Human Rights Watch. Prison Conditions in the United States: A Human Rights Watch Report. 1991.

Visiting two supermaximum security prisons in Indiana, the Human Rights Watch examined inhumane treatment prisoners receive. The prisoners in those facilities spend an average of 23 hours a day in a small, often windowless cells, facing years of extreme social isolation, enforced idleness, and limited recreational or educational opportunities. The Human Rights Watch pays special attention to the treatment of those with pre-existing mental illnesses.