i dont know about scientific knowledge on dreams, but do have some philosophical knowledge on not "psychology" of dream but philosophy of dream.. We never dream of dreams that is far out of our own intellect reach, because dreams happen due to past experience, memories and with help of our capable knowledge and wisdom. A child will never dream of solving a very difficult economic problem, because firstly he doesnt have experinece with economics, secondly, he hasnt had any memories that have been in field of economics and lastly his intellect is not capable of solving such mathematical problem, because again, simply he has not yet reached or touched such wisdom, so therfore he will never dream of a soliving a very difficult economic problem. When we fall asleep, our "mind" is not functioning with the body but rather on its own, hence we do not come accross with any laws of physics, or any general laws of nature.so it is possible for us to witness ourselves being a "superman" and shooting dangerous rays from of our eyes. When we are sleeping our "mind" is not functioning with any of our surrounding, but on its own, so anything is possible on dreams. and if you happen to witness a death dream, then it is just a memory of something bad or a bad experience you had that stayed with you, and was processed while you were sleeping without the external organ being involved..bad experince usually leads to death dream because death is something we have fear of in our minds, just like doing, committing or being involved in bad experience. ok since we are talking about dreams, i cant stop myself but wrte a few lines on Descartes Meditations of first philosophy.. On his meditations of first philosophy, Descartes brings everything into doubt and he establishes a point saying you can never know if you are dreaming or you are awake. You might be sitting on ur luxurious comp. chair and typing in your sajha, but you could be doing this with your eye closed. So acutally you are not typing rather you are just dreaming about typing, but how do you know, you are just dreaming and not really typying? you dont, and cannot differenate between reality and dream. By giving such arugments, Descates states another short, but very powerful arguments, he says, "cogito ergo sum,", which simply means, I think, therefore i am, so conclusion is you never know if you are dreaming or not, but if you are thinking than you surely exist... haha like DWI, i might also have lots of gramatical mistakes, ooh well, i am NOT re-reading and correcting those..if you understand it, its fine, if u dont, haha, bad luck..