This is my own coined term; it’s natural to get a headache in certain circumstances. Mild dehydration, hunger, cold, lack of sleep… anything that upsets the body can be responsible. If you break your toe & hobble around, your head will hurt. Uncomfortable from constipation? You get the idea.
Anything that gets on our nerves, interferes with concentration, can cause a headache. Too much concentration can also cause a headache. Usually the cause is obvious, but people don’t realize it.