MobBoss said:Proof?
You can google it, there are many urls about it.
Here is one by the american journal of psychiatry:
http://www.prisoncentral.org/Prisoncentral/Mental%20Illness/Grassian/Psych%20Effects%20of%20Solitary/Index.htm
This is from the conclusions: "The present observations, coupled with those in the earlier German literature, suggest strongly that the use of solitary confinement carries major psychiatric risks. I have not attempted in this paper to define or classify this psychopathological syndrome, but, as mentioned earlier, there have been speculations in the literature linking solitary confinement with the formal experiments on profound sensory deprivation".