The existence of other dimensions is proven now in scientific terms but little credence is given at present to the impact and the opportunity afforded by these alternate realms. Explaining other dimensions away by describing them as 'curled up' offers a neat solution to the fact that we can't perceive them in everyday life. But many people have seen ghosts and other apparitions which can only be explained by the multi-dimensional framework, and many more (including harsh sceptics) have experienced out-of-body experiences which again rely on the mind's ability to access realms we cannot normally see. Out-of-body experience has now been proved under laboratory conditions and this equates to an important step in our understanding of consciousness - how much flexibility we have to cross the dimensional states is just being opened to serious investigation.
Dreamscape may be part and parcel of our ability, inherent as it's proving to be, to traverse various dimensions. Many forms of illusion, delusion or hallucination can also be explained in this way, giving credence rather than ridicule to people who suffer from invasion of such things in conditions such as schizophrenia. Science fiction is no stranger to the alternate-dimension theory and it has been used in many ways many times to underpin good storylines.
The mind is potentially far more powerful than most people concede. Not only can it travel remotely from the body, it can heal the body too. Equally, the mind can damage the body, manifesting unwanted physical symptoms. How we use our mind is of great significance in how we lead our lives, therefore cultivating our thoughts wisely and with good intent has to be the best route to a beneficial existence. Thinking well leads to wellness, thinking ill leads to illness. Not just in our singular selves, but across the span of our reality - our relationships, environments and networks are all affected by how we think. With more than three dimensions to choose from, our options are legion - in a later post I'll investigate more deeply the role of the Multiverse in our personal routes through cause and effect. (For now, the interpretation linked above is the most straightforward explanation I could find.) In the meantime, enjoy your dreams, and the many opportunities within your constantly shifting spacetime.