Ulrike Meinhof was put in the so-called "dead wing" at Cologne-Ossendorf prison, where Astrid Proll had previously been held. In order to ensure the women remained separate, Proll was transferred to the men's wing.

The "dead wing" was intended not only to isolate, but also to induce a breakdown through sensory deprivation torture. It consisted of a specially soundproofed cell painted bright white with a single grated window covered with fine mesh, so that even the sky could not be viewed properly. The cell was lit twenty-four hours a day with a single bald neon light. It was forbidden for the prisoner to hang photographs, posters, or anything else on the walls. All other cells in the wing were kept vacant, and when other prisoners were moved through the prison--for instance, to the exercise yard--they were obliged to take a circuitous route so that even their voices could not be heard. The only minimal contact with another human being was when food was delivered; other than that, the prisoner spent twenty-four hours a day in a world with no variation.

The use of sensory deprivation had been studied by doctors in Canada and the United States since the late 1950s, the line of research being taken up in the FRG by Dr. Jan Gross of Hamburg's Eppendorf University Hospital. Studies carried out by Gross found that sensory deprivation consistently caused feelings of unease ranging from fear to panic attacks, which could progress to an inability to concentrate, problems of perception (including hallucinations), vegetative disorders including feelings of intense hunger, chest pains, disequilibrium, trouble sleeping, trembling, and even convulsions.

[The Red Army Faction: A Documentary History, introductory texts and translations by André Moncourt and J. Smith]