Whether regarded as an evolutionary accident that piggybacked on language or as the gateway to our emotions, music activates parts of the brain that can trigger happiness, releasing endorphins similar to the ways that sex and food do. Music can also relax the body, sometimes into sleep as it stimulates the brain's release of melatonin. A study of older adults who listened to their choice of music during outpatient eye surgery showed that they had significantly lower heart rates and blood pressure, and their hearts did not work as hard as those who underwent surgery without music. A second study, of patients undergoing colonoscopy, showed that listening to their selection of music reduced their anxiety levels and lessened the dosage required for sedation.