Bussie, 1 glass of alcohol (beer) takes 1.5 hour to be "processed out of the body". Just takes your liver that time.
Because your liver is working on the alcohol it can't do (as much) other food etc. This will cause that... (man, I wont even try to come up with something as jafo or satans child will kill me

) well, atleast there is something arround your brain, little thin piece of skin, this will dry out and get tighter arround the brain, causing the headache.
So, drinking allot will help.
if its already too late, avoid contact with the sun or bright light... better yet, just keep your eyes shut