Why do bags form under your eyes when you're tired?

It’s a flag to others to tell you to get more sleep.

Well, Scientific American puts it this way:

“As we age, fat comes out of the space enclosed by the eye socket, called the orbit, and forms a puffy area under the eye. This fatty tissue can fill with water. Thus, it becomes more noticeable when water is retained, which can occur for a variety of reasons including eating too much salt, lying flat in bed, not getting enough sleep, allergies, and monthly hormonal changes. Dark circles under the eye occur for several reasons: The skin there is much thinner than skin elsewhere on the body and becomes looser under the eyes as we age. This very thin skin also sits on top of underlying purple muscle and blood vessels and thus appears darker. In addition, some people have hereditary pigmentation in this area.”

It has nothing to do with blood rushing anywhere. It has more to do with puffiness from water retention related to allergies, lack of sleep, aging, genetics, how you sleep, and how much salt you eat.

The purple color is just due to the fact that the skin there is very thin so the underlying blood and muscles show through. When you retain water the skin is stretched so it is even thinner and the purple color is even darker.

good question…i also am curious about this

I’ve heard that used (but cool) tea bags are supposed to help bags/puffiness. Also heard models use “Preparation H” for bags, too.

http://women.webmd.com/features/banish-the-bags-under-your-eyes