​ANZAC Day is one of the proudest celebrations of the year.

Watching our veterans march past is a stirring sight but spare a thought for the unseen injuries that so many carry.

Research funded by RSL Queensland and conducted by the Gallipoli Medical Research Foundation (GMRF), has found that military veterans with Post-Traumatic Stress Disorder (PTSD) are three times more likely to have a sleep disorder, twice as prone to stomach ulcers and four times more likely to have had a heart attack. This important $1.75 million, three-year study, is the world's first comprehensive study into the medical and psychological health of Vietnam veterans involving clinical and psychological evaluations of 300 Australian Vietnam veterans.

Post-traumatic stress disorder (PTSD), first so named in 1980, is a particular set of reactions that can develop in people who have been through a traumatic event. That is, they have experienced or witnessed an event which threatened their life or safety, or that of others around them, and led to feelings of intense fear, helplessness or horror. Individuals frequently experience "survivor's guilt" for remaining alive while others died. The military provides the most graphic example of exposure to traumatic circumstances that leave deep mental scars, and as shown in this RSL study, long term physical impacts as well.

PTSD is by no means limited to the military, Beyond Blue say that around 1 million Australians experience PTSD in any one year, and 12 per cent of Australians will experience PTSD in their lifetime. Serious accidents are one of the leading causes of PTSD in Australia.

As a military veteran from the 1970s, the improved understanding and focus on PTSD comes as a great relief to me. Relief, because it is actually a real, recognised, condition where the stigma has largely been removed. In those days there were no counselling services, discussions or education, in fact, it was a non-subject. We were expected to get on with it, toughen up, do the job. In my day it was called "malingering". I count myself as one of the lucky ones, but many of my friends have not been. The worst part they describe as living with something that was not tangible, like it was unique to them, something essentially wrong with their make up, an inherent weakness. Living with PTSD has taken a terrible toll on old soldiers and their families.

The important efforts by the RSL to fund PTSD research and support is to applauded.

During the Great War PTSD was called "shell-shock" in World War II, "combat fatigue". In RAF Bomber Command during World War II they created a unique term for PTSD, "Lack of Moral Fibre", to describe airmen who had lost the will to fight, those that were innately weak or cowardly, who cracked under pressure. The threat of being classified LMF was almost a tactic created to terrify aircrew into continuing the fight, it was the Sword of Damocles hanging over their heads. The subject of fatigue was completely taboo; airmen would not discuss their feelings with each other, much less the Medical Officers on the squadron. Even the slightest suggestion of going LMF was appalling, the fear of being regarded as inadequate, not measuring up to the pressures of war when your country needed you most. The combination of stress and pressure, the thought of imminent death, overlaying a sense of not wanting to let the rest of the crew down, with the overriding fear and disgrace of being branded as having LMF led many young men to suicide.

We have thankfully come a very long way since those dark days. The reality is however, if you put young men and women in harm's way, a certain percentage of them are going to be scared for life, physically and mentally. It is the very essence and consequence of war.

The US Department of Veterans Affairs says the number of Veterans with PTSD varies by conflict zone:

• Operations Iraqi Freedom (OIF) and Enduring Freedom (OEF): About 11-20 out of every 100 veterans (or between 11-20%) who served in OIF or OEF have PTSD in a given year.
• Gulf War (Desert Storm): About 12 out of every 100 Gulf War Veterans (or 12%) have PTSD in a given year.
• Vietnam War: About 15 out of every 100 Vietnam Veterans (or 15%) were diagnosed with PTSD in a 1980 study. It is estimated that about 30 out of every 100 (or 30%) of Vietnam Veterans will have PTSD in their lifetime.

In Australia Picking up the Peaces reports 56% of Australia's Vietnam War veterans have PTSD while it effects 31% of Australia's Gulf War veterans.

The RSL study involved assessment of veterans' blood pathology, heart disease and lung function assessments, abdominal ultrasounds and brain imaging. The research also involved tests on resilience, alcohol use, sleep habits, and diet.

It found Vietnam veterans with PTSD had a higher risk of sleep disorders, gastrointestinal problems and cardiac disease than service personnel without the condition. Sleep disorders are arguably one of the most debilitating. PTSD participants had a higher risk of REM behaviour disorder (3.8×), diagnosis of sleep apnoea (2.1×), restless legs (1.8×), and sleep disordered breathing (1.6×; due to reporting increased fatigue [2.6×]).

GMRF research director Professor Darrell Crawford presented the findings on 11 September at PTSD 2015, a forum held in Brisbane. Professor Crawford said the results revealed distinct physical symptoms in veterans with PTSD.

"When we compare participants with PTSD to those without, we find a greater risk of nightmares and sleep apnoea as well as bigger tendency for problems like irritable bowel syndrome, reflux, heart disease and respiratory problems,'' Professor Crawford said.

RSL Queensland State President Stewart Cameron said the findings of the Vietnam veteran study confirmed the importance of funding medical and scientific research into PTSD;

"The initial findings make public the significant physical effects of PTSD. This vital medical and scientific research will be ongoing and will play a role in best treatments of the disorder both now and in the future."

Key findings revealed veterans with PTSD have:

• More than triple the risk of acting out their dreams while asleep.
• Twice the chance of being diagnosed with sleep apnoea.
• Almost two times the tendency of restless legs.
• Increased daytime fatigue and sleepiness.
• Two times the chance of suffering stomach ulcers
• Double the chance of reflux
• Greater tendency to report constipation, diarrhoea and irritable bowel syndrome
• A four-fold higher risk of heart attack in the past
• Lower levels of the 'good' cholesterol which contributes to an increased risk of heart disease

All of this is not good news for present and future veterans, but at least it provides some basis for preventative measures. Hopefully veterans will be given access to more early medical testing and diagnosis. Access to services such as home care, allied health and mental health support at an earlier stage will help these important old soldiers, sailors and airmen and their families cope.

As is so often written, some of the hardest battles are fought long after the guns fall silent.