The long-established trend toward loft-like living means that having a bed in the middle of your living space is now considered a lifestyle choice, like an open kitchen or a wall-free bathroom. Many one or two-person households now prefer to keep their interior spaces open, with an integrated sleeping area instead.

For years, one of the best ways to achieve the open-plan bedroom has been to install a Murphy bed — a hinged bed that folds vertically into a wall closet when not in use. Legend has it that in the early 20th century, William Lawrence Murphy applied for a patent on the device, which he devised to turn his bedroom into a parlor to make it socially acceptable for him to entertain ladies. The Murphy bed surged in popularity in the 1920s and 1930s when buildings like those on the far east side of Manhattan were developed; special Murphy bed closets made these diminutive studio apartments more livable during waking hours. But these clever beds, which were often uncomfortable and shabbily made, lost their allure after World War II as people flocked to houses in the suburbs.

Nevertheless, the fold-up wall bed has quietly been making a resurgence in recent years, as the world's population becomes increasingly urban, family sizes are shrinking, more people are choosing to live alone, and the price of real estate in crowded cities becomes more and more unaffordable. Companies worldwide are designing beds that disappear into walls, can be stowed via remote control, or even stored on the ceiling.

Even in super-sized North America, the so-called micro-condos popping up in cities like New York, Washington, D.C., San Francisco, Toronto and Vancouver have become an archetype for the ruthless space planning required to make modest spaces not only livable but enjoyable.

And a growing number of these projects are installing upscale wall beds that turn back into sofas (or dining tables, or desks, or bookshelves, or wall-storage units) by day, giving the small-space dweller the equivalent of a secret room. The design leader of cleverly engineered, high-end, top quality transformable furniture is Clei, the family-owned, Italy-based company that is available in the United States via Resource Furniture.

Graham Hill, the Treehugger founder who now runs Life Edited, an interior design specialty consultancy that focuses on intelligently designed small spaces, said that he stumbled across the furniture when looking to equip his own company prototype apartment in New York. At 420 square feet, it can sleep four, seat 12 for dinner, and serves as a home office.

"The Murphy bed is a key part of the design," Hill said. "But there are so many that are cheesy and low-quality. … We're trying to create something really compelling and sophisticated that doesn't feel like you're sacrificing anything. These don't feel gimmicky or cheap but like a great bed, and a great piece of machinery."

The dedicated bedroom is actually a fairly recent phenomenon, according to British curator and historian Lucy Worsley, who wrote "If Walls Could Talk: An Intimate History of the Home." Medieval servants often bunked together in a shared hall, she points out. It wasn't until Victorian times, it seems, that dedicated bedrooms became the norm.