Bags under the eyes are a common side effect of a lousy night’s sleep, like the body’s way of announcing to the world that "yes, I would rather be in bed right now". As for what causes dark circles under our eyes when we’re tired, it’s a toss-up between your physiology, genes, and behavior. The skin around your eyes is thinner than that on the rest of your face, meaning it’s more prone to losing its structural integrity resulting in laxity, fine lines, and wrinkles. This means that as we age, features that surround the eyes like blood vessels, pigmentation, or sunken under-eyes become easier to spot. What causes dark circles under eyes when we are tired? When we’re overly tired or stressed, our body produces higher amounts of cortisol, a steroid hormone that’s squirted out by endocrine glands on top of our kidneys. Cortisol often gets a bad rap due to its association with depression and weight control difficulties, but releasing it is our body’s attempt to keep us awake and alert. However, high cortisol can also increase the appearance of eye bags as it increases our blood volume by pumping in extra proteins and plasma through osmosis. This uptick in blood volume means our vessels become engorged, including those that sit beneath the eyes. Blood shows up differently depending on the color of a person’s skin. Pale skin often shows blue or green veins as a result of the wavelengths of light reflected from our blood showing up differently. Veins can be quite visible, but get harder to spot with darker skin tones, so the way their color and size change when we're tired can vary. A pale person might have eye bags with coloration that contrasts against their skin, while a darker-skinned person might notice puffiness as the blood vessels fill up. The overall effect is a darkening and puffiness that feels like little billboards advertising our fatigue. Genetic causes of dark circles under eyes While tiredness can trigger eye bags, some people have dark circles under their eyes all the time – and genetics can be the biggest culprit here. If you have naturally thin and pale skin, the blood vessels beneath your eyes will be more noticeable even when your cortisol levels are normal. Periorbital hyperpigmentation is the name given to dark circles around the eyes caused by pigmentation that persists regardless of how awake or tired a person is. The condition is more common among certain ethnic groups and families as it’s caused by a combination of genetic and lifestyle triggers. Lifestyle causes of dark circles under eyes The way you live can also determine your likelihood of developing dark circles under your eyes. As we’ve already explored, tiredness can be a trigger, but so too can overindulging in alcohol, salt, and cigarettes, as these can all make the blood vessels dilate in the same way high cortisol levels do. Research has also found an association between frequent cosmetic use and eye rubbing with periorbital hyperpigmentation. This is likely due to physical interference causing the skin further wear and tear in a way that mimics the effects of aging. Age-related causes of dark circles under eyes The skin around our eyes is thin, just 0.5 millimeters (0.01 inches) thick, whereas the rest of our skin is around 2 millimeters (0.07 inches) thick. However, as we age it loses fat, making it even thinner and more transparent. This means that the natural coloration of healthy vessels under the eyes may appear darker over time simply because the layer that covers them is becoming less opaque. Losing fat here also means that the under-eye area can become hollower. The tear trough – a section of the face so named by dermatologists for its role as a route for fallen tears – is one place where this can happen. The thinner skin can then sag more into these hollow areas, creating a shadowing effect as light reflects off our faces that make eye bags appear more noticeable. The takeaway There are many triggers for eye bags and, despite what magazines may have led you to believe, almost everyone has them. Dark circles under the eye might make you feel self-conscious, but they are often simply a perfectly natural feature of the face. While sleeping enough might help reduce their appearance, perhaps we should learn to embrace the eye bag and just enjoy having a snooze for the sake of snoozing. Source
