UK science communicator uses personal experience to highlight health issue that affects up to 90 Kiwis a day.
James Piercy calls it the "hidden disability".
Every year in his homeland, the United Kingdom, 135,000 people are admitted to hospital as a consequence of it.
And each day in New Zealand, about 90 Kiwis sustain it from everything from hypoxia and strokes to falls and concussions.
The UK science communicator is talking about brain injury, which he says for something remarkably common is poorly understood.
The gap is something Mr Piercy, who last night hosted a presentation in Dunedin as part of this week's New Zealand International Science Festival, aims to close.
Indeed, his own knowledge of brain injury was scant until the day his life changed - January 30, 2011.
What had been an ordinary Sunday outing near his home of Norwich turned to tragedy when his family's car sustained a tyre blow-out, spun off the road and slammed into a tree.
His wife Kate, 36, was killed on impact, and his three children, now aged 16, 13 and 8, suffered minor injuries.
Mr Piercy, the front-seat passenger, suffered a traumatic brain injury when his head slammed against the dashboard.
He recalls nothing of the accident and little of the weeks that followed. Emerging from a six-day coma, the news that his wife had died was forgotten an hour later.
Scans showed a small area of damage on the right side of his brain, causing weakness on that side of his body, but it was diffuse damage on the left that has meant the most problems.
"In most people, the parts of the brain that control your speech and language are on the left-hand side," he said. "When I get tired, I get a bit of a stammer, and I sometimes get stuck for words."
Fatigue, his heaviest burden, came on when he found himself growing stressed, anxious or trying to do too many tasks at once.
"Sleep helps, but it won't necessarily cure it, as does food. But the best thing I can do to recover is relax, stop trying to concentrate, stop worrying, and try convincing myself it will all be okay."
Brain-training activities such as reading books, playing games and socialising have also assisted his recovery.
"Basically, I've given up on the idea of getting back to the old James, and I've settled down on the idea of being the new James. I'm not constantly thinking about how far I've got to go, but how far I've come."
All the while, his need to understand his situation has seen much of his work as a science communicator with Science Made Simple focused on himself. He's learned about the critical parts of the brain, their key functions and, most importantly, how they communicate with each other.
Mr Piercy uses the analogy of a motorway being closed, and having to find other roads to reach his destination. "So what I've been doing the past three and a half years is re-wiring my brain," he said.
"The brain is plastic - when we learn things as babies, we are making connections, though the brain stays plastic for the rest of your life, and you can re-wire it."
Here, a healthy "cognitive reserve" helped, and research had shown that a longer period of education in life meant a better recovery from brain injury later.
By sharing his journey he hoped the knowledge he had been gathering may also benefit others.
"Lots of people with brain injury look perfect - you might think they're drunk, or mentally ill, but actually they're just really tired, or they have memory problems, or are anxious sometimes because they've had damage to parts of their brain."
James Piercy will give his "What's Going On In His Head?" public talk at Auckland Museum at 4pm this Thursday. To book tickets, visit Auckland museum website.