Solitary confinement is the practice of holding someone alone in a cell for most or all of the day with minimal human contact. It is among the most contested practices in corrections, and one of the oldest — it was invented as a reform.
Solitary confinement was not originally conceived as a punishment. It was introduced as a cure by the nineteenth-century prison and asylum reform movement, whose Pennsylvania system held that isolation would produce penitence. The harm it caused was documented within a decade.
Key Takeaways
- Solitary began as a nineteenth-century reform intended to produce penitence, and harm was documented almost immediately.
- Prolonged isolation is strongly associated with serious psychological harm.
- People with existing mental illness are more likely to be placed in it, and most likely to be damaged by it.
- It goes by many administrative names — restrictive housing, segregation, special housing units.
- Reform efforts focus on duration limits, exclusions for vulnerable groups, and alternatives to isolation for managing behaviour.
It Was Invented as a Reform
The Pennsylvania system, expressed most fully at Eastern State Penitentiary from 1829, held prisoners alone with a Bible on the theory that solitude and reflection would produce genuine repentance. It was intended as a humane advance on corporal punishment.
Observers documented psychological deterioration among prisoners at the time. The system was eventually displaced by the cheaper Auburn model, but the practice survived. This history is worth knowing because it is a clear case of a reform producing harm its designers did not intend — see prison reform in the 1800s.
Why It Is Used
- Discipline — as a sanction for rule violations
- Protective custody — for people at risk from others, sometimes at their own request
- Security management — for those assessed as a threat to staff or other prisoners
- Administrative segregation — pending investigation or transfer
The protective custody case is the genuinely difficult one: someone at real risk may be safer isolated, which means the alternative to isolation cannot simply be exposure to that risk.
The Documented Effects
Prolonged isolation is associated with anxiety, depression, difficulty concentrating, sleep disruption, and in some cases hallucinations and paranoia. Effects are more severe with longer duration and for people with existing mental illness.
There is a compounding problem. Symptoms of mental illness — agitation, non-compliance, self-harm — can be recorded as disciplinary infractions, which lead to isolation, which worsens the symptoms. See mental health in prison.
What Reform Proposes
- Duration limits — capping consecutive days in isolation
- Categorical exclusions — for young people, pregnant women, and those with serious mental illness
- Mandatory clinical review before and during placement
- Step-down units providing a graduated route back to general population
- Out-of-cell time minimums and access to programming
- Behaviour management alternatives that do not rely on isolation
The opposing argument is a practical one from corrections staff: facilities must be able to separate people who are genuinely dangerous, and removing that tool without funding an alternative shifts risk onto staff and other prisoners. Reform that ignores this tends not to survive implementation.
Frequently Asked Questions
What is solitary confinement?
Holding someone alone in a cell for most or all of the day with minimal human contact. It is also called restrictive housing, segregation, or special housing depending on the system.
What does solitary confinement do to a person?
Prolonged isolation is strongly associated with anxiety, depression, concentration and sleep problems, and in some cases hallucinations and paranoia. Effects are more severe with longer duration and among people with existing mental illness.
Why was solitary confinement created?
As a nineteenth-century reform. The Pennsylvania system held prisoners in solitude on the theory that reflection would produce penitence, intended as a humane alternative to corporal punishment. Psychological harm was documented soon afterwards.
Sources & Further Reading
Last reviewed August 2026.
Part of our complete guide to prison reform.