Top Highlights

• hallucinations, strangely, are not uncommon in those with blindness or impaired sight, and that these visions are not “psychiatric” but a reaction of the brain to the loss of eyesight. She had a condition called Charles Bonnet syndrome.
• Babak Boroojerdi and his colleagues, showed an increase in the excitability of the visual cortex when subjects were visually deprived, a change that occurred within minutes.
• The deafferentation tanks used in the 1960s produced not only visual deprivation but every other sort of deprivation: of hearing, touch, proprioception, movement, and vestibular sensation, as well as, to varying degrees, deprivation of sleep and social contact—any of which may in themselves lead to hallucinations.
• Hallucinations engendered by immobility, whether from motor system disease or external constraints, were frequently seen when polio was rampant.
• Sleep deprivation beyond a few days leads to hallucination, and so may dream deprivation, even with otherwise normal sleep. When this is combined with exhaustion or extreme physical stress, it can be an even more potent source of hallucinations.