Her mother probably had post-traumatic stress disorder, or PTSD, she thinks, but because it was never treated she passed it down to the next generation.

One of Mary's siblings killed herself. Mary married an abusive man, and she thought she was to blame for the terrible way he treated her because she was conditioned, as a child, to accept abuse; that it was always her fault.

Her early years were full of shouting and fights, so noisy children trigger memories of being constantly terrified, making her either withdraw completely or lose her temper.

After two years of weekly sessions with a psychologist, she can function better and she hopes to start working or studying soon. Most importantly, Mary has not passed on her mother's legacy of complex trauma (a form of PTSD) to her own children because of the treatment she has received.

Jan*, a Sydney woman in her 30s now living in the US, grew up in a chaotic family. Her mother has bipolar disorder. Jan began therapy for depression in 2009, seven years after ending regular in-person contact with her mother, but it took a year before she accepted the therapist's suggestion that she had PTSD. "I had previously thought of PTSD as something suffered by war veterans or victims of severe physical abuse," she says.

Teacher Wendy*, from Hawaii, had the same reaction when she was diagnosed.

"I was in disbelief until I started researching it," the 29-year-old says. "Then I realised, this is me."

Since then Wendy has met 30 fellow sufferers, including nurses, lawyers, doctors and secretaries.

PTSD was first associated just with combat personnel, but research is uncovering how widespread it is. Triggering traumas include accidents, bushfires, strokes and heart attacks, surgery and being homeless.

The most common causes are sexual assault, domestic violence and motor vehicle accidents. The Australian Centre for Post-traumatic Mental Health (ACPMH) estimates 800,000 Australians have PTSD, and one in 10 will suffer from it in their lifetime.

Sessions with a psychologist are thought to be the best treatment. "The gold standard is 12 to 16 [sessions]," Sydney psychologist and trauma specialist Jay Spence says. Other experts put the number slightly lower or higher.

Complex PTSD can require many more sessions than this, yet the previous federal Labor government reduced the number of Medicare-funded sessions from 18 a year to 10 in January, for people older than 25.

An online petition by the Alliance for Better Access (ABA) pressure group calling for the cuts to be reversed has reached about 20,000 signatures. Campaigners hope a review of mental health policy by Coalition Health Minister Peter Dutton will restore funds for this service.

"Ten sessions is like having half a dose of antibiotics," ABA spokesman Ben Mullings says. "The symptoms go away for a little while and come back full force. You don't do half an operation. It's not on in physical healthcare and it shouldn't be on for mental healthcare either."

A paper in Psychological Medicine in 2012 says three-quarters of the 8841 people sampled for the 2007 national survey of mental health and wellbeing had experienced at least one potentially traumatic event; 7.2 per cent had developing PTSD; half had the disorder by age 26, and three-quarters by 42. The median length for remission was 14 years, but a third still had the condition after 30 years.

ACPMH director of policy and service development Andrea Phelps says two-thirds of Australians will be exposed to a traumatic event by age 16, leading to the group issuing its first guidelines for adolescent treatment.

"We used to think kids would be resilient," Dr Phelps says, "but it's probably been under-reported for some time."

One in 10 children caught up in the Tasmanian bushfires in 2012 showed mental health problems, including PTSD. A quarter of people who have had strokes or heart attacks develop the condition, and studies suggest women get PTSD at twice the rate of men.

Dr Spence sees five women for every one man in his practice. "The men I see are at a very severe stage of symptoms. Women are more likely to figure out something's going on when there's a good chance for it to be manageable."

Whether the cause is war, sexual assault or an accident, the clinical picture is similar. Women get more anxious, men more angry. There can be moodiness, withdrawal, anger, insomnia, nightmares and intrusive memories, sights, sounds and smells pitching them back into the traumatic incident.

This is all normal for the first two days, Dr Phelps says. The problems start when the symptoms persist and research suggests symptoms can take years to show. Anthony Parsons, from Melbourne, runs the MyPTSD.com website. ''You may have this really huge trauma early in your life. Later in life, it suddenly catches up with you," he says.

Candace*, 23, a Melbourne woman who is heavily pregnant, has a father who saw "no problem in belting the crap out of his kids". She ran away from home at 16, but soon got caught in a web of destructive relationships. One alcoholic boyfriend offered her to his dealer for drugs when he had no money. She was drugged and gang raped. Her PTSD surfaced briefly with another boyfriend during sex.

Then she was sexually assaulted while working as a trainee nurse. "Within two weeks I had really bad nightmares. I was screaming and thrashing around in bed." She was often unable to get out of bed for days on end and ground her teeth so badly while asleep that she chipped the enamel.

For Virginia*, a Sydney PhD student, it took seven years for her PTSD to roar to the surface after suffering six years of sexual abuse between the ages of 12 and 18. She is scared to leave the house in case she runs into her abuser and suffers chronic insomnia. She says she is "either too frightened to go to sleep or has disrupted sleep because of nightmares and flashbacks". Her studies are suffering as a result. ''Some people try and force themselves to live around the condition, or just not mention it and carry on, like the great Aussie battler," Dr Mullings says.

"That only gets you so far before it starts leaking around the edges."

Dr Spence says: "The main misconception people with PTSD have is that it's some kind of moral, intellectual weakness of capacity. That's part of the real insidiousness of it.

''People try to make meaning of the trauma by attributing a high degree of blame to themselves."

It can be hard for others to understand, he says. "PTSD is like a flaw in the alarm system that otherwise functions to keep us safe. It's run by the part of the brain trying to detect threats in the environment. Trauma changes the sensitivity of that reaction. Things that are a minor threat are perceived as an extreme threat."

Jack*, 48, a businessman who developed PTSD after serving in the Defence Force in East Timor, recalls meeting one woman at a support group. There had been an accident at her house in which people were injured, and despite not being there herself, she had "pretty extreme [PTSD], even compared to some military personnel", he says.

"She was on edge, highly reactive to small things and ready to snap like a mousetrap, with seemingly little awareness of how she was impacting on people around her. I was struck by the contrast to the very contained and dormant nature of most military people's PTSD."

Jack has been in weekly or fortnightly therapy for years, funded by the Department of Veterans Affairs, and says he is in a "reasonably good" place. Candace sees a psychiatrist up to twice a week, with unlimited access once she reaches the Medicare out-of-pocket threshold.

Not all sufferers want to take prescription drugs for PTSD, and psychiatric intervention is not always effective. This is where the funding limit of 10 sessions becomes a problem: the ABA quotes a study estimating half the people in therapy will show no change in that time.

''There's enough to get them back to a basic level of functioning, but cured of symptoms? Definitely not," Dr Spence says.

'The cuts actually hurt the people who are most in need," Dr Mullings says. He thinks 18 sessions are a "little on the low side".

"They can't afford it; they don't have private health cover or aren't covered by their insurance. A lot of people look at 10 sessions they now have and go, 'That's not sufficient for me, so what's the point of me starting?'"

Dr Mullings says there is only a "slim hope" the Coalition government will change the funding model.

A spokesperson for Mr Dutton confirmed all options were being considered and that the minister had said mental health care would be a priority in the first 100 days of his ministry - a deadline that ended on December 25.

Virginia now has to weigh up if she can afford the sessions she needs once she reaches the Medicare limit. Mary would like psychological therapy put on a par with psychiatric therapy, at 50 Medicare-funded sessions a year. "I feel very strongly that not funding Medicare access is a huge mistake, both socially and economically," she says.

* Names have been changed.

Visit The Australian Centre for Post-traumatic Mental Health (acpmh.unimelb.edu.au), Alliance for Better Access (betteraccess.net) for more information.