We may look back on the summer of 2007 as the year the bed moved outdoors.

Weatherproof mattresses in hardy teak, metal or woven resin frames are landing this season at major retailers across the land, ready for snoozing al fresco. Called sun beds, daybeds or lounges, they are a new category of outdoor furniture in national chains and home centers, sporting amenities such as mildew-resistant cushion covers and mosquito-netting canopies. Sleepover under the stars, anyone?

Americans have already bought in big to the outdoor living room and kitchen. “Now it seems like the whole house is emptying into the back yard,” says Stephanie Yonkers, a spokeswoman for Crate and Barrel.

Besides the bedroom, all-weather furnishings for the formal dining room, home theater, wet bar and even the shower are now on the market. Can home office furniture be far behind?

There has been a sharp rise in the popularity of outdoor living space, according to a survey done last year by the American Institute of Architects, with two-thirds of architects reporting an increase in demand for outdoor kitchens, patios and decks. “We are coming off of probably the biggest home improvement surge in our history,” says Kermit Baker, the institute’s chief economist. “Land costs have been rising so rapidly … consumers want to invest more in their property.”

Trend forecasters have sexier theories. “There is a total celebration of nature going on,” says Marian Salzman, executive vice president at J. Walter Thompson and co-author of “Next Now,” a book on forces shaping our culture. “We are so worried the environment is a precarious place, we want to embrace nature whenever we can. There is something very special, even mystical about anything that we do outdoors.”

The outdoor living room started setting up on our patios, decks and courtyards a decade ago. For Smith & Hawken, the furnishing of the back yard began with the humble garden bench, says Jennifer Sypeck, Smith & Hawken’s director of trend and product development. As the years progressed, customers wanted much, much more. “They wanted not just to sit, but to lounge.”

Soon, suburbanites were drinking martinis around glowing fire pits and impressing neighbors with their macho monster stainless grills. Consumers accessorized with every conceivable indoor gadget and embellishment that was made weather-impervious: umbrellas, chandeliers, rugs, lamps, wall art. Now, the outdoor bedroom.

“People are watching shows like ‘Extreme Makeover: Home Edition,’ where every time they redo a back yard, they put in a huge grill and a swimming pool and lots of seating,” Yonkers says. “Everyone wants to be as comfortable outside as they are inside.”