The Effects of Solitary Confinement on the Neurological Processes of Inmates

Over 80,000 individuals in the United States are currently serving time in solitary confinement (American Friends Service Committee, 2021). For years, these inmates’ homes have been cramped 8×10 feet cells with nothing but a bed, a toilet, and a sink (UC Irvine School of Social Ecology, 2017). Solitary confinement is generally used as a correctional measure for offenses such as breaking prison rules, disrespecting correctional officers, or involvement in gangs. While in solitary confinement, inmates are generally held in their cells for 22 to 24 hours a day and are only permitted a few hours each day to walk around a small yard within the prison grounds. During their time in solitary, inmates are subjected to no-touch torture such as bright lights, extreme temperatures, and loud noises (American Friends Service Committee, 2021). These conditions along with a lack of human interaction cause inmates to struggle with lifelong mental illness and trauma. Amongst many other psychological symptoms, inmates in solitary confinement experience hypersensitivity to stimuli, hallucinations, and neurodegeneration. 

Figure 1. A standard solitary confinement cell is the size of a parking space and consists of a bed, a desk, a toilet, and a sink.

Solitary confinement inmates cite sensory deprivation and lack of environmental stimulation as the most difficult aspects of isolation. Individuals who are not exposed to a variety of stimuli experience impaired alertness which can result in two distinct outcomes (Grassian, 2006). The first is the inability to focus, a state which prison officials refer to as a “mental fog”. Inmates experiencing mental fog are unable to concentrate and struggle to recall their thoughts. A study of a women’s solitary confinement unit in the Federal Penitentiary found that many inmates were only able to perform tasks requiring mental energy for the first few hours of their day (Grassian, 2006). After these initial hours, they were unable to maintain attention or employ mental effort. The study also found that mental fog caused many of the women to experience severe anxiety and panic attacks.  The second possible consequence of lack of stimuli and impaired alertness is an inability to shift focus, also referred to as tunnel vision. An individual with tunnel vision becomes hyperfixated on one irritation such as a sound, sight, or smell. According to a study at a maximum security facility in Walpole, Massachusetts, over half of solitary confinement inmates reported inability to tolerate ordinary stimuli such as faucets running or lights flashing (Grassian, 2006). These stimuli, which would be insignificant to the ordinary person, cause alarm and extreme irritation among inmates. Hyperfixation can lead to psychotic disturbances, hallucinations of the stimuli, and delirium (Grassian, 2006).

According to psychiatrist Dr. Stuart Grassian, solitary confinement leads to severe hallucinations. While studying solitary confinement at Pelican Bay State Prison, Dr. Grassian found that hallucinations among inmates are extremely common, especially in those with preexisting psychological vulnerabilities such as anxiety, depression, or schizophrenia. A third of solitary inmates reported hallucinations of voices, smells, tastes, and violence. Stimuli that the inmate was already hypersensitive towards caused hallucinations which started as mild, but gradually developed, becoming more personalized and vivid. For example, during an interview for the Pelican Bay State Prison study, one inmate described seeing images of a tray of big pancakes being brought to their door. The big pancakes were then replaced with small pancakes that began to move around in a hitting motion. The inmate reported that they spent hours dwelling on if someone was trying to take their food away, as hunger was a stimuli they were already hypersensitive towards (Grassian, 2006). 

In order to understand the impact of isolation on brain activity, Richard Smyne, a neurobiologist from Thomas Jefferson University studied the effects of isolation on mice (Heng, 2018). Smyne began with intergenerational communities of mice. After a few months, he placed a group of adult mice into individual cages to represent the transition of inmates from general population to solitary confinement. After one month of isolation, Smyne and his team observed that the neurons in the mice’s brains had shrunk by 20%. However, the neurons had a higher density of dendritic spines — neuronal bodies which create synaptic connections. The increase in spine density proved that the mices’ brains were attempting to offset the neuronal damage by increasing the amount of synaptic connections within their brains. After three months of isolation, the number of spines eventually decreased, indicating that the brain damage done was unsalvageable. Scientists hypothesize that isolation leads to similar impacts in mice and solitary confinement inmates (Sanders, 2020). These results are worrisome, especially when considering cases where inmates remain in solitary confinement for years.

Figure 2. The amount of neurons, depicted by the green lines, had reduced by 20% after one month of isolation.

Despite its negative effects, solitary confinement is a common practice among most prisons in the United States (American Friends Service Committee, 2021). Inmates who experience such extreme isolation struggle with mental illness, hypersensitivity, hallucinations, and neuron damage.  For this reason, neuroscientists, activists, and the UN argue that solitary confinement for over 15 days is unjust and should be considered torture (Smith, 2018). However, most public policy officials have declared that solitary confinement cannot be abolished because of its impact on upholding prison safety (Ahalt et al, 2017). To reach an effective compromise, it is imperative for solitary confinement practices to be transformed. In 2018, the New York State Assembly passed the HALT act which outlines humane conditions for solitary confinement, eliminates the use of solitary confinement for inmates with pre-existing vulnerabilities, and restricts the use of solitary confinement to 15 consecutive days (New York State Senate). Activists believe that other states must follow New York’s precedent and pass legislation similar to the HALT act. In order to prevent irreversible mental damage of inmates, solitary confinement practices must be drastically transformed to create a less isolating and cruel form of punishment. 

Edited by Bushra Rahman


Grassian, S. (2006). Psychiatric Effects of Solitary Confinement. Washington University Journal of Law and Policy, 22(1), 327–380. 

Heng, V., Zigmond, M. J., & Smeyne, R. J. (2018). Neurological effects of moving from an enriched environment to social isolation in adult mice. Retrieved October 2, 2021 Brain Wellness and Aging: Pharmacological and Non-Pharmacological Interventions

Reiter, K., Ventura, J., Lovell, D., Augustine, D., Barragan, M., Blair, T., Chestnut, K., Dashtgard, P., Gonzalez, G., Pifer, N., & Strong, J. (2020). Psychological distress in solitary confinement: Symptoms, severity, and prevalence in the United States, 2017–2018. American Journal of Public Health, 110(S1). 

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Ahalt, C., Haney, C., Rios, S., Fox, M. P., Farabee, D., & Williams, B. (2017). Reducing the use and impact of solitary confinement in corrections. International Journal of Prisoner Health, 13(1), 41–48. 

UC Irvine School of Social Ecology. (2017, April 28). Hallucinations in an 8 by 10 cell: Do prisoners sent to isolation ever recover? | School of Social Ecology. Retrieved September 22, 2021, from 

Smith, Dana G. “Neuroscientists Make a Case against Solitary Confinement.” Scientific American, Scientific American, 9 Nov. 2018, 

The New York State Senate. “Senate Passes the ‘Halt’ Solitary Confinement Act.” NY State Senate, 18 Mar. 2021, 

Image Citations

Sanders, L. (2020, January 28). Loneliness is bad for brains. Science News. Retrieved September 22, 2021, from 

Agraharkar, Vishal. “The Use of Solitary Confinement in Virginia Is Inhumane and Unlawful.” American Civil Liberties Union, American Civil Liberties Union, 7 May 2019, 

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