What causes 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 chemicals in the brain called neurotransmitters become imbalanced. This process causes the throbbing pain, sensitivity to light and sound, and sometimes nausea that you feel.

Scientists do not yet fully understand why this happens in some people and not others, but they know it involves your genes, your environment, and specific triggers. If your parents had migraines, you are more likely to have them too. But genetics alone does not cause a migraine—you also need a trigger, which is something that sets off the chain reaction in your brain.

Key Takeaways

  • Migraines happen when blood vessels in your brain tighten and then widen, combined with chemical imbalances that cause pain and sensitivity to light and sound.
  • Your genes make you more likely to have migraines, but a trigger—something in your environment or habits—has to start the process.
  • Common triggers include hormonal changes, skipped meals, sleep disruption, stress, and certain foods or drinks like caffeine and alcohol.
  • Keeping a migraine diary helps you spot your personal triggers so you can avoid them or prepare for them.
  • Knowing your triggers is the first step to preventing migraines before they start.

Hormonal triggers in women

For many women, migraines are tied to hormonal changes. Fluctuations in estrogen—the hormone that rises and falls during your menstrual cycle—can trigger a migraine. Some women get migraines only around the time of their period, while others notice them at other points in their cycle. Pregnancy, menopause, and hormonal birth control can all change your migraine pattern.

If you notice your migraines follow your menstrual cycle, tell your doctor. They may suggest timing your preventive medication around your cycle, or they may recommend a different form of birth control that keeps hormone levels more stable. Tracking when your migraines occur relative to your period is useful information to share.

Food, drink, and meal timing

Certain foods and drinks are known migraine triggers for many people. Caffeine is one of the most common—both consuming it and withdrawing from it can trigger a migraine. Alcohol, especially red wine and beer, triggers migraines in some people. Aged cheeses, processed meats, chocolate, and foods with the additive monosodium glutamate (MSG) are other frequent culprits.

Skipping meals or going too long without eating can also trigger a migraine. When your blood sugar drops, it can set off the chain reaction in your brain. Eating regular meals and staying hydrated throughout the day may help prevent migraines from starting. If you suspect a food is triggering your migraines, your doctor can help you test this safely by removing it for a few weeks and then reintroducing it.

Sleep, stress, and sensory overload

Disrupted sleep is one of the strongest migraine triggers. This includes sleeping too little, sleeping too much, or having an irregular sleep schedule. Even a single night of poor sleep can trigger a migraine the next day. Stress and emotional tension also trigger migraines in many people—sometimes during the stressful period itself, and sometimes afterward when you finally relax.

Sensory triggers matter too. Bright lights, loud noises, strong smells, and flickering screens can all set off a migraine. If you work in a bright office or spend long hours at a computer, these environmental factors may be contributing. Some people find that reducing screen time, adjusting lighting, or using blue-light glasses helps prevent migraines.

Weather and environmental changes

Changes in barometric pressure—the weight of air in the atmosphere—trigger migraines in some people. You might notice migraines starting when a storm is moving in, or when you travel to a higher altitude. Temperature extremes, humidity, and seasonal changes can also play a role.

While you cannot control the weather, knowing that it is a trigger for you helps you prepare. If you know a storm is coming and you are prone to weather-related migraines, you might take preventive medication early or avoid other triggers that day. Staying hydrated and maintaining your regular sleep schedule during weather changes may also help.

How to track your triggers

The best way to understand what causes your migraines is to keep a migraine diary. Each time you have a migraine, write down the date, time it started, how long it lasted, and how severe it was. Then note what you ate and drank in the 24 hours before, how much sleep you got, your stress level, where you were, and anything else unusual that day.

After tracking migraines for two to three months, patterns usually emerge. You might notice that migraines always follow a certain food, or that they cluster around your period, or that they happen after stressful work weeks. Once you identify your triggers, you can work with your doctor to avoid them or to take preventive medication on days when you know you will be exposed to a trigger.

When triggers overlap

One trigger alone might not cause a migraine, but two or three triggers together often will. For example, you might tolerate caffeine withdrawal on a normal day, but if you also skipped breakfast and did not sleep well, that combination pushes you over the threshold into a migraine. This is why tracking multiple factors in your diary matters—it helps you see the whole picture.

Understanding this also means you do not have to eliminate every possible trigger. If you know that stress plus poor sleep triggers your migraines, you can focus on protecting your sleep on stressful days rather than trying to avoid stress entirely, which is usually impossible. Your doctor can help you prioritize which triggers to target first.

Frequently Asked Questions

Can migraines be caused by something serious like a brain tumor?

Most migraines are not caused by serious conditions. However, if your migraines are new, getting worse, or different from your usual pattern, or if you have other symptoms like weakness, vision changes, or fever, see a doctor. They can examine you and order imaging if needed to rule out other causes.

Why do I get migraines even when I avoid my triggers?

Triggers are not always obvious, and some people have multiple triggers that interact in complex ways. You might also have triggers you have not identified yet. Keeping a detailed diary over several months often reveals patterns that are not immediately clear. Your doctor can also help you spot triggers you might be missing.

Does stress always cause migraines?

Stress is a common trigger, but not everyone with migraines is triggered by stress, and not every stressful day causes a migraine. Some people are triggered by the stress itself, others by the letdown after stress ends. If stress seems to trigger your migraines, your doctor may suggest stress-reduction techniques or preventive medication.

Can caffeine prevent migraines or only trigger them?

Caffeine is complicated—it can both trigger and relieve migraines depending on the person and the situation. Some migraine medications include caffeine because it can help the medicine work better. But regular caffeine use followed by withdrawal is a strong trigger for many people. Talk to your doctor about whether caffeine helps or hurts your migraines.

If I have migraines, will my children have them too?

Migraines run in families, so your children have a higher chance of having them than children whose parents do not have migraines. However, having the genetic tendency does not mean they will definitely get migraines—they would also need to encounter triggers. You cannot prevent this, but you can help them recognize early signs and seek treatment if migraines develop.