Being in a relationship can help us deal with the many hurdles life throws at us, such as sharing the load financially and emotionally.

Now, new research has found that a supportive partner can also protect our physiological health, especially as we age.

As part of a study led by University of California psychologists, the research team analysed the data from 321 adults, aged from 56 to 87 years of age across three intensive studies in Canada and Germany between 2012 and 2018.

They then compared people’s self-reported emotional states and their relationship satisfaction with levels of cortisol measured by saliva samples. In all three studies, people’s emotional states and cortisol were measured multiple times each day for a full week.

The study found that a person’s body produced less cortisol when their partner reported higher positive emotions than usual and this effect was even stronger than when people reported their own positive emotions.

The team also found those with higher relationship satisfaction experienced a stronger effect, where a partner’s positive emotions were better at lowering cortisol than one’s own emotions.

While cortisol is an important part of our bodies’ stress response and everyday function, extremely high levels of cortisol can lead to overall poorer health. Studies have found that negative emotions are linked to higher levels of cortisol and older adults have trouble slowing down their cortisol production as they age.

University of California Associate Professor Tomiko Yoneda said the existing research has shown how important positive emotional experiences are for health outcomes.

“Having positive emotions with your relationship partner can act as like a social resource,” she said.

Yoneda said results were consistent with prior research that suggests positive emotions increase our ability to act more fluidly in the moment, which can then create a positive feedback loop that enhances this ability over time.

“Relationships provide an ideal source of support, especially when those are high-quality relationships,” she said.

“These dynamics may be particularly important in older adulthood.”