Headaches 101

Headache Causes

You can thank your nerves for the pounding pain in your skull.
You can thank your nerves for the pounding pain in your skull.
David Freudenthal/Stock4B/Getty Images

Neither your brain tissue nor the bones of your skull contain pain-sensitive nerve endings, so what is the source of painful headaches? The answer has to do with the parts of your head that do have nerve endings. For example, the network of blood vessels that supply the base and surface of your brain are wrapped with sensitive nerve fibers able to fire off pain signals with a hair trigger. Pain-sensitive nerves can also be found in the scalp and in the muscles of your head, among other places.

Stress, muscular tension, inflammation and the constriction or dilation of blood vessels can all trigger the pain-sensitive endings of these nerves to transmit signals that activate the pain centers in your brain. Tension headaches, for example, can be caused by the chronic stretching of muscles that become tensed with stress or prolonged strain. One source of prolonged muscle tension is eyestrain -- a common cause of headache.

As with so many brain-related issues, doctors and scientists haven't fully uncovered all of the precise mechanisms and underlying causes of each type of headache. However, the experts have uncovered and explored many of the typical pathways involved in certain types of headaches. For example, migraine headaches are linked to changes in the flow of blood through vessels in the brain. As part of the migraine process, certain patterns of brain activity are believed to trigger the constriction of blood vessels, reducing the brain's oxygen supply. As part of a chain reaction, the blood vessels then dilate (widen) in response, and certain chemicals known to cause inflammation are released. The nerves coiled around the blood vessels then shoot off throbbing pain signals that pulse along with the blood flow. Some experts have suggested that in people prone to migraines, these blood vessels are overly reactive to certain conditions.

­While the precise biological mechanisms that cause headaches aren't fully understood, many common triggers, or factors that can lead to headaches, are associated with different headache types. For example, stress is the most commonly identified trigger for migraine headaches. Changes in hormone levels within the body are another known trigger, which is why three times more women than men experience migraines.

Experts know even less about the root cause of cluster headaches. Much of what is known about cluster headaches has to do with the common triggers. For example, alcohol (especially red wine) and cigarette smoke are two common factors that contribute to cluster headaches in an unknown way.

­­Because cluster headaches often occur around the same time each day, or during the same season each year, experts do know that cluster headaches are somehow related to the body's natural sleep/wake cycle and with seasonal changes. There's evidence that the hypothalamus, a part of your brain that acts as an internal biological clock of sorts, is involved in the onset of cluster headaches. Unlike tension headaches and migraines, cluster headaches are more common in men. The reason for this is unknown, but could be partially due to a higher link between males and certain risk factors, such as alcohol, smoking and physical exertion.

So we've taken a look at what causes the pain of headaches. Now how do you get rid of it?­