Some inmates were forced to stay in their cells for 30 hours during the pandemic, according to a report from the Inspector of Prisons and Maynooth University.
It reveals how they had to eat their meals out of cardboard boxes.
The report focused on the impact that compulsory 'cocooning' had on prisoners.
There has not been a single case of Covid-19 in Ireland's prisons, but this report found the measures took a toll on inmates.
In mid-April, the Red Cross sent 86 journals to most people who were cocooning, such as those over 70 or with serious medical conditions.
Prisoners claim they were forced to eat meals out of cardboard boxes, which was "dehumanizing".
Office of Inspector of Prisons and @MaynoothUni Briefing 'Ameliorating the impact of cocooning on people in custody' is available here - important to note the open engagement by @IrishPrisons in this project @IPRT @DeptJusticeIRL: https://t.co/Jlb8XRXmnX— Fíona Ní Chinnéide (@fianna71) July 29, 2020
Some claim they were not able to go to the exercise yard for up to 30 hours to get fresh air.
They say mental health was already the main issue in prison and Covid-19 worsened that.
The report said lessons should be learnt on how to lessen the suffering of prisoners if there is a second wave and public health restrictions are reimposed.