When I am awake I see up and down and all the three dimensions as a present and irrefutable reality. In a dream I also experience those very same three dimensions but when I reference that experience in waking I correlate it with my physical body(brain) and not with a real independent feature of reality. While the idea that dreams represent the possibility that the world is an illusion is a persistent philosophical question I am more concerned here with how an abstract feature that seems to convey a part of the essence of what we call physical reality, that is to say dimensionality, is undermined by our dream experience. It seems that dreams demonstrate that dimension is not necessarily as commonsensical a feature of physical reality as it appears. Isn't dimension a feature which is central to our modern scientific understanding of physical reality and then don't dreams then call into question much of scientific understanding?