Former rugby star Carl Hayman is speaking up about the dangers of concussion in the hope that current and future players won't have to endure degenerative brain conditions.
"Someone best described it to me as 'everyone's got a bucket of brain energy and yours is half full with holes in it," he tells Kathryn Ryan.
Carl Hayman is one of nearly 400 former rugby union rugby league and football players taking legal action against sports governing bodies on claims they suffered brain injuries during their careers. His book Head On: An All Black's memoir of rugby, dementia and the hidden cost of success will be published on 5 July.
Over a 17-year professional rugby career, Hayman played 45 tests for the All Blacks.
Now the 43-year-old wants to help prevent current and future rugby players going through the struggles with dementia and the degenerative brain condition CTE (chronic traumatic encephalopathy) that he now lives with.
Looking back, the first signs that something was wrong were emotional, Hayman says.
"I'd be talking in team meetings about rugby and find myself like welling up with almost tears."
He began to have headaches, insomnia and his short-term memory deteriorated.
"I just sort of thought to myself, well, you know, I need some answers and it'll just go away and I'll get on with my life."
The eventual diagnosis of brain injury and dementia came as a shock.
"I think I was in denial for quite some time. I didn't want to accept that. That's, you know, I didn't want to accept that diagnosis. And to my own detriment, probably I tried to carry on, as I normally would.
"For a long time, I didn't really accept that I had to start to live within these sorts of confinements, I guess you'd call them. I also thought of my kids - I've got four young children. You have this feeling of not really wanting to be a burden on anyone. There's a whole lot of thoughts that went through my mind once that diagnosis was given."
As Hayman's life started to unravel, he started to self-medicate with – "the worst means possible" – alcohol.
"it was just a real dark time in my life and unfortunately what I was dealing with did have a big effect on my family. That's the thing of dealing with something like this – it's not just myself, it's the people around me as well who to some extent, feel the effects probably more so."
Rugby authorities tend to have a "head in the sand" approach to concussions, he says.
"Talking about this and coming out in the media, I have been contacted by a lot of people, especially players who played in the '80s and some, even in the late '70s. And there's a, certainly a disproportionate number of players that are struggling with dementia, essentially. A lot of them are worse off than me and they find the same struggles, I guess."
During around 450 professional rugby games, Hayman reckons he endured tens of thousands of minor concussions, not including years of training sessions that were "pretty full on and pretty rough at times".
"'I think the thing with my case, it's the repetition of knocks to the head – not so much big concussions – that have done the damage here. So there has to be probably a real conversation about what's an acceptable level for these guys who are playing at the moment to play. 10 months a year is a long season so there's a lot of discussions to be had. A large motivation for me doing this and also writing this book was an obligation to players in the future.'
Dylan Cleaver, who Hayman worked with on the book, said it was important to be open and honest. Without people like him speaking out and also taking legal action, he feared not a lot would change for rugby players.
"We've seen some changes already from rugby authorities, like around the three-week stand down for concussions, so I think it's already having an effect on some of the decision-making.
"Even with the All Blacks given time away from Super Rugby, there is a bit of a difference there to minimise the window, to keep these guys fresh, and to look after them."
Today's rugby players are "bigger and faster and stronger" than those of the past, Hayman says, and as a result, knocks to the head have become stronger.
"One thing that would be nice to see would be some kind of monitoring about what guys are getting through in a year. We have some numbers on what's an acceptable level of risk to the players and I think the NFL put in some good things in the process around player passports, so players get a certain amount of impacts per year to use up and it's up to coaches to, to use them wisely.
"Ultimately, it's about the safety of the players. Unfortunately, it takes something like this to, to actually push change, so that we don't have another generation of players in say, 10 years' time, that are going to be exposed to the same experience."
Hayman says he feels an obligation to rugby players of the future that the dangers of concussion are talked about.
"Yes, it makes me a little bit vulnerable in terms of having all of this stuff out in the open, but I believe the bigger picture here is that we need to look after these modern-day players, and it needs to persist, especially putting some support in place for when these guys leave the game."