Tired-looking eyes can signal a bad night spent tossing and turning. But puffy eyes and dark circles aren’t always the result of a sleepless night. Redness and irritation can be the product of allergies. Dark circles under the eyes may traced to genetics and the production of too much pigmentation. Staring at a computer screen all day can make your eyes look tired. Struggling to read or squinting to see stop signs can give you eye strain. Keep reading for some causes of tired-looking eyes and solutions that will give you a bright-eyed appearance.

Allergies

Over-the-counter antihistamine meds can treat puffiness and nightly cold compresses can help reduce swelling. Avoid rubbing or scratching your eyes, which only worsens the dark circles and tired look.

The allergy culprit—histamine— is a chemical released by allergies. Histamine cause itchiness that leads to swelling, inflammation and fluid accumulation under the eyes. The chemical also dilates blood vessels, which increases blood flow under the eyes.

Eye strain

Rest your eyes from the computer screen every 20 minutes by looking at an object 20 feet away for 20 seconds. You may need glasses if you’ve been straining your eyes while struggling to read or see far-away signs. Eye strain causes blood vessels around the eye to dilate and increases blood flow. The result is dark circles and tired eyes.

Dehydration

Drink more water. The skin around the eyes is very sensitive to hydration and the environment. Dehydration can lead to exhaustion by decreasing your blood volume and making your heart work less efficiently. Eyes look tired even if you’ve slept a full eight hours.

Excessive under-eye pigment

Wear sunscreen every day for protection against the sun exposure that can exacerbate hyperpigmentation. Look for sunscreens formulated to be gentle on the sensitive eye area, such as SkinCeuticals Physical Eye UV Defense.

Products that contain the brightening agent vitamin C, such as Dr. Andrew Weil for Origins Mega-Bright Dark Circle Minimizer, lighten dark circles caused by excess pigment.

Try this test to see if your circles are caused by darkness from pigment. Press lightly below your eye with a finger. If you see no change when you lift your finger, the cause is excess pigment. If the circle lessens and then becomes dark again, the problem is caused by blood vessels.

Bone structure

The contour of your skull may include a tear trough—a groove running from the inner corner of the eye out along the cheek—that is deep enough to create a noticeable semicircle under the eye. Sunken eye sockets create shadows that make dark circles more noticeable.

Prominent veins

Skin around the eyes is extremely thin and transparent and allows blue-black blood in the veins to show through easily. Lying down at night allows blood to pool in vein under the eyes and makes blue circles most noticeable in the morning.

Try testing a vitamin K-based cream such as the Glycolic Treatment Eye Cream, $105, from Cane and Austin by applying twice a day for two weeks to see if vascular dark circles are reduced. The vitamin K doesn’t work for everyone. If the test doesn’t show improvement, you may want to consult a cosmetic physician.

Read More: Reasons Your Eyes Look Tired That Have Nothing to Do With Sleep—and What You Can Do