Cluster Headaches Cluster headaches occur in groups, or clusters, and individual attacks last one to three hours on average. They may occur every other day—or several times a day. The Cluster Headache: Just Like Clockwork Cluster headaches -- called "cluster" because of their pattern of striking in groups or clusters -- hit at the same time of day for a period of weeks or months, then vanish as suddenly and as mysteriously as they appeared. Tension Headaches Tension headaches are typically a steady ache, rather than a throbbing one, and affect both sides of the head. Stress or muscle tension is often the cause. Help for Tension Headaches Almost everyone has a tension headache from time to time. These headaches aren’t caused by disease. They are so common they are considered to be “normal” headaches.