It may be that people recover normally with some sleep, however if you don't get that sleep you will die (after you start to hallucinate and then that progresses to dementia). Fatal familial insomnia, is named Fatal for a reason.
I think the other point here is that it's physically impossible to stay awake long enough to die of sleep deprivation unless you actually have a condition preventing sleep.
I'd be skeptical of what you claimed. There are similar diseases to FFI which involve dementia, hallucination and death -- but don't involve insomnia. The insomnia might just be another symptom.
Besides which, if you deprived yourself of sleep to that point, I expect you'd just go to sleep.
Diseases with similar causes such as CJD also involve hallucinations and dementia and don't involve lack of sleep, so I'm not 100% convinced that it's the lack of sleep that is causing the death in these cases, although it's an interesting data point.
I agree. Fatal familial insomniac's death is brough about by neurodegeneration caused by prions. Another non-fatal illness which inhebits sleep for extensive periods is Morvan's syndrome [0] for which there has been EEG recordings showing no sleep for 4 months [1] and showing no imparement of memory or intellectual performance!
http://en.wikipedia.org/wiki/Fatal_familial_insomnia#Treatme...