People who do serious running and other exercise often report higher spirits and lower anxiety. This “runner’s high” is usually attributed to an increased production of endorphins — the body’s own natural opioids.

Many scientists have doubted whether runner’s high exists, however; they couldn’t reproduce it reliably in the lab, or confirm the endorphin hypothesis. “This endorphin-in-runners is a total fantasy in the pop culture,” commented the president of the Society for Neuroscience in 2002.

Now, researchers in Bonn and Munich have settled the controversy: an endorphin-induced runner’s high unquestionably does exist.

Using advances in PET scanning (positron emission tomography), they took high-resolution pictures of runners’ brains before and after two hours of running. The “after” images showed a significant increase in endorphins, and exactly where they were located.

“It’s interesting to see that the affected areas were [ones] known to play a key role in emotional processing,” says Prof. Henning Boecker. “Moreover, we observed a significant increase in euphoria and happiness ratings.”

A dedicated program of exercise, it seems, could be a significant adjunct to psychotherapy aimed at lasting change, and in this case, you don’t need a prescription.