Blushing is a process, usually involuntary, that occurs for psychological reasons when we face emotional stress from compliments, shame, shyness, passion, anger, or even romantic factors. In cases where the rash "is redder than usual", we are dealing with anxiety, social or otherwise.
When faced with such situations, our body releases epinephrine (adrenaline), causing us to experience real physiological symptoms. In addition to increasing the heart rate, affecting the digestive system, or even reducing pain, epinephrine also acts on some blood vessels. It causes blood vessels to dilate, improving blood and oxygen circulation to specific areas of the body, in this case, the face. While the blood vessels dilate, the cheeks redden and you get that cute look, of an innocent girl/boy.
So next time, before you feel embarrassed that you're blushing, remember what work your body is doing and how much adrenaline it's releasing.
