Stress produces cortisol which reek havoc on your brain. Studies revealed that stress causes poor memory and those afflicted with chronic stress had a reduced hippocampus, the part of the brain that is responsible for learning. Learn to relax through meditation, yoga, or prayer. Research has shown that those who practice meditation had more gray matter in their brain than those who did not practice a form of meditation. Gray matter is important for attention, emotion regulation, and it enables mindful decision making.