Causes

The exact cause of cluster headaches is unknown, but cluster headache patterns suggest that abnormalities in the body's biological clock (hypothalamus) play a role.

Unlike migraine and tension headache, cluster headache generally isn't associated with triggers, such as foods, hormonal changes or stress.

Once a cluster period begins, however, drinking alcohol may quickly trigger a splitting headache. For this reason, many people with cluster headache avoid alcohol during a cluster period.

Other possible triggers include the use of medications such as nitroglycerin, a drug used to treat heart disease.