As we know, if you don't dream you will cease up and die. So, by depriving someone of dreams and sleep you basically put them in so much shit it is impossible to measure any particulars. I know one of the theories of what dreaming is actually for is to 'sort out your memory', however that works. So, I was wondering if there is any data whatsoever to suggest that it is absolutely crucial to memory.

I figured that the most likely clients for study would be people with 'dream disorders', because you couldn't deprive just anyone of dreams. To do that would mean you deprive them of sleep, which would lessen pretty much all brain functions, so you wouldn't be able to tell anything. But, I don't really know if 'dream disorders' actually exist. I have heard of people dreaming in black and white, and of course lucid dream naturals (I know one personally). But is what I'm looking for findable?

Just one last note; I have heard vaguely of experiments in which people were deliberately woken up during REM but allowed to sleep otherwise normally. I don't think it was testing memory though.