Feeling happy is good for everyone’s health, but sharing everyday happiness with a life partner brings even greater health benefits, according to new research from the University of California, Davis.

A new study suggests that when older couples experience positive emotions together in everyday life, they have lower levels of the stress hormone cortisol that can cause health problems over time when elevated. The study was published in August in the American Psychological Association’s Journal of Personality and Social Psychology. 

“This study’s findings underscore the importance of fostering positive shared emotions in close relationships, which may promote better physical health for older adults,” said Tomiko Yoneda, lead author on the study and an assistant professor of psychology in the College of Letters and Science.

The study is the first to demonstrate these results with couples in everyday life outside of a lab setting. 

Happiness with partners reduces stress hormone

There are strong links between feeling happy and the level of cortisol in our bodies. Cortisol is a hormone the body releases in response to stress. It plays an important role in our daily lives, from helping us wake up in the morning to dealing with danger. However, too much of it or at the wrong time of day, can cause health problems over time, including inflammation and a shorter life. 

The study analyzed data from three independent studies from Canada and Germany that took place between 2012 and 2018. The study included 321 couples (642 participants total) who lived together. They ranged from 56 to 89 years old. 

This study’s findings underscore the importance of fostering positive shared emotions in close relationships, which may promote better physical health for older adults. — Yoneda

Participants self-reported how they felt emotionally and provided saliva samples up to seven times each day for seven consecutive days. This high-resolution data pinpoints how participants felt throughout the day when apart and together, as well as their levels of cortisol.

Experiencing positive emotions together was associated with lower cortisol levels later in the day. On the other hand, cortisol levels on their own had no effect on the likelihood of reporting positive emotions later.

These effects were the same for both men and women — and for every age. Overall time as a couple or satisfaction in the relationship made no difference, which Yoneda said suggests that the health-related benefits of sharing happy moments aren’t only for the happiest couples. 

Both relationship partners reported feeling more positive emotions more than they normally do 38% of the time when together. 

How happiness protects health as we age

The study is the first to demonstrate these ideas with couples in everyday life outside of a lab setting.  

One limitation is that the research only included older couples who lived together. The results might not extend to happiness shared with friends, family or through other relationships.

At the same time, these findings suggest older adults can take control of their happiness together for a healthier future. Prior research has found that happiness can increase resilience to hardship and stress, build a stronger immune system and even lead to a longer life.

“These findings highlight that really prioritizing opportunities to share positive emotions with your partner can have meaningful momentary benefits for your health,” said Yoneda.

Co-authors include Nathan Lewis from the University of British Columbia; and additional co-authors from the University of British Columbia, Simon Fraser University, the Medical School Berlin, The Max Planck Institute, Humboldt Universität Berlin, Stanford University and Northwestern University.

The research was funded by the Canadian Institutes of Health and the German Research Foundation.