Migraines are severe, throbbing headaches that may or may not be accompanied by nausea, visual disturbances and other symptoms. Any number of things can trigger a migraine in a susceptible individual, including, allergies, stress, emotional or hormonal changes and sleep depravation. Low blood sugar is frequently associated with migraine. Virtually everyone gets a headache at some time. Headaches are as common as the common cold and flu and are generally caused by stress, tension, anxiety, allergies, nutritional deficiencies, coffee consumption, eyestrain and hunger to name but a few. Headache experts estimate that about ninety percent of all headaches are tension headaches.