A cluster headache is one-sided head pain that may involve tearing of the eyes and a stuffy nose. The headaches occur repeatedly every day at the same time for several weeks and then goes away. A cluster headache begins as a severe, sudden headache. The headache most commonly strikes 2 to 3 hours after falling asleep, usually during the dreaming (rapid eye movement, or REM) phase. The physicians at AZ Pain Centers have great success in treating Cluster Headache sufferers. Give us a call today and let us help.