Sometimes, things can change in an instant. A slim 13-year-old Grade 7 can step out of his classroom and be struck by the bigger, bulkier, stronger Grade 8 sprinting bullishly down the hall. The Grade 8, shoulder at the level of the Grade 7's head, can make clean contact with the side of the younger boy's skull, forcing it to snap and spin back into the brick wall behind him before he crumples to the floor.

Head meets shoulder, wall, and floor, in the blink of an eye.

Maybe, even, the younger boy could be knocked out by one of the three blows, eyes rolling back into his head.

Maybe, even, an ambulance might need to be called in order to pick up the trembling boy, only the whites in his eyes showing.

Maybe, even, when the boy regains consciousness, his vision and depth blur in and out for hours on end while he is strapped to a backboard with a neck brace at a busy hospital by helpless, apologetic paramedics just following procedures.

Maybe, years later, after nearly half a decade of blackouts and neck pain, the boy could grow to be symptom-free, only a hand tremor to show for it.

Maybe, even, it could have been his fifth concussion. This time, it was really serious.

The younger boy was me.

Unable to control my eyes, wading in and out of consciousness, accompanied by the principal, the teacher who'd scooped my limp body onto a rolling chair and down the elevator, and a crying, much bigger child standing over me. Ironically, he was running to get an ice pack for a friend.

Despite the problems that followed, I was lucky. A family member and later my girlfriend were usually there to steady me when I'd black out. I was forced to quit playing contact sports (lacrosse and hockey) permanently. I had to visit the odd neurologist or go through the odd CT Scan. I visited a therapist for neck tightness. It could have been a lot worse.

Imagine taking the equivalent of those simple blows on a nightly basis. For some NHL players, even those who don't fight, this isn't far from their reality, according to Dr. David M. Reiss, a psychiatrist who has published studies such as "Head Injury, Stress and Reactions to Medications and Drugs," and presented talks with names like "Trauma and Emotional Stress in Contact Sports: Psychological and Interpersonal Costs."

"It is particularly important to recognize the vulnerabilities of athletes who are inherently exposed not only to physical injury, but also to both acute and chronic pain and related personal, interpersonal and psychosocial stresses."

- Dr. David M. Reiss in his paper on traumatic brain injuries (TBI) and chronic traumatic encephalopathy (CTE), titled "Head Injury, Stress and Reactions to Medications and Drugs"

"When you’re talking about a hockey enforcer, particularly with their head getting hit, if they’re getting their head banged around two or three times a night, you can’t guarantee there’s going to be problems but they’re setting themselves up for problems," Reiss said a phone interview. "And there’s no predicting whether that will be one year, five years, 20 years down the line, we just don’t know enough."

And enforcers aren't the only ones susceptible to these problems. According to Reiss, one long-time NHL all-star he worked with is now feeling cognitive effects in his 50s, years after retirement.

"Just like we’re seeing in football, where the linemen these days are bigger, stronger, faster, basically every collision is like a 30-mile-an-hour car collision, you’re having micro collisions on every play," he said, adding that these plays lead to micro concussions that compound, even without knowing it.

Our understanding of the seriousness of these injuries has come a long way too. According to Reiss, we aren't as ignorant as we once were.

"When I did sports medicine, unless someone lost consciousness, it wasn't even considered a concussion," Reiss said. "Now we know that any time the brain is affected it’s a concussion and we’re realizing that both minor concussions where someone may not lose consciousness still can do damage, particularly if it’s repetitive."

"At times, even instances where a person may not notice, it may still be causing cumulative damage."

Still, there remains a lack of awareness, despite the progress.

"We’re still way behind," Reiss said. "A lot of it goes against what we were told was scientific in the past and was common in the past and what we’re seeing now is we really didn’t understand the situation well at all."

What's most important, Reiss said, is rest.

"Where it used to be, well, if you feel ok and no neurological signs, go out. Well, now we know if you've been dinged, it’s best to take a couple weeks off and let your brain heal," he said. "And of course the younger the person is, the more important it is."

For athletes at the highest level, the impact of these injuries can be career threatening, leading to a host of problems for young and middle-aged men. Beyond the physical effects, the mental trauma can be crippling. And it's twofold.

"On one hand, we know for a fact that a head injury can of itself cause depression and can cause a slowness of cognition and thinking as well as impulsivity, you have the direct neurological effects," Reiss said. "But then you also get, especially if it’s a younger guy who loses their career, or just isn’t functioning well, and they lose their career because they can’t stay at a top level as long, you get these situational depressions from just not having a plan B of what to do with their lives, being depressed about where their career went."

On top of this, because of the head injury, they’re less capable of coping with these issues, according to Reiss, particularly when you add the chronic pain that comes with playing a competitive contact sport.

"A lot of the pain medications -- and somebody doesn’t have to be addicted or abusing it but even just taking what could be considered a normal medication -- on top of a head injury, can actually lead to more impulsivity, more depression," he said quietly. "One of the problematic things is that the medications we often use for depression don’t work the same way with someone who has had a head injury and can sometimes actually make it worse in the long run."

Due to the host of neurological effects, situational depression, lack of successful treatments, and pain, it can become a careful balancing act.

"You take someone who has maybe some degree of head injury, some degree of situational depression, on a couple medications, you don’t have to add in much alcohol or an elicit drug or an argument with a significant other and you can reach a tragic point very quickly," Reiss said.

There are some tangible things an athlete can do to help themselves, but there needs to be a proper support system in place to facilitate it.

The biggest things are education, seeking help, and meeting with doctors that know it's complex, Reiss said.

But there's more to it too.

"We know some of the best things you can do is watch your weight, stay fit, watch your diet," he said. For athletes that are elite level hockey players, this generally isn't a problem. But what about when their careers end so suddenly and unexpectedly?

Professional hockey players past and present, ranging from former all-star Bernie Nicholls, to current players such as newly signed Toronto Marlies forward Rich Clune and Daniel Carcillo, have recently written about the struggles players face with mental health.

"I had a tremendous hockey career, but it was extremely detrimental to my health and mental well-being," Nicholls wrote in the NY Daily News. "It’s long past time for the NHL to come to terms with its past, care for its alumni and ensure the game is safe and prosperous for years to come."

"When you finally pull on that NHL sweater, you put on the mask to deal with that ever-present fear that it could all go away in an instant," Clune said in his piece with The Players' Tribune about addiction.

"My best friend in hockey, Steve Montador, was found dead in his home at age 35. Steve was a 12-year NHL vet who battled addiction at certain points in his career before getting sober," Carcillo said in Gone. "Since he walked away from the game due to concussions in 2013, he was struggling to figure out what to do next."

Reiss, having also worked in sports law, argued there should be resources in place for the game's alumni. And not just for professional athletes.

"From the school level up to the league, somewhere there should be some responsibility," he said. "For college players who sometimes after they leave college have nothing, it’s the guys who don’t make it because they weren’t good enough, they weren’t fast enough, and they were the ones taking most of the hits, who maybe after college actually have more damage that no one even recognizes."

The confusion in the legal process, on several issues, it what makes change slow. Should the league or the players' association cover availability for mental health for alumni?

With regards to head trauma, what did the league know? What didn't the league know?

"There’s some information that no one knew, there’s some things that truly were covered," Reiss said, adding that there's so little availability that people will call him from around the world just to find other people to talk to that have been through the same things.

At the lower levels of sport, the infrastructure doesn't even have the proper funding to begin to be put into place.

Organizations such as the Canadian Centre for Ethics in Sports still struggle to get proper funding from government agencies, like Sport Canada, for programming tools for communities that address concussions, President and CEO Paul Melia told me in an interview in November.

Even in today's billion-dollar industry, the professional, college, or junior hockey player who has been travelling from age 16 to age 40 -- if he's lucky -- and taking a beating on a nightly basis, isn't afforded the comfort of home, family, friends, and doctors, that that Grade 7 was.