The exact cause of a migraine is not known, but experts believe that they may be triggered by changes in the chemical balance in the brain. Research has shown that serotonin levels are lower during a migraine, which can cause the blood vessels in the brain to narrow (causing the aura symptoms) and then widen (causing the headache). It is not known why serotonin levels drop but a number of possible triggers have been identified; these include:
- Stress: this is usually related to emotional troubles such as relationship problems or tragic events, but may also be related to physical strain on the body caused by working too hard, not sleeping properly or travelling excessively.
- Environmental factors: environmental factors such as exposure to bright or artificial lighting, computer screens, changes in temperature and weather conditions, loud noises or particular chemicals, may trigger a migraine.
- Hormones: hormonal changes in the body may trigger migraines; this may explain why migraines are often common amongst pregnant women and women going through the menopause.
- Diet: certain foods (including dairy products, additives, caffeine and chocolate) may trigger migraines and dieting and skipping meals may also contribute to migraines. Many people find their migraines also develop as a result of drinking certain alcoholic drinks, including red wine.
- Hypertension: high blood pressure can contribute to migraines
- Eye strain: headaches and migraine scan be triggered as a result of the eyes being strained; this may result from a vision problem or spending long periods of time in front of television or computer screens.
- Medication: some types of medication, including sleeping tablets and the contraceptive pill may trigger migraines