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Stress and a lack of sleep can cause a lack of melanin, causing that haggard, jaundiced look.

It’s almost midnight and you’re stuck in a tangle of wrapping paper and ribbon while cookies burn in the oven. You're exhausted but your holiday to-do list keeps you up and working.

After a few hours of fitful sleep, you stumble into the bathroom and gaze in the mirror. Your skin is sallow and the bags under your eyes make you look as if you went five rounds with a prizefighter.

What is it about lack of sleep and stress that makes us look so ragged?

“Stress causes a drop in the skin’s ability to protect itself,” explains Dr. Amit Sood, associate professor of medicine and chair of the Mind Body Initiative at Mayo Clinic. “All of this happens with chronic stress -- if you do not have healthy collagen in your skin, you would have baggy sort of skin under your eyes.”

And stress can also lead to less melanin, causing that jaundiced, haggard look. Melanin pigments the skin, giving humans their complexion.

According to Sood, author of Train Your Brain, Engage Your Heart, Transform Your Life: A Course in Attention and Interpretation Therapy, we're at war with ourselves whenever we're stressed.

“You lose efficiency; your sleep is not as restful; you eat more, you gain weight; your relationships are affected,” he says.

As a result, our faces look, well, uglier. And puffier. But where does the puff come from?

Dark circles and bags appear when the body is unable to rejuvenate at night due to lack of sleep, says anesthesiologist, internist and bestselling author Dr. Michael Roizen, who compares puffy eyes to swollen ankles.

As we go through the day, we sometimes accumulate water in our bodies instead of passing it (as urine). The excessive water pools beneath the eyes, giving those telltale dark, puffy circles. If we don’t get enough sleep -- on our backs or sides -- our skin does not have the chance to refresh itself and tighten up.

"Normally when you sleep, you distribute water in the body," says Roizen, chair of the Wellness Institute at the Cleveland Clinic. Not sleeping causes us to accumulate water under our eyes, giving us that extra "baggage".

Roizen agrees with Sood that experiencing a lot of stress leads to lack of sleep -- and this can become a dangerous cycle. But stress does more than make people look weird.   

“What you get from stress is the wrinkles of aging,” says Roizen, who co-authored several bestsellers with Dr. Mehmet Oz, including YOU: Being Beautiful: The Owner’s Manual to Inner and Outer Beauty. “Stress causes you to age.”

Roizen also notes that stress not only causes wrinkles on the face but wrinkles in your arteries, as well, which can cause serious problems at an earlier age.

And the aging effect doesn't stop there.

“Your cells are biologically 10 to 15 years older … if you are chronically stressed," says Sood. "If you are 45, the cells signal as if they are 60 years old."

Both believe that reducing stress can enhance physical appearance and improve health.

“Stress and joy are two sides of the same coin,” advises Sood. “Engage with life and find meaning in it.” 

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