Narrator: This is Science Today. If you've ever undergone surgery, the cold operating room and the anesthetics dropped your body temperature by four degrees. Anesthesiologist Daniel Sessler of the University of California, San Francisco says that's a lot.

Sessler: Body temperature is extraordinarily tightly regulated. At any given time of the day, body temperature is within a half degree Fahrenheit of where your body wants it. So when patients become four degrees hypothermic during surgery, that's way way outside the normal tolerance for the thermoregulatory system.

Narrator: Sessler suspected that keeping patients cold caused problems for them as they recovered. He compared 200 cold patients with 200 patients who were kept warm. The results:

Sessler: You're three times less likely to get an infection if you're kept warm.

Narrator: Fortunately, Sessler found that surgical patients can be kept warm with a 30 dollar heating blanket. Surgeons and anesthesiologists around the world have hailed Sessler's discovery. For Science Today, I'm Steve Tokar.