Just to add to bonnet's details, cluster headaches can last from a few hours right up to weeks and occasionally months and are best described by an old G.P. of mine as 'Hell on earth'. They can be caused by jolts to the body (especially the head) - such physical knocks also serve to worsen the headache and prolong it too.

As with some migraines, light can affect the sufferer, as can noise too. My G.P. went on to say that medication is not, on the whole, considered all that effective, and the sufferer really has no choice but to sit out the attack.