Debbie knows her grandson deserves to be in jail.

A few years ago, Gregor* attacked a stranger who was sitting quietly with his girlfriend, stabbing him six times in the back and neck.

"It was a shocking thing," Debbie says.

But she doesn't think Gregor deserves to be "doing his whole time" in solitary confinement, isolated and alone for at least 22 hours each day.

"They're human beings, they're not animals — animals get treated better," Debbie says.

Since Gregor turned 14, he's spent most of his time in juvenile detention or jail. When he stabbed the stranger, he'd only been out for eight weeks.

Debbie says Gregor has mostly been held in solitary confinement since he turned 18. He's now 25.

"He is starting to lose his sight a bit, which I reckon is through being locked down in isolation for so long. He doesn't get sunlight, there's no vitamin D," Debbie says.

"[There is] no rehabilitation or social workers or psychologists to check on these prisoners, [and] you can see mentally it's affecting him."

When Gregor was sentenced to 12-and-a-half years' jail for the attempted murder, the judge referred to his lack of remorse, but also his difficult early life.

His father died of a heroin overdose when he was two, and he was removed from his mum four years later. When he was eight he was sexually abused by an uncle. By 11, Gregor was living on the streets.

The judge noted that Gregor, then 22, had only spent nine months of the previous eight years out of custody.

Elle Jackson, a case worker with Jesuit Social Services (JSS), first met Gregor when he was 20.

She sees a connection between his solitary confinement and the escalation of his crimes — initially theft, stealing cars and joyriding.

"When you are a young person who has largely been in solitary confinement since you were 18, with limited access to any programs to address your offending or use of violence, I think that solitary confinement was a really big determining factor in this current offence," she says.

'Australians would be deeply shocked'

We don't know how many adult prisoners are held in solitary confinement, or for how long.

In a statement to RN, Corrections Victoria said the number varies on a daily basis, but each month "fewer than 2 per cent of male prisoners and 1 per cent of female prisoners" are in "restricted regimes".

JSS has today released a report focusing on the solitary confinement of 18 to 24-year-olds in Victoria. It calls for greater transparency and closer oversight.

The JSS report calls for: restricting solitary confinement to a maximum of 14 days;

restricting solitary confinement to a maximum of 14 days; daily review by a mental health professional;

daily review by a mental health professional; increased training for prison guards;

increased training for prison guards; the establishment of an independent custodial inspectorate;

the establishment of an independent custodial inspectorate; no prisoner ever being released into community directly from solitary confinement;

no prisoner ever being released into community directly from solitary confinement; the regular publication of statistics on the use and length of solitary confinement.

"We believe that Australians would be deeply shocked to find out what is actually happening in terms of the use of isolation," JSS CEO Julie Edwards says.

"We are seeing people across the age range ... who are spending extensive periods of time in isolation with very damaging consequences psychologically, physiologically."

Ms Edwards cites the case of a young Aboriginal woman who spent so much time in confinement that her muscles atrophied.

"[She] came from isolation directly out into the community. She didn't have the muscle tension to be able to walk around for any period of time, she had back pain," she says.

She knows of another man who essentially tried to confine himself after being released.

"We set him up in a house, he had actually restricted himself to the bathroom," Ms Edwards says.

"He was sleeping in the bath. He brought his radio in there, he had a kettle in there, and he was living in this very small bathroom because it resembled his cell.

"When he was in a public situation, he became agitated very easily, had panic attacks."

Former prisoner Harry* also struggled to readjust to life on the outside.

Harry says being in solitary confinement helped him get to a "good headspace". ( ABC RN: Damien Carrick )

Now 26, he's cycled in and out of jail for much of his adult life, and had a few stints in solitary confinement, usually for about a month at a time.

Surprisingly, he says he "grew to love" being in solitary confinement — he got off drugs and started exercising more, and was able to focus his thoughts.

"I started to depend on it because it was so easy for me," he says.

"I never was getting myself into trouble, I was in a good headspace, I was training every day.

"In there everything is so certain, it's safe."

But when he first got out, at the start of the year, he couldn't be in large rooms full of people.

"I couldn't be in cars ... that was real, real, real scary," he adds.

A complex issue

The JSS report isn't naive about the difficulties of handling serious violent offenders.

Presumably a prisoner is placed in solitary confinement if they are a danger — to other prisoners, guards or to themselves.

Debbie, for example, has heard that Gregor assaulted prison officers. She also mentions fights between prisoners.

"He gets out an hour a day, and if they bring out another prisoner there's a chance of them fighting because they don't know anything different than sitting in a little cell," she says.

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Corrections Victoria said the safe placement of prisoners, "some of whom are violent, display very difficult behaviour and have complex needs", is an "ongoing challenge".

It said solitary confinement is only used as "a last resort to ensure the safety and security of prisoners, staff, the prison and the community".

But Ms Edwards she has also heard anecdotal evidence of people being placed in isolation due to staff shortages, or a shortage in skills.

She says data on solitary confinement — including why people are put there — should be publicly available.

Ms Edwards says since Ireland started publishing data in 2013, the number of prisoners on so-called restricted regimes has decreased by 83 per cent.

"We think that's really significant," she says.

"When there is transparency, when there is accountability, when the public know what's happening, then the situation improves."

She says it's important to focus on rehabilitating prisoners.

"When someone is incarcerated, in this country, the deprivation of liberty is the punishment, and I think we should remember that.

"With that in place we should be doing everything we can to rehabilitate the person, the prisoner, to make sure that they never again offend like that."

Debbie hopes Gregor is able to get the skills and support he needs to make something of his life once he's released.

But at the moment, she says, that isn't happening.

"He's in solitary, he gets out an hour a day," she says.

"Where's their vitamin D? Where's their [exercise]? What are they learning in there? Nothing. Nothing to rehabilitate them before they come home.

"What's he going to do when he gets out here after 13 years?"

Corrections Victoria told RN it "recognises there are significant challenges in responding to the distinctive needs of young offenders".

"We are committed to working with young offenders to create positive behaviour change, and would welcome the opportunity to engage with Jesuit Social Services to provide them with a more detailed understanding of Victoria's prison system and the use of restricted regimes," it said.

*Gregor and Harry did not want their real names used. Because of this, RN was unable to ask authorities specific questions about their cases.