On Friday, UNC School of Law professor Deborah Weissman told a story about a prison inmate held in solitary confinement who struck up a friendship with a fly. “And when that fly left his cell, he broke down and wept,” she said.

It was just one of a number of stories told as law school officials and prison reform advocates gathered to call for an end to solitary confinement—a practice denoted as “torture” by the United Nations—in U.S. and North Carolina prisons. In most cases, solitary confinement indicates holding a prisoner in an isolated cell for 23 hours a day.

Prison officials say it’s used for various reasons, including as punishment or as protection for a mentally ill prisoner, although the confinement is believed by most psychiatric professionals to only exacerbate such an inmate’s condition.

Friday’s conference included a talk from Robert King, a Louisiana man who spent 29 years in solitary confinement for a false conviction. King was placed in isolation because he was a politically active inmate and a former Black Panther. “I was in prison seven years before I saw the sunshine,” King said.

In North Carolina, about 3,400 prisoners, or about 10 percent of the prison population, are held in solitary confinement at any given time, according to Christina Cowger of the N.C. Stop Torture Now advocacy group. Weissman said the U.S. was holding 80,000 inmates in solitary confinement in 2013, some as young as 14 years old.

The practice can have serious impacts on an individual’s mental health. Additionally, it costs twice as much as general confinement and has not been shown to help reform inmates. Studies in California and Colorado have found inmates held in solitary were much more likely than their general prison population peers to end up back in prison after their release, said ACLU of N.C. Legal Director Chris Brook.

However, change may be coming. Following the dehydration death of an inmate after a month-long stay in isolation last year, the N.C. Department of Public Safety has announced a number of reforms, including new policies and training, as well as the creation of an ongoing task force to prepare a policy on solitary confinement’s uses.

The inmate’s death also spurred the termination of nine prison workers and investigations by the N.C. State Bureau of Investigation, Disability Rights N.C. and a federal grand jury.

A report last November from the UNC School of Law called for an end to solitary confinement, describing it as a “cruel, inhuman and degrading form of punishment that is—or at the very least approximates—torture and a severe form of human rights violation.”

Brook said Friday that change is not farfetched in North Carolina, given that states as diverse as Mississippi, Colorado, Illinois and Maine have all begun reform efforts, most in response to lawsuits. “We have the opportunity here,” Brook said. “There are glimmers of hope.”