Maybe they are, but I'd say that the corresponding inability to function outweighs whatever benefit they might afford.
My headaches have subsided considerably in the past year. It was, in fact, right at a year ago that I was having severe, crushing headaches that were later found to be caused by skyrocketing blood pressure. They never figured out why my BP shot up like that, but at least it's now well controlled and stable. I say stable; it doesn't shoot up high anymore. Occasionally it dips low enough to cause me to faint, but that tends to happen only during medical procedures (mine or my children's). I have no idea why.