I get migranes at least 2x a month.. puts me out of action for at least 24 hours (basically get incapacitated). I get warnings by not being able to see objects directly in front of me (they call them aura's).. thats when I know it's going to get bad.. my fix is to put a pair of really dark oxy-acetylene goggles on, and just sit quietly for a few hours.. It stuffs me around pretty badly, have had chronic fatigue for the last few years because of it.. so sometimes its really hard to even get going.
I think the main cause for me is stress + sometimes light at the wrong angle sets it off too..