Dark circles under your eyes. Your genes may be the real culprit.

Filaggrin (FLG) is the structural protein that forms your skin barrier. Think of it as the mortar between bricks. When filaggrin is present and working properly, your skin cells are tightly bound together, moisture is locked in, and irritants can’t get through. This is critical for the thin, delicate skin around your eyes, which has fewer oil glands and less natural protection than the rest of your face.

If you carry loss-of-function FLG variants like R501X or 2282del4, roughly 10% of people with European ancestry do, your skin barrier is fundamentally compromised. Your skin cannot retain moisture effectively, and irritants penetrate deeper than they should. This makes the eye area chronically inflamed and reactive. The inflammation triggers melanin production as a protective response, creating dark circles that get worse with stress, weather changes, or any irritant exposure.

You’ve probably noticed that your dark circles flare after certain products, after traveling, or after high-stress periods. The skin feels tight and dry, then darkens. You might also get eczema or dermatitis around the eyes. This isn’t random; it’s your broken barrier responding to a threat the way a barrier would.

The vitamin D receptor (VDR) is the master switch that allows vitamin D to regulate your immune system, control skin cell growth, and calm inflammation. When VDR is working optimally, vitamin D signals your immune cells to cool down and tells skin cells to renew properly. Your skin stays calm, well-regulated, and doesn’t overreact to minor irritants.

If you carry VDR variants like BsmI or FokI, which roughly 30-50% of the population carries, your cells don’t respond to vitamin D as effectively. Even if your blood vitamin D levels look normal, your skin cells aren’t receiving the anti-inflammatory signal they need. The result is a skin barrier that’s hyperreactive, immune signaling that stays elevated, and melanin production that doesn’t turn off when it should. The delicate eye area, which is exquisitely sensitive to immune signals, darkens as a result.

You might notice that your dark circles improve slightly in summer when you get more sun exposure and vitamin D production is high, then return in winter. This seasonal pattern is a classic VDR signature. You might also have other signs of dysregulated immunity: frequent colds, slow wound healing, or sensitivity to supplements.

MTHFR (methylenetetrahydrofolate reductase) is the enzyme that converts dietary folate into methylfolate, the activated form your cells actually use. Methylfolate is essential for DNA synthesis, cell division, and the rapid regeneration of skin cells. Your skin cells turn over every 28 days; if you don’t have enough active folate, that turnover slows, and dead cells accumulate. This is especially noticeable in thin areas like the eye region, where cell turnover is everything.

If you carry the MTHFR C677T variant, which roughly 40% of people with European ancestry carry, your enzyme works at 40-70% efficiency. You can eat all the leafy greens you want, but your cells can only convert a fraction of it into usable methylfolate. This means your skin cells regenerate slowly, inflammation persists longer, and the delicate eye area ages faster. Melanin-producing cells also regenerate slowly, which can paradoxically lead to uneven pigmentation and dark circles that don’t fade.

You’ve probably noticed that your dark circles are worse when you’re stressed or when you skip green vegetables, and better on periods when you’re eating extremely well. Your skin feels tired and dull. This is the hallmark of impaired methylation: everything works, but slowly.

SOD2 (superoxide dismutase 2) is an antioxidant enzyme that lives inside your mitochondria, the power plants of your cells. Its job is to neutralize free radicals, the unstable molecules that damage DNA, proteins, and fats. Your skin cells generate enormous amounts of free radicals just from normal metabolism, and the sun generates even more. If SOD2 is working well, free radicals are neutralized before they cause damage. If it’s not, damage accumulates.

If you carry the SOD2 Val16Ala variant, roughly 40% of the population carries the homozygous variant, your antioxidant defense is reduced by roughly 20-30%. Free radicals accumulate in your skin cells, particularly in the thin, fragile eye area where there’s less tissue to absorb the damage. This oxidative stress triggers melanin production as a protective response: your skin darkens in an attempt to shield itself from further damage. You get dark circles that look almost like a tan, but localized to the eyes.

You’ve probably noticed that your dark circles are worse after sun exposure, after stress, or when you’re not sleeping well. They’re also worse when you’re exercising hard or eating foods that increase oxidative stress. The darkness has an almost brownish or grayish tone, not the bluish tone of poor circulation.

Tumor necrosis factor-alpha (TNF) is a potent inflammatory cytokine, a signaling molecule that tells your immune system to activate. In the right amount, TNF is protective. But if your genes push you toward higher TNF production, your baseline inflammatory state stays elevated all the time. Inflammation drives melanin production and thickens the blood vessels under your skin, both of which darken the eye area visibly.

If you carry the TNF -308G>A variant, roughly 30% of the population does, your immune cells produce more TNF-alpha than the baseline. This keeps your skin in a state of low-grade chronic inflammation, which accelerates pigmentation in the delicate eye area and makes the skin appear darker and more tired. The inflammation is invisible; your skin doesn’t look red or irritated. But it’s there, signaling melanin-producing cells to work harder and blood vessels to dilate slightly. The result is dark circles that look almost purple or ashy.

You’ve probably noticed that your dark circles are worse during stressful periods, after poor sleep, or when you’re dealing with any kind of infection or illness. They’re also worse if you eat inflammatory foods or skip exercise. The darkness has an ashy, almost bruised quality to it.

Interleukin-6 (IL6) is an inflammatory cytokine that amplifies inflammatory responses. It’s like the volume knob on your immune system. When you have an infection or injury, IL6 goes up to mobilize your immune response. But if your genes push you toward higher IL6 production, even minor triggers cause a disproportionate inflammatory response. This chronic low-grade inflammation shows up first in thin, sensitive skin like the eye area.

If you carry the IL6 -174G>C variant, which roughly 40% of the population carries the C allele, your cells produce more IL6, especially under stress. This means every inflammatory trigger in your life, from stress to poor sleep to a minor infection, creates an amplified immune response that keeps your baseline inflammation elevated. Your skin responds by producing more melanin as protection, and the delicate eye area darkens noticeably. The inflammation is systemic, not localized, so you might notice dark circles get worse alongside brain fog, joint stiffness, or fatigue.

You’ve probably noticed that your dark circles are exquisitely sensitive to stress, sleep deprivation, and illness. After a bad night, they’re dramatically darker. After a stressful week, they look almost bruised. This amplified response to minor triggers is the signature of high IL6.