What causes dark circles?
There are a number of possible reasons for dark circles under your eyes. Some common causes include:

Fatigue
Oversleeping, extreme fatigue, or just staying up a few hours past your typical bedtime can cause dark circles to form under your eyes. Sleep deprivation can cause your skin to become dull and paler. The dark tissues and blood vessels beneath your skin can start to show.

Lack of sleep may also cause fluid to build underneath your eyes, causing them to appear puffy. The dark circles you see may actually be shadows cast by puffy eyelids.

Age
Natural aging is another common reason for dark circles beneath your eyes.

As you get older, your skin becomes thinner. There may be a decrease in the fat and collagen that maintains your skin’s elasticity. As this occurs, the dark blood vessels beneath your skin become more visible, causing the area below your eyes to darken.

Eyestrain
Staring at your television or computer screen may cause strain on your eyes. This strain can enlarge the blood vessels around your eyes. As a result, the skin surrounding your eyes can darken.

Allergies
Allergic reactions and eye dryness can trigger dark circles. When you have an allergic reaction, your body releases histamines to fight off the invader. This causes several symptoms, including itchiness, redness, and puffy eyes. Histamines also cause your blood vessels to dilate and become more visible beneath your skin.

Allergies can increase your urge to rub and scratch the itchy skin around your eyes. These actions can worsen your symptoms, causing inflammation, swelling, and broken blood vessels. This can result in dark shadows beneath your eyes.

Dehydration
Dehydration is a common cause of dark circles under your eyes. When your body is not well hydrated, the skin beneath your eyes begins to look dull and your eyes look sunken. This is due to the eyes’ close proximity to the underlying bone.

Sun overexposure
Sun exposure can cause your body to produce an excess of melanin, the pigment that gives your skin color. Too much sun — particularly for your eyes — can cause pigmentation in the surrounding skin to darken.

Genetics
Family history also plays a part in developing dark circles under your eyes. It can be an inherited trait seen early in childhood. Over time, the dark circles may lighten or get darker.

Predispositions to other medical conditions — such as thyroid disease — can also result in dark circles beneath your eyes.

Anemia
Anemia is when your levels of red blood cells are lower than normal. This can leave you feeling:

dizzy
weak
lightheaded
short of breath
tired
If you have anemia, you may also notice that your skin is paler than usual, and you may have dark circles under your eyes. Talk with a doctor about getting blood work done to check your iron levels. Treatments for anemia include:

dietary changes
iron supplements
iron infusions, depending on your levels
Treatment
At-home treatments
Treatment for dark eye circles depends on the underlying cause. However, there are some home remedies that may help.

Here are some common methods:

Apply a cold compress. A cold compress may reduce swelling and shrink dilated blood vessels to lessen the appearance of puffiness and dark circles. Wrap a few ice cubes in a clean washcloth and apply it to your eyes. You can also dampen a washcloth with cold water and apply it to the skin under your eyes for 20 minutes for the same effect.
Get extra sleep. Catching up on sleep may also help reduce the appearance of dark circles. Sleep deprivation may cause your skin to appear pale, making the dark circles more obvious.
Elevate your head. While sleep deprivation might play a part in producing those dark bags under your eyes, sometimes it’s from how you sleep. Try elevating your head with a few pillows. This may prevent fluid from pooling under your eyes, which makes them look puffy and swollen.
Stay hydrated. Do your best to drink more water. Other fluids can also help keep you hydrated, including milk, tea, and juices. Eating fruits and vegetables also adds to your overall fluid intake.
Soak with tea bags. Tea contains caffeine and antioxidants that can help stimulate blood circulation, shrink blood vessels, and reduce liquid buildup under your skin. Soak two black or green tea bags in hot water for 5 minutes, then chill them in the refrigerator for 15 to 20 minutes. Once they’re cold, apply the tea bags to your closed eyes for 10 to 20 minutes, then remove them and rinse your eyes with cool water.
Try our eye creams. They will reduce the look of dark circles by hydrating and smoothing the skin around your eyes.
Conceal with makeup. If you want to hide dark circles, concealers can cover them so they blend in with your typical skin color. As with any topical treatment or makeup, there is a chance of irritation or an allergic reaction. If you notice any side effects, stop using it and consider talking with a doctor.