Many people have experienced reductions in stress, pain, and anxiety—and sometimes even euphoria—after exercise. What’s behind this so-called “runner’s high”? New research on the neuroscience of exercise may surprise you. The “runner’s high” has long been attributed to endorphins. These are chemicals produced naturally in the bodies of humans and other animals after exercise and in response to pain or stress. However, new research from my lab summarizes nearly two decades of work on this topic. We found that exercise reliably increases levels of the body’s endocannabinoids—which are molecules that work to maintain homeostasis, the essential physiological balance in the brain and body. This natural chemical boost may better explain some of the beneficial effects of exercise on brain and body. I am a neuroscientist at the Wayne State University School of Medicine. My lab studies brain development and mental health, as well as the role of the endocannabinoid system in stress regulation and anxiety disorders in …