Updated

Two of America's leading advocates for prisoners' rights are urging state governments to abolish the use of solitary confinement for offenders under 18.

In a new report, Human Rights Watch and the American Civil Liberties Union say brief periods of isolation may be needed as a security measure. However, they contend that longer spans of solitary confinement can cause serious psychological and physical harm to young people, including heightened risk of suicide.

The report, "Growing Up Locked Down," said lack of detailed state data makes it impossible to estimate the number of juveniles subjected to solitary confinement and other forms of isolation at any given time. But it describes the practice as widespread, notably among juveniles held in adult facilities, and urges states to find alternatives.