Headache is certainly one of the most common come pain complaints that afflicts humans. There are many, many causes. Stress - the so-called tension headache. It often turns out that tension headaches are more complex, but certainly people under a lot of stress or pressure often experience headaches. Migraines are very, very common. This is essentially a malfunction of the nerves in the surface of the brain and the cortex of the brain, and at times the malfunction can even be observed or witnessed by the patient because they may get what we call an aura - flashing lights in their vision or waves of out-of-focus vision. Sometimes they get other sensations that are a sign that the nervous system is malfunctioning and that often will trigger a cascade effect that will lead to the patient having a fairly severe headache.