Scientists from the University of California, Davis (USA) have found that shared positive emotions with a partner can reduce stress hormone levels and have a lasting beneficial effect on the body. The study was published in the Journal of Personality and Social Psychology (JPSP). The study involved 321 couples of older adults from Canada and Germany. Over the course of a week, participants reported their mood several times a day—how happy, calm, or interested they felt—while simultaneously providing saliva samples for cortisol level analysis. Nearly 24,000 measurements were collected in total. The results showed that when partners experienced positive emotions simultaneously, their cortisol levels decreased more significantly than in cases where joy was experienced individually. Moreover, this effect persisted throughout the day, helping the body remain calm and reducing physiological stress. The authors emphasize that shared positive emotions acted independently of how satisfied people were with their relationships. Even couples with less harmonious dynamics felt the calming effect. According to lead author Tomiko Yaneda, sharing joy may be one of the simplest and most natural forms of health care.