At the same time, a report by the American Civil Liberties Union of Ohio criticized the privately operated prison for overcrowding it says is causing an increase in fights and attacks on guards.
The restriction involved one of three housing units at the 1,700-inmate Lake Erie Correctional Institution in northeast Ohio, about 25 miles from Erie, Pa.
Spokesman Steve Owen with Corrections Corporation of America in Nashville, Tenn., said one inmate injured in a fight required hospital treatment and was returned to the prison. Owen said the fights were unrelated and each involved a handful of inmates.
The CCA-owned and operated prison sold by the state houses inmates under contract with Ohio.
"The entire facility is at full, normal operations," Owen said in an email Tuesday night.
The bunk restriction in the dormitory-style unit required inmates to remain on their bunks unless accompanied by a guard to the bathroom or elsewhere, Owen said. The restriction allowed time for prisoners to settle down and for the fights to be investigated, he said.
The ACLU said in the report that inmate fights and attacks on guards are up sharply at the prison since the private takeover and the report blamed overcrowding.
The state prison became the first in the nation to be sold to a private company in a $72.7 million deal announced in 2011 by the administration of Gov. John Kasich in a budget-balancing move.
A separate unit of the prison for troublesome inmates is at 130 percent of capacity, with some cells holding three inmates and some sleeping on the floor, according to the ACLU.
The ACLU report said a February audit of the prison by the Correctional Institution Inspection Committee found inmate assaults on other prisoners rose 180 percent and inmate attacks on staff members jumped 300 percent from 2010-2012.
The ACLU sent a timeline to state lawmakers on the first 18 months of private operation of the prison and called for safety improvements.
"This facility has become unsafe for inmates, employees and the surrounding community," said Mike Brickner, director of communications and public policy for the ACLU of Ohio.
Owen, the CCA spokesman, criticized the ACLU for going "to any length to attack our company."
He said a recent Ohio Department of Rehabilitation and Correction report said the prison was complying with every standard within its control. In addition, the American Correctional Association recently gave the facility a nearly perfect score following a 72-hour review, Owen said.
Owen said the company is proud of the services it provides at the prison.