Stress and MCAS often do correlate with photosensitivity, and if you have MCAS all your allergy-like reactions are going to be increased by stress, true. I've found that if my exposure to sunlight is very regular I do pretty well, though. Of course, if stress leads you to take tricyclics, they can cause photosensitivity as well. I would not discount the possibility that regular sun exposure reduces stress by boosting the immune system (not just by Vitamin D) however: https://www.labroots.com/trending/health-and-medicine/4846/b...