Raynaud’s is a nitric oxide problem. And nitric oxide problems are endothelial problems. And endothelial problems are whole-body problems. NO is what keeps your blood vessels open. When it’s low, the tiniest vessels in your fingers and toes clamp down first. Cold, stress, or even mild temperature changes trigger an exaggerated response because there’s not enough NO to balance the sympathetic nervous system. That’s why you see the classic white → blue → red colour changes. The reason it matters: