You could have a burned out light bulb, or a plug undone, but there is no chance the light will work if the circuit is tripped, right?
Here's a fun fact for you. There is a circuit breaker for headaches. It's the very top part of your neck. All the different parts of a headache, whether its from your jaw, your sinuses, or your spouse, pass through the top 3 joints of your neck.
We can run into the chicken and the egg problem. Does a neck problem cause the headache or does a sinus/jaw/spouse/etc... problem cause the stress, that indirectly causes neck problems. Either way, the upper neck is involved in ALL headaches.
This comes from the most well respected, well known, and well researched spinal pain researcher, Nikolai Bokduk MD, PhD.
For example, you may feel like a headache starts in your stomach, guess what? That may be true, but those nerves junction at the base of your skull. ALL headaches have some form of junction in the upper part of your neck.
Once the circuit breaker is tripped, power doesn't work in your house. The only way that happens in your body is if you completely sever the nerves (ie...Christopher Reeves).
What you get is a slower form of function. The University of Colorado in Boulder found a potential loss of nerve function at about 60%. In chiropractic, we call this a subluxation complex. A loss of function coupled with possible misalignments.
To get back to headaches, Chan Gunn, MD. has written some of the best work on the effects of loss of nerve function. Essentially, the nerves become SUPER-sensitive.
If you are having more than 1 or 2 headaches a year, please tell me. Even if there is another problem with the jaw, sinuses, your eyes, or last nights bender, the upper neck still will need to be adjusted for the best relief possible.