Its hard to say but if you don't receive stimuli impulses from your brain of the external world (if that even exists) then what would you dream about? Without that sense, what would these dreams consist of if you haven't experienced anything? Moreso if a blind person doesn't know what they look like in reality will dreams, if they even happen, make the person appear as just an observer? Also, deaf people must not be able to hear anything in their dreams. This would suck, dreaming is one of the greatest things.