We've all had that oh my god moment: looking in the mirror one morning and seeing dark circles or unsightly puffy eyes. Maybe it's an every day occurrence for you (this particular editor was blessed with -- luckily, fairly mild -- genetic dark circles), but if not, there's a couple things that can be causing it, things you may be doing that are totally fixable.

First, it's important to understand that the skin around your eyes is the thinnest skin on your entire body, and as such is the most sensitive to change. From the flow of fluids to the tugging of regular makeup application, it's susceptible to a lot more damage than the rest of your body. The two major problems we see with our eyes (other than wrinkles) are puffiness and dark circles. Here's why.

Puffy Eyes
Puffiness comes from a range of causes: from a cold or sinus infection and seasonal allergies, to eating a salty dinner or watching a tear-jerker before bed. In truth, it's all about osmosis: water will move from areas with a low concentration of salt to areas with a high concentration -- in an effort to balance out the levels of sodium. So whether you were crying a lot watching "The Notebook" last night or ate an entire bag of salty pretzels, your body is going to over-compensate.

Another cause of puffy eyes could come from the way you sleep. Sleeping on your side or your stomach may cause fluids to pool in your eyes (if this is the case, sleeping on your right will result in more puffiness in that eye). It's not easy to change, but if this is your problem, try sleeping on your back!

Some more causes of puffiness are rubbing your eyes a lot or falling asleep with makeup on. Not only are these proponents of wrinkles and breakouts, respectively, but they risk irritating your eyes too. Cutting down on these behaviors will reduce this unsightly issue. If you have fluid retention thanks to a salty meal, try snacking on bananas or raisins, which will alleviate the problem. If tears are your issue, try applying a cool compress under your eyes, or cooled-down tea bags.

Dark Circles
Dark circles are often associated with tiredness, but they can be caused by a lot more than a lack of sleep. Unfortunately, some of us are born with them! Genetics always play a role, and pigmentary issues that cause under-eye discoloration is common among people of Asian and African descent. The other unavoidable cause of dark circles is simply age -- our skin things as we age, and as this particular skin is already thin, this effect will increase the visibility of the tiny blood vessels in the area. With age, while you lose volume in the area under your eyes, it also exposes the orbital bone -- creating a hollow "trough" that looks like a dark circle.

So ask yourself this question: do you have blue under-eye circles, or brown? Brown circles are often the first of the two causes: genetics. But it can also be because of hyperpigmentation caused by rubbing your eyes a lot or excessive exposure to the sun. Try using a cream containing soy or citrus that will gradually brighten the skin over six weeks, and do your best to stop rubbing your eyes. As always, sunscreen is key for your safety -- and for maintaining glowing skin!

If your circles are blueish, it's because of pooling blood in the area under your eyes, and will likely be most visible in the mornings. When you're sleeping, fluids will accumulate and your veins will expand to hold more blood. A lack of sleep often gives you dark circles, because you'll look paler and thus more hollow-eyed. Aging is often a factor in this type of dark circle, because as mentioned above, thinning skin will expose the blood vessels more.

There are a couple quick fixes for dark circles, the most immediate weapon in your arsenal being makeup. Choose a concealer that matches your skin tone (you may have been told to go a few shades lighter, but this is never a good look!). If you have mild circles go for a liquid formula, darker discoloration will need a heavier cream or cake concealer. If your skin is thin, you can try using creams with caffeine in them, which will constrict the blood vessels and temporary boost circulation. You can fight the good fight on a daily basis by applying night cream. Products with hyaluronic acid will plump the area, hydrating the skin and pushing it up and away from the blood, whereas those containing retinoic acid will thicken the skin to conceal the darkness. As always, when applying concealer or cream to your eyes, PAT, do not drag, the product from the corner of your eyes to just past the edge.

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