This researcher who studies self-injury explains why people do it. And why he did it.

What do you think of when you hear the words "self-injury?"

You probably think of a middle-class, teenage girl cutting herself to get attention. That's the cliché, and it's all kinds of wrong.

Meet Dr. Stephen Lewis.

He's been researching self-injury — we're most familiar with it as cutting or burning — for over 10 years.

A quick definition: Self-injury is intentional damage to body tissue (that doesn't include body modifications like piercings, tattoos, and scarification) without suicidal intent. And far more people are doing it than you'd think.

What he and other experts found might surprise you: Self-injury happens equally across gender, ethnicity, and socioeconomic lines.

It's not just an issue in the U.S. either. Self-injury has emerged as a major global mental health concern.

Here's something else that might surprise you: Lewis isn't just an academic expert. He's a life expert. He lived it.

He used to self-injure, and he shared his experience with the world in his talk for TEDxGuelphU.

It took some soul-searching before Lewis decided to tell his story publicly. In the end, he told me, "I wanted to convey a sense of hope to those who presently struggle. I wanted them to know they are not alone and that recovery is possible."

"There is light at the end of the tunnel. As dark as it may seem, if you keep walking — you can find it," he says.

Like Lewis (and myself), 1 in 5 adolescents has engaged in self-injurious behavior at least once, and a quarter of them have done it repeatedly. It can start as young as age 12.

As Lewis put it, "Self-injury provided needed relief from that emotional turmoil I was feeling inside. It conveyed the words I could not."

It's an attempt to relieve overwhelming feelings of sadness, distress, or self-loathing. Most often, people do it to externalize inner pain, to make it tangible, or to stop feeling numb.

The relief that self-injury provides is only temporary, though, and it can develop an addictive quality: The longer it's used, the harder it is to stop (or to find another way to quell the pain).

There's also a tolerance factor: The more you self-injure, the shorter the period of relief. It makes for a cycle that's incredibly difficult to break.

So, how can we help stop the cycle of self-injury?

Whether you're someone who has self-injured or not, one of the most important things we can do is educate ourselves: The false cliches and stereotypes we carry around about self-injury affect those who do it, too.

When we characterize people who hurt themselves as crazy, manipulative, or attention-seeking, they're more inclined to feel ashamed and isolated. They live in fear of judgment, and that fear creates silence.

This silence means that many people feel hopeless and alone. While self-injury isn't, by definition, a suicidal behavior, it does elevate risk for suicide.

Without help, that silence and that hopelessness can be deadly.

Self-injury is a habit that's hard to break. One of the first steps toward ending the cycle is for us to allow the conversation to happen.

Four little words are all we need: "How can I help?"

That's what turned things around for Lewis:

"For me, this involved a willingness to not just ask for help, but to accept it —something I was not accustomed to. This help, for me, came from professionals. It came from friends, and it came from my family."

His story ends well. My story — as a fellow self-injurer — ends well, too. All of these stories can end well.

"Recovery is a process," said Lewis. "And not a linear one. I had good days and bad days, and on some bad days, I self injured again. But those bad days became fewer and farther between."

Nobody should suffer alone. We all have baggage, but we each bear the weight of our burdens differently.

We can help each other bear that weight if we're brave enough to listen and brave enough to start conversations that matter.

This is how we find better ways to heal. This is how we create hope for those who need it the most.

Watch Lewis' full talk:

Want more information on self-injury? Take a look at the Self-Injury Outreach and Support website.