And doctors may someday induce a drastically low body metabolism and temperature to keep trauma patients alive. Reducing oxygen needs could decrease tissue damage in cases where the body can't get as much oxygen as usual, for example during a heart attack. Mark Roth, a biologist at the Fred Hutchinson Cancer Research Center in Seattle, is working on a suspended-animation treatment that could do just that. He has shown that having mice inhale air infused with hydrogen sulfide decreases their breathing rate by 92 percent and also drops their body temperature. After he revives them, they recover completely and behave normally.