What causes dark circles under the eyes?

I love sleep; it’s my favorite – Kanye West

What are dark circles?

When was the last time you really looked at your eyes?  If you take a really close look you may find that the coloring of your skin under your eye is slightly darker than the rest of your eye and face.  This condition is called dark circles, also known as periorbital hyperpigmentation (POH), periocular hyperpigmentation, periorbital melanosis, infraorbital darkening, infraorbital discoloration, or idiopathic cutaneous hyperchromia of the orbital region.  It is especially prominent in women of color (like myself) and may also be a genetic present from our ancestors for some of us  :|).

Nobody can argue that Kim Kardashian isn’t beautiful.  I came across the pic that shows Kim with and without makeup to highlight how dark circles can impact how we look.

(Source:  https://www.health.com/beauty/kim-kardashian-dark-circles-concealer-routine)

Throughout cultures, societal perceptions are similar, in that dark circles contribute to a tired, aged and even sad appearance. On average, a woman in the United States spends $15,000 (USD) in her lifetime on cosmeceuticals and makeup, a large percentage of which is spent on under-eye concealers.

Now Kim has beautiful skin but she like many of us experience dark circles under our eyes from time to time.  There are really amazing things we can do with makeup to conceal the look of dark circles, but in this article I’m focused on understanding why they exist in the first place.

What causes dark circles?

1. Thin skin around the eyes.  We know from our skin basics review that the skin around our eyes is much thinner than the skin on the rest of our body.  As a result, the skin around our eyes is more transparent to the underlying blood vessels than in other parts of our body.  As we age and this skin thins even more, the exposure to the underlying blood vessels increases.  In addition, the dermis, epidermis, and subcutaneous layers lose their volume over time which creates additional transparency on the surface to underlying blood vessels.
2. Poor microcirculation.  Dark circles start with leakage of red blood cells (hemoglobin) from the small capillaries in the eye area due to increased permeability of blood vessels and capillaries as we age. When hemoglobins escape from small capillaries, they explode in the dermis and epidermis layers of the skin.  In this process,  hemoglobin is divided into its two main components, the heme group and the iron. The degradation of the heme group results in biliverdin (dark green-violet pigment) and bilirubin and iron that give rise to a dark brown to orange-red pigment. The consequence is an accumulation of iron and poorly soluble pigments which creates the dark-bluish color of dark circles.
3. Melanin accumulation.  Melanin is the primary pigment that determines the color of our skin.  This pigmentation varies across the world and has evolved mostly to regulate the penetration of UV levels, i.e. cultures closer to the equator have darker skin as they have the highest exposure to UV of all cultures.  If a condition is created that causes excessive production of melanin, i.e. overexposure to sun, it can give the appearance of dark circles under your eyes.
4. Genetics.  One of the primary contributors to dark circles is genetics with patients of darker skin types, such as those of Mediterranean descent, being being more prone to this condition because they have more pigment, or melanin, in their skin.  Some of us are born with depressed tear troughs or thinner skin around the eye which only worsens as we age.
5. Sleep.  Lack of sleep can make your skin appear pale which increases the visibility of blood vessels underneath.  Further, skin deprivation can cause the blood vessels under the thin skin of the eyes to dilate which creates a dark tint and puffiness under the eye.
6. Sleep position.  Sleeping in certain positions, such as on your stomach or not sleeping in an elevated position, can worsen dark circles because gravity causes blood to pool under the eye.
7. Free radicals.  A free radical is defined as a molecular species capable of independent existence. Free radicals are unstable (meaning they do not have the full complement of electrons in their outer shell) and are considered reactive in that in an effort to make up the number of electrons in their outer shell, they react quickly with other substances.  Antioxidants exist to destroy free radicals . When oxygen molecules split into single atoms that have unpaired electrons, they become unstable free radicals that seek other atoms or molecules to bond to. If this continues to happen, it begins a process called oxidative stress.  Oxidative stress can cause collagen and elastin fibers to break down and stimulate excessive production of melanin, both of which can increase the appearance of dark circles under the eye.
8. Dehydration.  Not drinking enough water causes the skin to lose elasticity and dry out, and underneath the eyes, the skin can also start to look transparent, giving it a darkened look.
9. Anemia.  Iron is very important in maintaining many body functions, including the production of hemoglobin, the molecule in your blood that carries oxygen.  Symptoms of iron-deficiency anemia are related to decreased oxygen delivery to the entire body which includes pale or sallow skin.  This paleness in your skin color under your eye magnifies the presence of underlying blood vessels, making them appear more darker and creating the look of dark circles under the eye.
10. Allergies.  Histamine is produced by cells in the body when it is undergoing an allergic reaction.  If the immune system detects something harmful, histamine increases blood flow to the affected area, dilating blood cells.  If an allergy causes congestion in your sinuses, this can lead to congestion in the small veins under your eyes. The blood pools under your eyes and these swollen veins dilate and darken, creating dark circles and puffiness.  Allergies can also cause eyes to itch.  When we rub our eyes, this friction irritates and breaks the small blood vessels under the skin, which can cause redness, swelling and discoloration.  Additionally, allergies result in inflammation that expands the capillaries under the eyes, causing them to appear more easily than when they are in a constricted state.
11. Smoking.  Smoking pollutes skin cells and prevents oxygenation of cells. It dilates and kills and/or damages blood cells. This process causes dark circles, wrinkles, and dehydration.
12. Medications.  Any medications that cause blood vessels to dilate, e.g. hypertension medications, can cause circles under the eyes to darken.
13. Diet.  Dark circles under the eyes can be a sign of a vitamin K or C deficiency, excessive consumption of alcoholic drinks and caffeinated drinks, too much salt, not enough water (as discussed in reason #7 above), or potential allergies to foods.  Without sufficient vitamin K the blood will not clot properly, and any leakage from the tiny capillaries under the eyes may pool and create very dark, bruise-like discoloration.  Vitamin C is known to strengthen the walls of blood vessels, preventing them from leaking. Both alcoholic drinks and caffeinated drinks like soda, coffee, and tea can increase dehydration.  While salt itself may not directly cause dark circles, excessive salt intake can increase the fluid in your body which causes puffiness under the eye that exacerbates the appearance of dark circles.

Sources

1. Dermatological Surgery, 2009; 35:1163-1171
2. Journal of Cosmetic Dermatology, 2007; 6:211-215
3. Journal of Cosmetic Dermatology, 2004 ; 3(2):73-5
4. How to treat the eye contour, http://institutebcn.com/en/how-to-treat-the-eye-contour/
5. A.G.E. Eye Complex, http://www.drsearles.ca/a-g-e-eye-complex-skinceuticals
6. Sarkar, R., Ranjan, R., Garg, S., Garg, V. K., Sonthalia, S., & Bansal, S. (2016). Periorbital Hyperpigmentation: A Comprehensive Review. The Journal of Clinical and Aesthetic Dermatology, 9(1), 49–55.
7. 2. Mint.com. Ross Crooks. Splurge vs Save: Which Beauty Products are Worth the Extra Cost? [Last cited on 2016 Jan 05]. Available from: https://www.blog.mint.com/consumer-iq/splurge-vs-save-which-beauty-products-are-worth-theextra-cost-0413/?display=wide .
8. What Causes Dark Circles Under Your Eyes?, https://www.healthline.com/health/dark-circle-under-eyes
9. Freitag FM, Cestari TF. What causes dark circles under the eyes? J Cosmet Dermatol. 2007;6:211–5.[PubMed]
10. Amani Saad (2017) News in the Treatment of Periorbital Hyperpigmentation. J Dermatol & Ther 1:106. [http://hendun.org/journals/JDT/PDF/JDT-17-1-106.pdf]
11. Sami Rahman, How to tackle dark under eye circles in ethnic skin, (2014) [http://www.netdoctor. co.uk/beauty/a8995/how-to-tackle-dark-under-eye-circles-in-ethnic-skin]
12. Mitzuguchi, R. MD.  How do I get rid of dark circles?, Mount Sinai Research Institute (November 2012), http://inside.mountsinai.org/blog/how-do-i-get-rid-of-dark-circles-under-my-eyes/
13. Phillips DJ, Schei JL, Rector DM. Vascular compliance limits during sleep deprivation and recovery sleep. Sleep. 2013;36:1459–1470. [PMC free article] [PubMed]
14. Zielinski, M. R., McKenna, J. T., & McCarley, R. W. (2016). Functions and Mechanisms of Sleep. AIMS Neuroscience, 3(1), 67–104. http://doi.org/10.3934/Neuroscience.2016.1.67
15. Miller, C. The Real Causes of Your Under Eye Circles. (2015). http://stylecaster.com/beauty/what-causes-under-eye-circles/
16. Iron Deficiency Anemia.  http://www.hematology.org/Patients/Anemia/Iron-Deficiency.aspx, American Society of Hemotology
17. “Dark Circles Under the Eyes”. Medicine.net. Medicine.net. 2012-06-03. Retrieved 2016-04-27.
18. Dovey, C.  Headaches? Eczema? Tummy pain? They could all be caused by a common food allergy your doctor’s never heard of.  https://www.dailymail.co.uk/health/article-1373395/Histamine-intolerance-Common-allergy-causes-bloating-eczema.html
19. What Are Allergic Shiners?, https://www.healthline.com/health/allergic-shiners#treatments-and-homeremedies
20. Baum, I.  7 Surprising Reasons You Have Dark Circles Under Your Eyes (2018) https://www.msn.com/en-us/health/wellness/7-surprising-reasons-you-have-dark-circles-under-your-eyes/ss-AAukE8a#image=3
21. How Free Radical Damage Causes Dark Circles, https://www.consumerhealthdigest.com/eye-skin-care/dark-circles-causes.html
22. Villines, Z.  How do free radicals affect the body? (July 2017) https://www.medicalnewstoday.com/articles/318652.php