are frequent.

How your nervous system becomes sensitized to triggers

Over time, repeated exposure to triggers can make your nervous system more reactive — a process called sensitization. Your brain essentially becomes primed to respond to smaller and smaller triggers. This is why someone who has frequent migraines may find that things that never bothered them before now set one off.

Stress is a good example. A single stressful day might not cause a migraine, but weeks of ongoing stress can lower your threshold, so that a minor annoyance triggers one. Similarly, if you regularly skip breakfast, your brain adapts to expect that pattern, and breaking it can trigger a migraine. The nervous system is learning and adjusting based on what it experiences.

This sensitization is also why preventing migraines — by avoiding triggers, managing stress, maintaining regular sleep, and staying hydrated — can be as important as treating them once they start. Reducing how often your nervous system is triggered can actually reset your sensitivity over time.

The role of inflammation and nerve activity

When a migraine begins, the trigeminal nerve (a major nerve in your face and head) becomes activated and inflamed. This nerve releases substances that cause blood vessels to swell and surrounding tissues to become inflamed. The inflammation itself sends pain signals to your brain, which you feel as the migraine headache.

This inflammatory response is why some migraine medications are anti-inflammatory — they reduce the swelling around nerves and blood vessels. Other medications work on the nerve itself, blocking the release of inflammatory substances. Understanding that inflammation is part of the process helps explain why rest, ice, and anti-inflammatory medication can sometimes help, and why the pain often builds gradually rather than hitting all at once.

The inflammation can also explain why a migraine often comes with other symptoms beyond headache: nausea and vomiting (from nerve irritation affecting your stomach), sensitivity to light and sound (from heightened nerve sensitivity), and sometimes vision changes or tingling (from nerve activity spreading across your brain).

How hormones influence migraine patterns

Hormones are powerful regulators of serotonin and blood vessel function, which is why hormonal changes are such strong migraine triggers. The most obvious example is the menstrual cycle. Many women have migraines that cluster in the days before their period starts or during the first few days of bleeding, when estrogen levels drop sharply.

Hormonal birth control can either improve or worsen migraines, depending on the person and the type of contraceptive. Some women find that continuous-dose pills (which skip the hormone-free week) reduce migraines, while others do better with traditional cycling pills. Pregnancy often changes migraine patterns — some women find their migraines improve, while others experience more frequent ones.

Menopause brings another shift. The hormonal fluctuations during perimenopause (the years leading up to menopause) can make migraines worse before they improve. After menopause, when hormone levels stabilize at a lower level, many women find their migraines decrease or stop entirely.

Why migraines change over your lifetime

Migraines are not static. The frequency, severity, and even the triggers can shift as you age, as your life circumstances change, and as your body changes. A migraine pattern that has been consistent for years can suddenly become more or less frequent, or new symptoms can appear.

Life stress, major health changes, medication changes, and hormonal shifts all influence migraine patterns. Someone who had frequent migraines in their 20s might find them nearly disappear in their 40s, or vice versa. New triggers can emerge — a food that never bothered you before might start triggering migraines, or a longtime trigger might stop affecting you.

This is why it is useful to revisit your migraine diary periodically and talk with your doctor about changes you notice. What worked to prevent or treat migraines five years ago might need adjustment now. Recognizing that migraine patterns evolve helps you stay flexible in how you manage them.

Frequently Asked Questions

Are migraines caused by something I am doing wrong?

No. Migraines are a neurological condition, not a result of weakness or poor choices. While triggers like stress or skipped meals can set one off, having migraines is not your fault. Many people with migraines are doing everything right and still experience them because of their brain chemistry and genetics.

Can migraines be caused by a brain tumor or serious illness?

Migraines themselves are not caused by tumors or serious illness. However, a sudden change in your migraine pattern — new type of headache, worse severity, different symptoms, or migraines that do not respond to your usual treatment — should be evaluated by a doctor to rule out other conditions.

Why do migraines run in families?

Migraines have a genetic component, meaning you can inherit a tendency for your brain to be more reactive to triggers. If both your parents have migraines, your risk is higher than if neither does. However, genetics is not destiny — having a family history does not may provide you will have migraines.

Can stress alone cause a migraine, or do I need a trigger too?

Stress can be a trigger on its own, but migraines usually result from a combination of factors. You might handle stress fine one week but have a migraine the next week when stress combines with poor sleep or a hormonal change. This is why tracking multiple factors in a migraine diary is more useful than focusing on just one.

If I avoid all my triggers, will I never have a migraine?

For some people, trigger avoidance significantly reduces migraines. For others, migraines happen even when triggers are avoided, because the underlying brain chemistry is reactive enough to fire on its own. This is why some people benefit from preventive medication even when they are managing triggers well.