What causes tension headaches in teens?

While there are several kinds of headaches, including migraines, the most common headache related to stress is called a tension headache. It used to be thought that tension headaches came from muscle tension, but it’s now believed these headaches occur when fluctuations in the neurotransmitter serotonin and natural pain relievers called endorphins activate pain pathways in the brain. When serotonin levels drop, the trigeminal nerve, which comes from the brain and divides into three branches that cover the face--releases substances that cause blood vessels to become dilated and inflamed (see adjacent illustration). This inflammation causes steady pain--the feeling that your head is being squeezed in a vise--as does irritation of the nerve itself.