Dark circles under the eyes are one of the most common cosmetic concerns, and they rarely point to a single cause. The skin beneath your eyes is the thinnest on your entire face, measuring roughly 0.5 to 0.6 millimeters thick compared to nearly 2 millimeters on the nose. That extreme thinness makes blood vessels, pigment changes, and volume loss far more visible here than anywhere else. Understanding which type of dark circle you’re dealing with is the first step toward addressing it.
Four Types of Dark Circles
Dermatologists generally classify dark under-eye circles into four categories: pigmented, vascular, structural, and mixed. Pigmented dark circles come from excess melanin in the skin itself. Vascular dark circles are caused by blood vessels showing through thin skin or becoming congested. Structural dark circles result from shadows cast by hollows, puffiness, or fat loss beneath the eye. Most people have a mixed type, with two or more of these factors contributing at once.
Knowing your type matters because the fixes are different. A shadow from volume loss won’t respond to a brightening cream, and excess pigment won’t improve with better sleep alone.
Genetics Is the Leading Cause
Heredity is the single biggest factor behind dark under-eye circles. If your parents or siblings have darker skin beneath their eyes, you are significantly more likely to develop it too. What’s inherited can vary: some people are born with naturally thinner periorbital skin, others with more melanin production in that area, and others with deeper-set bone structure that casts shadows.
People with darker skin tones tend to have more melanin activity around the eyes, making pigmented dark circles especially common in South Asian, Southeast Asian, Middle Eastern, and African populations. This isn’t a flaw or a health problem. It’s simply how pigment is distributed in the skin.
How Aging Creates Hollows and Shadows
As you age, the fat pads beneath your eyes shrink and shift downward. At the same time, the ligaments that hold those fat pads in place weaken and stretch. The result is a deepening groove between the lower eyelid and the cheek, known as a tear trough. This groove creates a shadow that looks like a dark circle even when the skin itself isn’t discolored at all.
The central portion of the ligament beneath the eye is the weakest and stretches the most over time, which is why the hollowing often appears most pronounced directly below the inner corner of the eye. Meanwhile, the eyeball itself settles slightly lower in the socket with age, and fat can push forward against the lower lid, creating puffiness above the hollow. That combination of a puffy lid sitting above a sunken groove amplifies the shadow effect considerably.
Bone loss in the upper jaw also plays a role. As the maxillary bone slowly resorbs over decades, the structural support beneath the eye diminishes, making the tear trough deeper and more visible.
Blood Vessels Showing Through Thin Skin
The vascular type of dark circles happens when the network of tiny blood vessels beneath the eye becomes visible through that ultra-thin skin. These circles often have a blue, purple, or reddish tone rather than a brown one. They tend to be more noticeable in people with fair or translucent skin, and they can worsen when blood flow to the area slows down.
Anything that dilates blood vessels or increases fluid retention around the eyes can make vascular dark circles more prominent. Poor sleep is a classic trigger: when you’re sleep-deprived, blood vessels dilate and fluid pools in the under-eye area. Alcohol, high-sodium meals, and even sleeping face-down can produce the same effect by morning.
Allergies and Sinus Congestion
If your dark circles seem to worsen during allergy season, there’s a direct physiological explanation. When your immune system reacts to allergens, the lining inside your nose swells. That swelling slows blood flow through the veins around your sinuses, and those veins run very close to the surface of the skin beneath your eyes. As blood backs up and the veins swell, the area looks darker and puffier. Doctors sometimes call these “allergic shiners.”
This isn’t limited to seasonal allergies. Chronic sinus congestion, dust mite sensitivity, pet allergies, and even frequent colds can produce the same venous congestion. Rubbing itchy eyes compounds the problem by triggering post-inflammatory pigmentation, where repeated friction causes the skin to darken over time.
Sun Exposure and Skin Damage
Ultraviolet light accelerates nearly every process that worsens dark circles. UV rays stimulate melanin production, making pigmented dark circles darker. They also generate reactive oxygen species, unstable molecules that damage collagen, cell membranes, and DNA in the skin. Over time, this breaks down the already thin under-eye skin further, making blood vessels more visible.
The periorbital area is particularly vulnerable to UV because the skin there is so thin to begin with. Sunglasses with large lenses offer meaningful protection. Smaller lenses increase the probability of UV radiation reaching the skin around the eyes, so oversized frames aren’t just a fashion choice.
Iron Deficiency and Other Health Factors
Low iron levels can make dark circles worse by reducing the oxygen-carrying capacity of your blood. When hemoglobin drops, the skin looks paler overall, which increases the contrast between the under-eye area and the rest of the face. In clinical cases, periorbital pigmentation has been documented alongside significant anemia, where hemoglobin levels dropped well below the normal range.
Dehydration can produce a similar effect. When your body is low on fluids, the skin loses volume and the eyes appear more sunken, deepening shadows. Thyroid disorders, eczema (particularly atopic dermatitis around the eyes), and certain medications can also contribute, though these are less common causes than genetics, aging, or lifestyle factors.
Sleep, Stress, and Screen Time
Sleep deprivation doesn’t cause dark circles from scratch, but it reliably makes existing ones worse. During poor sleep, cortisol levels rise and blood vessels dilate. Fluid that would normally drain away from the face during upright hours accumulates around the eyes. The result is a combination of puffiness and visible vessels that creates that exhausted look.
Chronic stress operates through a similar mechanism, keeping cortisol elevated and impairing skin repair. Extended screen time contributes by straining the muscles around the eyes and reducing blink rate, which can increase eye fatigue and the appearance of darkness. None of these factors work alone, but stacked together, they can turn mild genetic dark circles into much more noticeable ones.
Why They Look Worse on Some Days
Dark circles fluctuate because several of their causes are variable. A salty dinner causes fluid retention overnight. A night of broken sleep dilates blood vessels. Seasonal allergies trigger nasal congestion for weeks at a time. Crying produces both swelling and redness. Even your menstrual cycle can affect fluid distribution and skin appearance.
The structural component, the hollows from fat loss and bone changes, is the one factor that stays constant and gradually worsens with age. Everything else layers on top of it. This is why your dark circles can look dramatically different from one morning to the next, and why addressing the modifiable triggers (sleep, hydration, allergen exposure, sun protection) can make a noticeable difference even when the underlying anatomy can’t be changed with skincare alone.