Measures introduced to deal with the Covid-19 pandemic led to an improvement in Irish prison standards last year, according to the Irish Penal Reform Trust.
Like other congregated settings, Irish prisons have faced huge challenges due to Covid-19.
During the first wave last year, a reduction in prisoner numbers and cell sharing kept the virus at bay.
Family visits were substituted with video calls and there was a provision for phones in cells.
These approaches have been welcomed by the Irish Penal Reform Trust, in its fourth annual review of Irish prison standards.
However, it said, as the country's oversubscribed courts system prepares to clear a backlog, any improvements are at risk of being reversed.
IPRT Executive Director Fíona Ní Chinnéide said there were more than 4,200 prisoners in custody at the outset of the pandemic.
She said within a month of the pandemic being declared, the Irish Prision Service reduced that population by 10%, which led to the "near-end" of prisoners sleeping on mattresses on floors and a move to single-cell occupancy.
She said the response to the pandemic "demonstrates that the majority of closed prisons across the State were overcrowded and unsafe in the first instance. It also suggests that prison was not a necessary sanction for all of those imprisoned before the pandemic hit."
The report also found that little progress was made in addressing mental health in prison.
Ms Ní Chinnéide said that in any given month through the first half of 2020, there were anything from 21-33 very unwell people being incarcerated in prisons due to a lack of access to community hospitals or space in the Central Mental Hospital.
We need your consent to load this rte-player contentWe use rte-player to manage extra content that can set cookies on your device and collect data about your activity. Please review their details and accept them to load the content.Manage Preferences
The report also found that short sentences are particularly prevalent across the female prison population, with up to a third of those in prison in 2019 and 2020 serving sentences of 12 months or less.
More than half of the female prison population in the Dochas Centre at Mountjoy Prison were cocooning in the early stages of the pandemic because of underlying health conditions.
The IPRT said Ireland must learn from progressive penal policies such as in Scotland.
A gender specific women's supported bail service there helps keep them out of prison by addressing issues that contribute to addiction, mental health, housing and homelessness.