Cluster headache patients describe the pain as burning. The pain is almost always felt on one side of the face. It can last for up to ninety minutes. Then it stops. But it often starts again later the same day. Eighty to ninety percent of cluster headache patients have pain over a number of days to a whole year. Pain-free periods separate these periods.

BARBARA KLEIN: The Cleveland Clinic says the cause of cluster headaches is in a brain area known as a trigeminal-autonomic reflex pathway. When the nerve is made active, it starts pain linked to cluster headaches. The nerve starts a process that makes one eye watery and red.

Studies have shown that activation of the trigeminal nerve may come from a part of the brain called the hypothalamus. The Cleveland Clinic says injections of the drug sumatriptan can help. Many other drugs could be used. For example, doctors say breathing oxygen also can help.

Thankfully, modern medicine has ways to treat almost all of our headaches.

(MUSIC)

STEVE EMBER: This program was written by Jerilyn Watson. Our producer was June Simms. I'm ­­­­­­­­­­­­­­­­­Steve Ember.

BARBARA KLEIN: And I'm Barbara Klein. Visit us at voaspecialenglish.com, where you can find transcripts and MP3s of our reports. Join us again next week for more news about science in Special English on the Voice of America.