“You look really tired, are you okay?” I hate this line of inquiry. You think it’s caring. You think it’s supportive. But really, someone has just looked you straight in the eye, and said “You don’t look too good,” and they have gotten away with it. When you’re feeling more like Sleepy and Dopey, than Snow White, the last thing you want to be told is that you look like it too. What people really should say, is “It seems you have some periorbital hyperpigmentation, are you getting enough sleep?” Then, not only would they sound über smart (because they just used the word peri without discussing Nando’s chicken), they would also get the answer that they wanted, without turning you into another dwarf, Grumpy.

So what is periorbital hyperpigmentation? It’s one reason we get dark circles under our eyes, and if you keep reading, you’ll find out a couple of other reasons too.

 Eyes on the prize

In most people the dark circles under their eyes are blood vessels that we see through the skin. The skin around our eyelids (periorbital skin) is the thinnest skin in the body. It is around 0.5 mm, compared with 2 mm in other areas. As we get older, and our skin loses collagen, it gets thinner, and more translucent. This is why oldies seem to have darker circles around their eyes. Losing fat can also thin the periorbital skin, because your body won’t be storing so much fat around the eyes. Sometimes, the red muscles in our face can also be seen through the thin periorbital skin and this can appear purple (because the red from muscles plus the blue from blood vessels equals purple).

 Why do we have darker circles when we’re tired?

 Scientists aren’t 100 percent sure why being tired brings out the bags, but there are several theories.

 Theory number 1: Blood moving around the body

Blood flows from our face and eyes to our heart through the internal jugular vein (which runs down the inside of the neck). Blood flows more efficiently from the eyes when we are lying down, rather than when we are standing up. Theory number 1 suggests that when we are tired we can see more blood around our eyes, because the blood hasn’t been able to flow away from the area while we were lying down. This also explains why being iron deficient is another reason that we get dark circles under our eyes. Iron is needed to get blood moving efficiently. Less iron, means less blood movement, which in turn means we might be able to see more blood under our eyes (see Popeye: More Spin than Spinach). Plus, iron deficiency leaves us looking paler than usual and pale skin is more translucent, which would mean that more blood vessels would appear.

 Theory number 2: Mast Cells

Another possible reason for why we get dark circles when we are tired (according to my personal hero, Dr. Karl Kruszelnicki), is because there are a lot of mast cells around our eyes. Mast cells are specialized cells that release histamine. Histamine’s main function in the body is to increase swelling, and it does this by expanding our blood vessels. When mast cells release histamine, blood vessels expand leaving more blood behind our eyes, and more visible bags. When we rub our eyes (which we often do when tired) mast cells release more histamine than usual, which means, there will be more blood flow around our eyes, and more visible blood under our thin periorbital skin.

 Theory number 3: Dehydration

When we’re tired, we generally don’t look after ourselves as well as we should. We drink too much coffee, and too little water, so dehydration often comes hand in hand with tiredness. We aren’t precisely sure why dehydration increases the darkness under our eyes, but possibly because dehydration lowers blood pressure, leading to blood moving slower around our eyes.

 Dr. Ellen C. Gendler, a dermatologist from New York suggests, as a short term solution for darkness under your eyes, pressing down on the dark area under our eyes and pulling skin to the side. This forces blood that collected under the eyes to move away from the area, and slightly improves the appearance of bags.

 So, after all this, what’s periorbital hyperpigmentation?

 Melanin is skin pigment; it’s what gives our skin colour, and it’s made by special melanin producing cells (called Melanocytes). Periorbital hyperpigmentation is the official name for when there is more melanin produced around our eyes than usual. The overproduction of melanin gives the skin around the eyes a darker colour.  We have two main layers of skin, the outer layer of skin (epidermis) and inner layer (dermis).When excess melanin is being made in the epidermis it looks brown, but when there is excess melanin in the dermis it looks blue or blue grey. Some people have a surplus of melanocytes around their eyes from birth (it’s just the way their genes made them). Other people might develop hyperpigmentation after inflammation caused by an allergic reaction around their eyes.

 Most likely, you won’t have periorbital hyperpigmentation, you’ll just be tired. So your skin will be paler than usual, and your blood won’t be flowing as well as it usually does. To get back to your normal, happy and bashful self, just lie down for a little (even if you don’t fall asleep, it should still help) and drinks some water. Better yet, until you return to your Snow White complexion, just stop looking in that Mirror Mirror on the wall.

 Ways to reduce dark circles under your eyes?

• Lying down should encourage the blood under your eyes to flow away from his area, reducing the appearance of bags.
• Don’t rub your eyes! Rubbing your eyes will release histamine, which expands blood vessels and let’s more blood to flow under your eyes.
• Drink water, and keep your hydration levels up.