Cortisol, a hormone secreted by the adrenal glands in times of stress, may help people cope when it is given before an unpleasant situation.

Most studies of cortisol have looked at the hormone's negative effects when chronic stress keeps its levels high. Psychologists Oliver T. Wolf and Serkan Het of Bielefeld University in Germany were interested in the short-term effects of cortisol on mood. They gave 22 young women 30 milligrams of cortisol—a fairly high dose. A control group of 22 women received a placebo.

All the subjects were then put in a stressful situation. They were asked to give a speech in a fake job interview and afterward to count backward by 17s from a large number while being monitored by stern-faced examiners and videotaped the whole time. The women were given mood questionnaires before and after their interview.

“The women who got cortisol—compared with those getting placebos—reported less negative effect after the stress test,” Wolf says. Exactly how cortisol provided this protection is not clear.

“Cortisol is active in several brain regions that modulate emotions,” Wolf explains. “One possibility is that cortisol interferes with retrieving emotional memories, so the subjects weren’t able to recall their unpleasant experiences as well.” If this is true, he adds, it could point the way toward using cortisol to treat people who have survived terrible events and suffer from posttraumatic stress disorder (PTSD).