What causes normal mild headaches?

We are taught about headaches such as migraine, tension headaches, cluster headaches etc. But what causes the everyday normal dull headaches that don't fall into one of these more serious categories?

  • Are they muscular?
  • Are they caused by dehydration?
  • Is there another explanation?

I can't find this mentioned in any textbooks. Thanks!

Authored By Alex Catley on Thursday 3rd January 2013