Everyday co-presence with a romantic partner is associated with lower C-reactive protein

• More time spent present with romantic partner in 24 hours associated with lower CRP. • Effect of time spent on CRP held when controlling for romantic relationship quality. • Effect of time spent on CRP held when controlling for hostility with partner. • Effect of time spent on CRP held when controlling for individual loneliness. • Everyday time spent together may be key link between relationships and inflammation. Social relationships are an important driver of health, and inflammation has been proposed as a key neurobiological mechanism to explain this effect. Behavioral researchers have focused on social relationship quality to further explain the association, yet recent research indicates that relationship quality may not be as robust a predictor as previously thought. Here, building on animal models of social bonds and recent theory on close relationships, we instead investigated merely being in the physical presence of one’s romantic partner. Specifically, we tested the hypothesis that spending more time co-present with a loved partner in everyday life would be associated with lower c-reactive protein (CRP). Three times over the course of one month, 100 people in romantic relationships reported how much time they spent in the same physical space as their partner in the prior 24 hours, in minutes, and provided a sample of blood for CRP assay ( n observations = 296). Results from multi-level models showed that when one reported spending more time in the physical presence of their partner they had lower CRP – an effect that was independent from social relationship quality explanations from the prior literature, including romantic relationship quality, hostility, and loneliness. These findings move past global assessments of social isolation to consider a novel everyday behavior that is of great interest in the non-human animal literature – spending time together -- as a potential mechanism linking high-quality relationships and physical health in adult humans. The findings also point to future research on additional behavioral mechanisms that are not dependent on stress pathways: people in high-quality relationships tend to spend enjoyable and affectionate time with one another, which may impact inflammation.