* Thinning skin
The skin under the eyes is thin and delicate to begin with. As we age, skin and the fat pad under the eyes becomes thinner, causing blood vessels to become noticeable. This gives the appearance of dark circles. Sun damage can make it worse because it weakens skin.
* Allergies and Hayfever
Dark circles under the eyes can be the result of allergies to airborne substances, such as pollen, dust, and pet dander, because people rub their itchy eyes. People with hayfever may notice them at the height of the season. Food allergies or sensitivities can also contribute to dark circles.
Dark circles under the eyes runs in families. They tend to be more noticeable in people with fair skin or deep-set eyes.
* Fluid Retention
Blood vessels under the eyes can become dilated and engorged, which can contribute to dark circles. Excess dietary salt and smoking are common causes. Conditions that cause fluid retention (e.g. heart, thyroid, kidney, liver diseases) or medications that cause blood vessel dilation may be a factor. Your doctor should be aware of any symptoms you're experiencing.
* Lack of sleep
A lack of sleep can make skin appear more pale, which allows blood vessels to be more visible through the skin, giving the appearance of bluish or dark circles.
* Iron Deficiency Anemia
Iron deficiency anemia may cause a bluish tinge below the eyes.
Dark circles under the eyes can be a sign of dehydration.
Remedies for Dark Circles Under the Eyes
There are some home remedies that may help to temporarily diminish the appearance of dark circles under the eyes, and prevent dark circles from worsening.
1. Be sure to drink enough water. Hydration Calculator: How much water do you need?
2. Wear sunscreen with a minimum of SPF 30 under the eyes to prevent skin weakening caused by sun damage.
3. Get plenty of rest.
4. Apply plain cool teabags over closed eyes. Don’t use herbal teabags, because most aren't as effective.
5. Apply cool cucumber slices over closed eyes for 15 minutes.
6. Be careful not to consume too much dietary salt. Start by learning about sources of sodium in the diet.
7. Apply vitamin K cream. Although studies haven't looked at the use of topical vitamin K for dark circles under the eyes, preliminary studies have found that vitamin K may help with bruising.
8. Vitamin C helps to strengthen blood vessel walls. Quiz: Are you getting enough vitamin C?
9. The dietary supplements grape seed extract and pycnogenol contain antioxidant pigments that may help to strengthen blood vessels. They should be used under medical supervision by people on "blood-thinning" drugs such as Coumadin (warfarin) and aspirin.
Certain foods, such as cranberries, blueberries, bilberries, tea (green and black), black currant, onions, legumes, and parsley also contain these antioxidant pigments.
10. Eat kidney-balancing foods. In Traditional Chinese Medicine, a bluish cast under the eyes are due to an imbalance in kidney energy. Learn more about kidney yang deficiency and foods to eat.
Source: about.com by cathy wong