I totally agree with the coffee theory. I to am a coffee-a-holic, and
lack of caffeine does bring on the headache. Another most overlooked
reason is dehydration. During the day you might think you have hydrated
enough but more than likely you haven't. This will bring on the nightime
headache. I know back here in the east, if i don't drink at least 1- 2
ltr. bladder on a 15 mile day just after dinner i start getting the
beginnings of a headache. So now i make it a point to drink at least 2
ltrs. and probably more.