I have weekend-inducing headaches pretty reliably (they are preventable/treatable with ibuprofen thankfully) to the point I sometimes take a lower dose of ibupr

I have weekend-inducing headaches pretty reliably (they are preventable/treatable with ibuprofen thankfully) to the point I sometimes take a lower dose of ibuprofen on Friday night to try to ward them off. Anyone know the mechanism? I think I've isolated away caffeine dosage changes, sleep schedule changes... It's almost like the work schedule and "it's go time" wards off / triggers some survivalist "don't get a headache now or you die". I also notice I don't get headaches when I have common colds, when the additional sinus stress would theoretically cause more. My headaches seem to be related to the sinuses, although they have aspects of tension (jaw stiffness and base of skull) as well as vomiting and sensory sensistivity that is kinda migraine-ish, but not. I also have seen, back when I sometimes did ironman triathlons, that headaches reduced when I got into really good shape, probably around half-ironman shape.