Have you ever wondered why, when you’re tired and stressed, you look a lot older than you actually are? Here’s the science behind what ages us – inside and out. Basically, when we’re stressed, we lose sleep, eat more, and gain weight. As a result, our body loses its ability to protect itself. That’s according to Dr. Amit Sood with the Mind Body Initiative at the Mayo Clinic. He says, chronic stress reduces the production of melanin, which is the pigment that gives your complexion color, and when you’re low on melanin, it can make your skin look haggard and yellow.

Chronic stress and sleep deprivation also reduce the production of collagen – the main protein in our skin that keeps it flexible, and smooth. And if you don’t have plenty of collagen, your skin begins to bag and sag. And those eye bags ARE a result of a lack of sleep. Normally, when we sleep, the excess water in our body drains away, allowing our faces to tighten up. But that doesn’t happen if you’re sleep-deprived. Instead, the excess water pools under our eyes, where it leaves dark, puffy circles.

But stress and exhaustion do more than just wrinkle our faces. They also wrinkle our arteries, which raises our risk for serious health problems at an earlier age, like heart attack and stroke. In fact, studies show that people who are chronically stressed have cells that are biologically 15 years older than their actual age. Which means, if you’re 45, your cells act like they’re 60.

What’s the fix? Find ways to reduce the stress! Experts recommend exercise. Even 30 minutes of walking a day can significantly reduce stress. And once you tackle the stress, your sleep will improve as a byproduct, and you’ll look better on the outside too.