First, it was red wine. Then chocolate. Now, stress—like a lot of things—can be good for you in moderation. Although studies have shown that too much stress boosts your risk of obesity, heart disease and depression, occasional stress might be a boon to the brain, according to a recent study on rats at the University of California, Berkeley. Rats that stressed out for three hours released fibroblast growth factor 2 (FGF2), which in turn triggered the development of new nerve cells in the hippocampus, part of the brain central to memory, says study author Daniela Kaufer, associate professor of integrative biology at UC Berkeley. Too much stress has the opposite effect, however, suppressing the growth of neural stem cells and undermining memory.