Futons
Everyone and their cousin had a futon at some point in the last 30 years. Hailed as the ultimate in versatile furnishings, bringing the concept of saving space over from Japan, you could have a sofa and then switch to a sleeping surface with minimal fuss. Particularly common in student flats there was a time when you couldn’t go anywhere without seeing (or sleeping on) one.
There were problems, though. They acted as both seating and bedding but did neither well enough to be comfy. You ended up with a lumpy mattress and a sofa that you could never get comfortable on. Modern sofa beds have a more substantial construction, better mattresses, and look altogether more stylish. Dump the futon and your back will thank you.