Take migraines," he says. "We know they're triggered by a number of things in the environment-sights, smells, even changes in the weather," Moods, too, can act as a catalyst: "Strong feelings, even ones people don't realize they have, can bring migraines on," says Jawer. He believes HSPs are unusually touchy to both emotional and tangible irritants-to mean-spirited comments as well as pollen or dander in the air.