There is general consensus among researchers that solitary confinement is psychologically harmful; indeed, research demonstrates that the clinical impacts of isolation can actually be similar to that of physical torture. In addition to increased psychiatric symptoms generally, suicide rates and incidents of self-harm are much higher for prisoners in solitary confinement.
A Culture of Harm: Taming the Dynamics of Cruelty in Supermax Prisons (2008), Craig Haney, Criminal Justice and Behavior, Vol. 35: 956-984
Beyond Supermax Administrative Segregation: Mississippi's Experience Rethinking Prison Classification and Creating Alternative Mental Health Programs (2009), Kupers et al, Criminal Justice and Behavior, Vol. 20, no. 10
How to Create Madness in Prison (2006) Terry A. Kupers, MD, MSP, in Humane Prisons, David Jones, Ed. (2006), Oxford: Radcliffe Publishing
Mental Health Issues in Long-Term Solitary and 'Supermax' Confinement (2003), Craig Haney, Crime and Delinquency, vol.49, no. 1
Patterns of Disturbed Behavior in a Supermax Population (2008), Lovell, Crim Just & Behav 35:985-1004 (results of survey of prisoners in Washington's supermax facilities)
Prison Punishment Exacerbates Inmates' Psychiatric Illness (2005), Eve Bender, Psychiatric (Vol. 40, no. 21, p. 15)
Psychiatrists Decry Punishment That Isolates Prisoners (9-03-10), Rich Daly, Psychiatric News (Vol. 45, no. 17, p. 4)
Solitary Confinement and Mental Illness in U.S. Prisons: A Challenge for Medical Ethics (2010), Metzner & Fellner, J Am Acad Psychiatry Law 38:104–8.
Supermax Prisons and the Psychological Effects of Isolation (2008),
The Psychiatric Effects of Solitary Confinement (2006), Stuart Grassian. J Law & Policy, Vol. 22:325 (prepared from a statement given to the Commission on Safety and Abuse in America's Prisons).
The Psychological Effects of Solitary Confinement on Prisoners in Supermax Units Reviewing What We Know and Recommending What Should Change (2008), Arrigo & Bullock, Int J Offender Therapy & Comp Criminology, vol. 52, no. 6 622-640
The Psychological Impact of Incarceration: Implications for Post-Prison Adjustment (2002), Craig Haney
What To Do With The Survivors? Coping With the Long-Term Effects of Isolated Confinement, Terry A. Kupers, MD, MSP, in Criminal Justice and Behavior