It’s not uncommon to feel disorganized and forgetful when you’re under a lot of stress. But over the long term, stress may actually change your brain in ways that affect your memory. Studies in both animals and people show pretty clearly that stress can affect how the brain functions, says Dr. Kerry Ressler, chief scientific officer at McLean Hospital and professor of psychiatry at Harvard Medical School. Scientists have seen changes in how the brain processes information when people experience either real-life stress or stress manufactured in a research setting. (For the latter, researchers might challenge subjects to perform a difficult task, such as counting backward from the number 1,073 by 13s while being graded.) Either type of stress seems to interfere with cognition, attention, and memory, he says.