27 Ways To Rethink Your Bed: Bed in a Closet. Also check out the Roll-Away Bed under a Platform; Cool way to quickly tidy up a small space, and keep pet hair off the bed! Maybe put a little reading or office space on top on the bed?
This is another example of a layout that would be easy to install in a studio apartment - a loft bed with stairs would be a cheaper and nicer space saving solution than buying a Murphy bed. Maybe even in a small bedroom.