Researchers are still investigating the exact cause of migraines, but there's some evidence that this type of headache occurs as a response to changing brain chemicals. Serotonin, a chemical that helps nerve cells communicate with each other, plays a role in regulating pain. When serotonin levels decrease during times of anxiety, stress and depression, migraine headaches are more likely to occur.
Constant stress and anxiety also make it difficult for patients with migraines to get restful sleep and engage in other self-care activities, further increasing the release of stress hormones and risk of developing a migraine or recurrent headache. Surprisingly, relaxing isn't a surefire way to prevent chronic migraines. In some people, a period of relaxation after a period of intense stress creates a "letdown effect," triggering head pain and other migraine symptoms.