The prison population of the United States is enormous with over two million individuals currently incarcerated nationwide. Nearly 80,000 of those are held in solitary confinement. They have no human contact and every element of their environment is controlled. Meals come through a slot in the solid steel door, as does all communication with prison staff. They might be allowed to shower once a week. They might not see the outdoors for months or years on end. They spend 22-24 hours a day in their cell with little to no human contact for days or even decades. The sensory deprivation they endure causes severe psychological damage. These people are invisible to us—and eventually to themselves. The UN has condemned solitary confinement. But it continues.