Cluster headaches are a series of relatively short but extremely painful headaches every day for weeks or months at a time.
You get a cluster headache when a specific nerve pathway in the base of your brain is activated. That signal seems to come from a deeper part of the brain called the hypothalamus, where the “internal biological clock” that controls your sleep and wake cycles lives.
The nerve that’s affected, the trigeminal nerve, is responsible for sensations such as heat or pain in your face. It’s near your eye, and it branches up to your forehead, across your cheek, down your jaw line, and above your ear on the same side, too.
An underlying brain condition, such as a tumor or an aneurysm, won’t cause these headaches.