Stress can help or hurt learning depending on when the stressor hits. As psychologists well know, exposure to brief stress just before an event can enhance long-term memory of that occurrence. Had the stressful experience descended 30 minutes prior, learning would instead have been impaired. A new study published in the February Neurobiology of Learning and Memory now finds that the effect is sex-dependent.

Male and female participants were randomly assigned to one of two groups: For three minutes, one group submerged a hand in ice-cold water, while the control subjects placed their hand in warm water. Thirty minutes later they attempted to memorize a list of words on which they were tested 24 hours later.

Men who exhibited a robust physiological response to the stress of the ice bath, as measured by levels of the hormone cortisol in their blood, could not recall as many words as men who were less fazed by the cold, men in the control group, or women in both groups. Women who had a minimal cortisol response to the ice water performed better than the control groups, although the difference was small. “Males appear to be more sensitive to stress- and cortisol-related impairments of learning and memory,” says Phillip R. Zoladz, co-author of the study and professor of psychology at Ohio Northern University. Some studies suggest that in women, stress effects may be mediated by stages of the menstrual cycle, which can alter sensitivity to stress hormones, but the new study did not investigate that variable.

Only a physiological test can truly determine whether your memory is vulnerable to prelearning stress, but signs such as a racing heart and sweaty palms may be clues that you might be prone to this effect. If so, tried-and-true memory-boosting techniques can help. “If stress is causing forgetfulness, it can be helpful to use reminders—like sticky notes placed where they will catch your attention—to trigger a memory,” Zoladz says.