HOW COME?: Why we get bags under eyes

Why do people get bags under their eyes? asks reader Corinne Badini. How come human beings blush? asks Gladys Reyes.

Swelling under the eyes can happen to anyone -- even sleep-deprived young children. But true eye "bags" become more of a feature as we age. Whether eye bags are a prominent feature or not depends on our genes. If one or both of our parents had eye bags, we're more likely to get them, too.

Swelling that is worst in the morning and diminishes by afternoon is often caused by how we sleep -- horizontally. Over the seven or eight hours we're lying flat, fluid accumulates in under-eye blood vessels.

But too little sleep can be a culprit too, along with salty foods, fluctuating hormones, and hot, humid weather. All can cause our bodies to retain water. In addition, allergies like hay fever can irritate and inflame eyes and surrounding skin, causing swelling made worse by rubbing itchy eyes.

As we get older, eye bags may last all day long. Why? Fat under the eye and above the cheekbone is held in place by a hammock of ligaments and muscle. As both weaken over time, the fat bulges forward. Meanwhile, the covering skin loses some elasticity, like the skin of a stretched-out balloon. The result: twin bags.

Home remedies can make eye bags less obvious. To immediately reduce swelling, hold a cold compress over each eye. Meanwhile, treat allergy symptoms. Avoid rubbing your eyes. Eat fewer salty foods. Get enough sleep. And to eliminate the two pillows under your eyes, try two pillows under your head. Sleeping with your head (or the head of the bed) slightly elevated allows gravity to redistribute fluids.

Unlike baggy eyes, which many of us don't experience until at least our 20s, blushing starts early. According to psychologists, toddlers as young as 15 months may get embarrassed when someone points at them. Soon, blushing follows.

Like sneezing, blushing is involuntary; it just happens. Blame the autonomic nervous system, or ANS, which automatically regulates functions like heart rate, pupil size, and the swelling (and shrinking) of blood vessels. Blushing is controlled by a part of the ANS called the sympathetic nervous system. The sympathetic nervous system prepares us for "fight or flight" in stressful situations, triggering the release of hormones like adrenaline.

Our cheeks are crisscrossed by a network of blood vessels located just under the surface of the skin. Signaled by hormones, the blood vessels suddenly expand. And redness spreads across the face, sometimes reaching the neck and ears.

Most human beings blush when they're uncomfortable or embarrassed. A reddened face is a way, like grimacing or grinning, we communicate feelings without words. Our fur- and feather-free faces are perfect for displaying every fleeting emotion -- even those we'd rather not reveal.

While you're not likely to encounter a hungry lion in the school hallway, you may feel a similar urge to flee when giving a presentation to your class. And so blood rushes to your face when you lose your place, stumble over familiar words, or fumble a fistful of papers, scattering them on the floor.