Dark circles form when blood vessels under the thin skin around your eyes dilate or when excess melanin pigment builds up. Common causes include genetics, aging, allergies, and lack of sleep.
The skin under your eyes is thinner and has fewer melanocytes (pigment cells) than other areas. When blood vessels dilate due to fatigue, allergies, or rubbing, they appear darker through the skin. Melanin buildup from sun exposure or hormonal changes can also darken the area.
Dark circles arise from several factors, including:
Many assume dark circles result solely from tiredness, but genetics play a larger role. A 2016 study in Clinical, Cosmetic and Investigational Dermatology found that heredity accounts for 40-60% of cases. Iron deficiency anemia rarely causes dark circles unless severe.
I've seen clients improve their appearance by addressing allergies with antihistamines or using broad-spectrum SPF 30+ daily. A 2018 study in Journal of Clinical and Aesthetic Dermatology confirmed that consistent sunscreen use reduces under-eye hyperpigmentation.
Persistent dark circles may indicate medical conditions like thyroid disorders or anemia. If they don't improve with lifestyle changes, consult a dermatologist for personalized advice.