Causes

Though migraine causes aren't fully understood, genetics and environmental factors appear to play a role.

Changes in the brainstem and its interactions with the trigeminal nerve, a major pain pathway, might be involved. So might imbalances in brain chemicals — including serotonin, which helps regulate pain in your nervous system.

Researchers are studying the role of serotonin in migraines. Other neurotransmitters play a role in the pain of migraine, including calcitonin gene-related peptide (CGRP).

Migraine triggers

There are a number of migraine triggers, including:

• Hormonal changes in women. Fluctuations in estrogen, such as before or during menstrual periods, pregnancy and menopause, seem to trigger headaches in many women.

  Hormonal medications, such as oral contraceptives, also can worsen migraines. Some women, however, find that their migraines occur less often when taking these medications.

• Drinks. These include alcohol, especially wine, and too much caffeine, such as coffee.
• Stress. Stress at work or home can cause migraines.
• Sensory stimuli. Bright or flashing lights can induce migraines, as can loud sounds. Strong smells — such as perfume, paint thinner, secondhand smoke and others — trigger migraines in some people.
• Sleep changes. Missing sleep or getting too much sleep can trigger migraines in some people.
• Physical factors. Intense physical exertion, including sexual activity, might provoke migraines.
• Weather changes. A change of weather or barometric pressure can prompt a migraine.
• Medications. Oral contraceptives and vasodilators, such as nitroglycerin, can aggravate migraines.
• Foods. Aged cheeses and salty and processed foods might trigger migraines. So might skipping meals.
• Food additives. These include the sweetener aspartame and the preservative monosodium glutamate (MSG), found in many foods.