Why Do We Blush?

You have been practicing your solo for the school talent show for months. You step out on stage as the applause of your schoolmates fills the air. Butterflies fill your stomach. The music begins, and you confidently open your mouth for the first note. But instead of a beautiful melody, your voice cracks—and out comes a squeak! Even as you recover and continue with the rest of the song as planned, you can feel from the heat on your cheeks that your face has turned bright red.

Have you ever wondered why you blush in situations of embarrassment, guilt, or even at a compliment?

To begin, let’s first look at the physiology of blushing to see what happens in our bodies that causes the redness in our faces. Basically, an involuntary reaction of our sympathetic nervous system causes the blood vessels in our face to dilate. This increases blood flow to the area, resulting in a color that ranges from light pink to dark red. Because it is involuntary, it is something we cannot control, despite our best efforts.

Now, let’s take a more detailed look. Blushing begins with an emotion—usually one associated with self-consciousness. Our adrenal glands produce adrenaline that binds to the surface of responsive cells. This causes an enzyme called adenylyl cyclase to activate, which, in turn, causes the level of cyclic AMP to increase. Cyclic AMP is a messenger molecule that transmits the adrenaline signal within the cell. This increase in cyclic AMP levels directly causes the dilation of blood vessels.

To exacerbate things is the fact that the areas of our body that blush are different in structure than other areas. Blushing regions such as our cheeks have more capillaries and blood vessels in comparison to other regions of the body. And, the vessels themselves in our cheeks are also wider in diameter and closer to the surface. All these factors combine to enhance the effect of the blood flow into a warm rosy flush.

Despite now knowing what happens, you may still be asking why everyone blushes. Well, sadly, the answer is no one really knows. Very little scientific study has been done, and the few studies that have been conducted are from a psychological perspective.

However, the few findings there are have yielded some interesting facts. For example, it looks as though blushing first appears in children of kindergarten age, when interaction with others produces a social awareness for the first time. Then, through adolescence, blushing reaches its highest level as teenagers go through a period of being very self-conscious. As we get older, blushing seems to dissipate. This happens because adults become less self-conscious with age and experience, and the stimulation of facial blood vessels decreases with age.

In addition to age, various other social factors also contribute to blushing. It appears, for example, that women tend to blush more than men—especially when related to compliments and modesty. Cultural background also plays a part, as those of European descent tend to blush more than those of Asian descent—despite no physiological differences. Even those with very dark skin can blush deeply.

So, the next time you find yourself embarrassed, and feel the heat rising rapidly in your cheeks, try to take comfort in the fact that you have no control over this involuntary reaction—and everyone else goes through the same process at one time or another!

Source: HHMI Ask a Scientist (www.hhmi.org/askascientist/index.html)