Headaches are very common and can take many forms, from mild to debilitating and lasting minutes to days. When your skull is in pain, it’s easy to think that your brain tissue itself must be injured. But that’s not likely.
Ironically, the brain senses pain throughout the body, but it doesn’t have pain receptors of its own. Then why do headaches hurt?
Headaches can result from an underlying medical condition, such as B. swollen sinuses, low blood sugar or a head injury. But, by and large, most headaches are due to “referred pain,” meaning you feel the pain in a different place than where it’s actually occurring. dr Charles Clarke (opens in new tab), a neurologist and headache specialist at Vanderbilt Health in Tennessee, told Live Science. It’s similar to how a herniated disc in the back can cause sciatica, a pain in the leg. With most headaches, a problem elsewhere in the body — like the jaw, shoulders and neck — causes pain in the muscles and nerves around the brain, he said.
Related: Why do so many people have back pain?
Take tension headaches out loud World Health Organization (opens in new tab), are the most common form of recurring headaches. Tension headaches often present as pain in the muscles above the head or forehead, where a sweatband or headband would sit, Clarke said. The pain is caused by tight muscles in the face, neck and scalp and can be related to stress National Institute of Health (opens in new tab) (NIH). But the headache and tightening of the cranial muscles may be secondary to another stress response, like stiff shoulders or a clenched jaw, Clarke said.
According to the NIH, pain-sensitive nerves in the muscles and blood vessels in the head, neck, and face can be triggered by various processes, such as dilated blood vessels, stress, or muscle tension. Once activated, these nerves send messages to the brain, but it can feel like the pain is coming from deep within the brain tissue.
Migraine is another kind of headache, although technically headaches are just a symptom of the neurological disorder. Migraine headaches can be felt in different ways and at different locations: deep pain, superficial pain; the back, left or right of the head; or behind the eyes. What differentiates migraines, Clarke said, is their severity.
Migraine pain is more intense than other headaches and can last longer. The disorder is often genetic and can cause additional symptoms, such as nausea. The underlying causes of migraines aren’t fully understood, but one theory suggests that the pain is linked to the trigeminal nerve, the sensory nerve for the head and face; and the dura, the protective layer of the brain where blood vessels expand and contract.
One possible explanation for migraine pain is that an electrical event in the brain stimulates the trigeminal nerve pathways and triggers an inflammatory response (opens in new tab). Inflammation spreads through the dural blood vessels and the trigeminal nerve fibers send signals back to the dural nerves brainstem (opens in new tab). The inflammation then spreads to pain-sensitive meninges – protective tissue around the brain – and triggers headaches.
This cascade of inflamed blood vessels and irritated nerves is “a fire burning out of control,” Clarke said. It’s like a feedback loop that becomes more and more irritated, causing the experience of a migraine to build, he said. For this reason, many migraine treatments work better when used earlier.
While the relationships between pain in the body and headaches are well understood, the mechanisms that cause headaches are still not fully understood, Clarke said. But the good news is that “we’re very good at handling these,” he said. For example, lifestyle changes, like practicing yoga; over-the-counter medications such as ibuprofen and aspirin; and prescription medications for more severe headache disorders can do a lot to reduce the severity and frequency of headaches.
“When people need help [with headaches] we can often do them much better,” Clarke said.