Found these fascinating videos , they are excerpts from a BBC documentary, where they placed people in isolation ( in darkness) for 48 hours. Many started hallucinating. The Dr commented that in a lack of sensory environment, the brain stilll has to function, so it continues to create and work regardless.
So how helpful is solitary confinement for mentally ill one must ask? Many voice hearers will attest to the fact that isolation, and lack of sleep, and also late at night voices are often worse( when awake in the dark)
Here is the first http://www.youtube.com/watch?v=jfdN_megX4E&feature=fvwrel
in the second one you see them experiencing hallucinations http://www.youtube.com/watch?
The third one, they are tested afterwards, and their mental capabilities have deteriorated http://www.youtube.com/watch?v=2ewX-4eIomM&feature=relmfu