Solitary confinement does not work by most measurable outcomes. It fails to reduce violence inside prisons, increases the likelihood that released inmates will reoffend, causes severe psychiatric harm, and costs significantly more than standard housing. On any given day, roughly 81,000 people sit in solitary confinement in U.S. federal and state prisons, about 6.3% of the total prison population, despite decades of evidence that the practice undermines the very goals it claims to serve.
What Solitary Confinement Is Supposed to Do
The rationale for solitary confinement rests on three claims: it deters inmates from violent or disruptive behavior, it protects staff and other prisoners from dangerous individuals, and it makes communities safer by punishing the worst offenders more harshly before release. In practice, the evidence runs against all three.
It Increases Reoffending After Release
The most direct test of whether solitary confinement “works” is what happens when people get out. A large Colorado study tracking over 3,000 prisoners held in solitary between 1995 and 2003 found that those released directly from isolation to the community had a three-year recidivism rate of 66%. Prisoners who spent time in solitary but transitioned back to general population before release reoffended at 60%. Those who were never in solitary reoffended at 50%. The pattern is clear: solitary confinement makes people more likely to commit new crimes, not less.
A separate matched study comparing isolated and non-isolated prisoners found that 24.2% of those held in solitary were later reconvicted of a violent crime, compared to 20.5% of those in general population. The researchers concluded that solitary confinement is associated with an increased risk of violent recidivism specifically. People released from isolation also reoffend more quickly than those who had at least three months back in general population before returning to the community.
It Does Not Make Prisons Safer
Rates of self-harm, assaults on staff, and suicide are all significantly higher in solitary confinement units than in general population housing. In New York, the suicide rate among prisoners in solitary is five times higher than among those housed normally. More than 60% of youth suicides in correctional facilities occur in solitary confinement. A New Jersey study found that single-cell detention carried a suicide rate more than 400 times higher than double-cell general population housing, and 23 times higher than the prison system’s overall rate. Of 26 prison suicides tracked over a seven-year period, 20 occurred in segregated housing.
The strongest evidence that solitary confinement doesn’t improve institutional safety comes from what happens when prisons stop using it. Mississippi reduced its solitary confinement population by more than 80% and moved prisoners with serious psychiatric conditions to treatment-oriented settings. The result was a 70% decrease in prison violence. Removing people from isolation made the facility less dangerous, not more.
Severe Psychological Damage
Half of the people studied in solitary confinement units show clinically significant symptoms of depression, anxiety, or guilt. About one in four experiences clinical-level depression. Nearly one in five has attempted self-harm, and 22% have attempted suicide. The rate of serious mental illness in solitary populations runs around 19%, far higher than the general prison population.
In qualitative interviews, 80% of people in solitary described the emotional toll as severe, and 73% reported profound feelings of social isolation. One in four described a loss of identity, a sense of no longer knowing who they are. About 16% reported sensory hypersensitivity, where ordinary sounds or lights became painfully overwhelming. These are not temporary discomforts. They are psychiatric injuries that persist after release and make reintegration into society harder.
Physical and Neurological Harm
Prolonged isolation does measurable damage to the brain. Neuroimaging research shows that social isolation is associated with shrinkage of the hippocampus, the brain region central to memory and learning, and the same area that deteriorates early in Alzheimer’s disease. Isolated individuals also show reduced thickness in areas of the cortex involved in decision-making, spatial awareness, and processing social information. The longer isolation continues, the more pronounced these changes become.
The body suffers too. Chronic isolation raises cortisol, the primary stress hormone, which over time impairs immune function, increases the risk of cardiovascular disease and stroke, and contributes to high blood pressure and Type 2 diabetes. People in solitary confinement have almost no access to natural light or physical exercise, compounding these risks. The combination of neurological deterioration and chronic stress-related disease means solitary confinement can shorten lives well beyond the period of confinement itself.
It Costs More, Not Less
In California, housing a prisoner in general population costs about $106,000 per year. Solitary confinement costs at least $125,000, an 18% premium. That gap reflects the additional infrastructure, staffing, and security required to keep someone locked in a cell for 22 to 24 hours a day. Multiply that premium across tens of thousands of prisoners nationwide, and the price tag for a practice that worsens outcomes is enormous.
Alternatives That Show Better Results
Step-down programs, which gradually transition people out of solitary into less restrictive settings with structured programming, have been tested experimentally. The results show that housing people in less restrictive conditions produces no increase in violent or nonviolent misconduct once they return to general population. In other words, the tight control of solitary confinement adds nothing in terms of behavioral improvement. People do just as well, or better, with a structured transition.
Mississippi’s experience is the most dramatic example. By replacing mass solitary confinement with mental health treatment and less restrictive housing, the state saw violence drop by 70% while saving money on reduced staffing and infrastructure needs. Other states have followed with similar reforms, motivated by the converging evidence that solitary confinement makes prisons more dangerous, communities less safe, and people sicker at greater public expense.
Why It Persists
If solitary confinement fails on every metric, the natural question is why it remains so widespread. Part of the answer is institutional inertia: prisons have used isolation for over a century, and correctional systems are slow to change. Part of it is political. Appearing “tough on crime” is easier than explaining the evidence to voters. And part of it is practical. When a violent incident happens, moving someone to a cell feels like doing something, even if the data shows it makes the next violent incident more likely. The gap between what feels effective and what is effective explains much of solitary confinement’s persistence.