Prolonged or chronic headaches may also be caused by cluster headache
or Hemicrania continua, a rare type of chronic daily headache
. Cluster headaches also present with pain in the vicinity of the eye while hemicrania continua may vary in intensity but it never completely disappears. The precise causes and risk factors are unknown but medication overuse, stimulants such as caffeine, anxiety, sleep disorders and even obesity have been linked. Check with your doctor for proper evaluation.