On Saturday night, the world was rocked by a mass shooting that unfolded at Pulse nightclub in Orlando.
For Nesan Kistan, the news evoked a trauma that is engrained in his memory.
"I heard about it, and then I saw the images... over and over again.
"Those images were a trigger. Instantly you remember that day, that time. You remember being in that space. And all of the memories that you experienced in that heightened period of time -- from the sounds to the smells -- are evoked all over again. Very powerfully."
Traumatic events don't get put to bed. There are some wounds that you will always carry.
On April 28 1996, Nesan's parents were holidaying in Port Arthur.
His father Tony was one of the first people killed when mass murderer Martin Bryan stormed the Broad Arrow Cafe at the historic site in Tasmania. His mother was in the cafe and saw the tragedy unfold.
Nesan was listening to a Ray Hadley football report when news broke.
"That day is one that I will always remember," he told The Huffington Post Australia.
"Living with trauma and living with the consequence of someone close to you dying as a result, is something that doesn't leave you. That level of trauma has continued to impact our family every single day since."
The 'Stand Tall 4 PTS' campaign
Nesan Kistan is joining others living with Post-Traumatic Stress Disorder (PTSD) to champion a national convoy that is set to raise awareness about a condition affecting more than one million Australians.
The 'Lightning Bolt' convoy is an initiative of 'Stand Tall 4 PTS,' a campaign set up by former Australian Test cricketer, Vietnam War veteran and PTSD advocate, Tony Dell.
Launched at Suncorp Stadium in Brisbane on Tuesday, the convoy will see a bank of 40 first responder vehicles, police cars and WWII reconditioned jeeps make the journey to Melbourne over two weeks. The aim? To shine a light on and debunk the misconceptions surrounding a disorder that is widespread, yet often misunderstood.
"This is a condition that people develop after they have been exposed to some form of horrific event," Director of the Centre for Traumatic Stress Studies Professor Sandy McFarlane told Huffpost Australia.
"This event becomes imprinted in a person's mind in a way that the attached memories intrude and play upon their consciousness, causing significant stress -- for example through nightmares or flashbacks where a person really feels transported back to a time and place."
What follows is an enduring pattern of "hypervigilance", resulting in poor sleep, increased irritability and social disengagement that can profoundly impact the daily life of its sufferers -- sometimes years after a trauma taking place.
People need to be aware that so many people are affected by this. The residual impact of trauma is widespread, and it can impact people at various points of vulnerability.
"This is a mental health injury that is invisible -- and it is one where people assume that, with time, you should be able to move on with your life," Kistan said.
"It doesn't work that way. Traumatic events don't get put to bed."
Earlier this year, Nesan and his family mourned twenty years since the Port Arthur Massacre.
"My mother's whole body shut down. She had to be hospitalised. Every few years, or when another tragedy takes place, she suffers. And there's nothing we can do to change or undo that.
"There are some wounds that you will always carry."
According to Professor McFarlane, PTSD sufferers extend further than military veterans who have experienced combat-related trauma.
"People may have been the victims of traumatic events themselves, or they may have experienced events such as combat or natural disaster," he said.
"Equally, emergency services personnel who attend and witness these events carry significant risk for the benefit of the community, but the costs and burden that they carry into their personal lives is often minimised."
As a consequence, mental health services often fail to provide the specialist care that PTSD sufferers require.
And this is a common misconception.
"People need to be aware that so many people are affected by this. The residual impact of trauma is widespread, and it can impact people at various points of vulnerability," Nesan said.
"We are seeing the level of suicide going to extraordinary heights -- and a growing number are a direct result of PTSD."
Nesan -- who now works as a police chaplain for the NSW Police Force -- hopes the convoy will raise critical awareness.
"I think we need to start to recognise that we as a society need to take some responsibility for what is impacting so many vulnerable people."
The 'Stand Tall 4 PTSD' convoy will stop in a number of towns and cities along the east coast before finishing up in Melbourne.