The infrared light energy releases nitric oxide from hemoglobin and endothelial cells. Nitric oxide, "the molecule of life," is a signaling molecule that relaxes smooth muscle cells found in the arteries, veins, and lymph vessels. When these muscles relax, the vessels dilate, thus allowing increased circulation. Visualize the difference in diameter between a straw and a hose – that's an example of vasodilation.
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