Castlerea Prison in Co Roscommon is dealing with an overcrowding problem, with 35 more inmates than it is supposed to accommodate.
There were 375 prisoners in the jail yesterday, which is significantly above its bed capacity of 340.
There is a similar problem in many prisons across the state, with 4,831 people behind bars around the country.
That is over 300 more than the normal limit, according to stats from the Irish Prison Service.
The Irish Prison Service says it must accept all prisoners committed by the courts and has no control over the numbers.
Former governor Mountjoy Prison, John Lonergan, says many inmates are forced to sleep on the floor.