When was the last time you were assigned a random stranger as a roommate? Probably not since freshman year—unless, of course, you end up in a hospital. Shared rooms are common in most hospitals, a convention that evidence-based design experts warn may cause poorer health outcomes.

Many new hospitals are switching over to single-occupancy rooms, the New York Times reported this week. Studies have found single rooms lower the likelihood of infection, and allow patients to feel less stress and get more sleep. The American Institute of Architects' Guidelines for Design and Construction of Hospital and Health Care Facilities in 2006 called for the construction of single, rather than double rooms in all hospitals.

Shared rooms increase the spread of disease through contact with surfaces such as bed rails, tables and bathroom fixtures, Roger Ulrich, a member of the board of directors for the Center for Health Design told the Los Angeles Times. This is especially troubling as hospitals work to combat dangerous hospital acquired infections such as MRSA.

Sharing a room can add to patient stress. "I have to walk past his family on the way to the bathroom," Jay Paszamant, a patient at University Medical Center at Princeton in Plainsboro, New Jersey, told the Times. "And I feel uncomfortable overhearing my neighbor's issues. I don't want to invade his privacy."

The best health centers, the Times reports, are light-filled, quiet and easy to navigate, and design has a significant impact on care delivery. The Center for Health Design's Pebble Project studies the relationship between health quality and design through a network of partners and pilot programs. One such program at Parrish Medical Center, in Titusville, Florida, was able to decrease employee turnover by nearly 10 percent and improve patient care through design strategies such as increased access to natural light, improved airflow, separation of public/patient transport areas, and "homelike" patient room designs.

The Pebble Project has tracked the success of other simple strategies across the US, such as installing noise dampening carpet and acoustical tiles at St. Alphonsus Regional Medical Center in Boise, Idaho, to reduce noise and help patients get more sleep at night. The Bronson Methodist Hospital in Kalamazoo, Michigan, found that private rooms, well-placed sinks, and better airflow helped to bring down hospital-acquired infections by 11 percent.

Using evidence-based design as a guide to building hospitals means that the facilites aren't just newer and more attractive—they're also safer, smarter, and more helpful to clinicians and patients. This is an important cornerstone in successful health reform: find out what works based on evidence, and build those practices into a better system.