AFF | Awesome Fun Facts

It is often claimed that periorbital dark circles are caused by tiredness or working too hard or even just staying up late. While this can be true, the truth is that your genes play a huge role here. So what exactly is happening when you get dark circles under or around your eyes?
Simply put, periorbital dark circles are a result of the thin layer of skin below your eyes showing the blood vessels and the blood they contain more clearly than anywhere else on your body. (For reference, this skin around your eyelids, called periorbital skin, is on average about 0.5 mm thick compared to an average of about 2 mm thick on most of the rest of your body.)
Now, as you may or may not already know, the reason veins often look blue isn’t because the blood inside them is blue; it’s because your skin/subcutaneous tissue only lets blue/violet wavelengths of light pass through it. As a result, only blue light is reflected back and the veins look, well, bluish. (Veins often won’t appear blue if a person has darker or lighter skin. Rather, the veins tend to appear green or brown. On the other hand, people with extremely light skin, such as albinos, will typically have veins that show up as dark purple or dark red, more closely resembling the actual color of the blood running through the veins.)
It’s the exact same concept with the skin below your eyes. Those dark bluish circles are (usually) just the result of light being reflected back off of the blood vessels sitting just below the surface of that incredibly thin patch of skin. This is the same reason facial bruises are more prominent below or around the eyes; the thin skin just shows the blood from the ruptured blood vessels a little bit more clearly.
Again, as you may or may not know, as we age, our skin loses its elasticity and ability to regenerate and as a result, it becomes thinner. This is why more often than not, elderly people will have rather prominent periorbital dark circles regardless of how much they sleep. As with those who are genetically predisposed to having thinner skin below the eyes, it’s just biology.
Another thing that can cause dark circles beneath the eyes is something known as periorbital hyperpigmentation, which is basically a condition that results in more melanin being produced by the skin below the eyes, resulting in it appearing to be a darker color. This is mostly a condition that affects (or is at least more noticeable in) darker skinned people. According to Pratik B Sheth et al. of the PDU Government Medical College and Hospital in India, this is one of the most common complaints dermatologists have to deal with. Unfortunately, as explained in this case study about an Indian gentleman with a particularly severe case of periorbital melanosis, it’s very difficult to treat in darker skinned patients, which has led to a booming niche market of cover up make-up for people with darker complexions.
All that said, there are a number of factors that can make dark circles appear worse, even if you’re not genetically predisposed to them. One of the more serious sounding is the oxidisation of blood leaking from the periorbital blood vessels, which is just a fancier way of saying that sometimes the blood vessels around your eyes can get damaged, blood leaks out, and you’re left with puffy dark circles under your eyes. It’s a relatively harmless problem and even the chronic sufferers of this sort of blood leaking need not worry too much about it. It is also technically reversible with the right treatment, though changes in lifestyle are often recommended before one should consider opting for surgery.
Another problem that goes hand-in-hand with periorbital dark circles is periorbital puffiness, aka bags below your eyes. In young folk, this is almost always caused by fluid buildup below the eyes, either due to illness, allergies or simply excessive salt consumption which can result in the body retaining more fluid than usual. This can place increased pressure on the skin and blood vessels around the eyes which can force blood vessels closer to the surface of the skin, making dark circles appear more prominent. Eye puffiness can also simply be a result of old age.
Now all of that is (hopefully) interesting to you, but we still haven’t specifically answered the question: Can those dark circles be caused by fatigue and, if so, why? Well the answer to the former is: sometimes. So why exactly is this the case? It’s not like lack of sleep makes your skin thinner, right?
Well the answer is thought to lie in how the body acts when it’s low on energy. When the body is tired, production of the chemical cortisol is dramatically increased to help give you the energy you need to stay awake. Among many other things, cortisol actually increases the volume of the blood in your body, which causes the blood vessels (including the ones below your eyes) to engorge to accommodate it. As we’ve already mentioned, dark circles are mostly caused by us seeing our blood vessels / blood through our skin, so it stands to reason that when those blood vessels are engorged, they’d be easier to see, even in people who may have been blessed with thicker skin below their eyes.
So, whether by passing on their genes to you or for not letting you sleep in after a gaming all-nighter when you’re young, it’s all your parent’s fault. Something that is/was even more reckless of them as cortisol promotes fat accumulation. So your lack of sleep is likely contributing to more than just under-eye cosmetic issues.