My doctor told me that I have cluster headaches. Cluster headaches start when people are about 30 years old, whereas migraines typically begin in the teens.
Cluster headaches derive their name from the observation that they occur in clusters.
During a cluster, headaches typically occur several times per day. Each headache usually occurs at the exact same time each day. The headaches often come at night. Each cluster lasts 1-2 months. In between clusters people have no headaches at all.