Oxytocin's hidden power: pupil test reveals nervous system secrets

This study looks at how oxytocin, a natural hormone, affects the part of your nervous system that controls rest and digestion. Researchers will give a single injection of oxytocin or a placebo to 38 people (some with knee arthritis, some healthy) and measure tiny changes in pupil size over time. The goal is to understand how oxytocin works in the body, not to treat any condition.