You're under my skin: Long-term relationship and health correlates of cortisol synchrony in older couples.
Level 3 - non-randomized controlled study
Prospective longitudinal observational cohort study tracking dyadic physiological markers over 3 years.
PubMed 33151708 · doi:10.1037/fam0000809
What was done
Researchers investigated the relationship between daily cortisol synchrony, relationship satisfaction, and non-high-density lipoprotein (non-HDL) cholesterol over a 3-year period in 85 older couples (age range 60–87 years, N = 170 individuals). Participants provided saliva samples 5 times per day for 7 days to estimate everyday cortisol synchrony. Relationship satisfaction and blood lipid samples were collected up to three times at 1-year intervals and analyzed using dyadic growth curve models.
What was found
In wives, higher cortisol synchrony was associated with stronger increases in relationship satisfaction over time (b = 1.61, p = .011) but also stronger increases in non-HDL cholesterol levels over 3 years (b = 2.02, p = .042). In husbands, cortisol synchrony showed no significant association with relationship satisfaction levels or trajectory, but was associated with higher non-HDL cholesterol levels at baseline (b = 6.54, p = .015).
Why it matters
These findings suggest that while physiological synchrony may support social bonding and marital satisfaction in older adults, closely sharing a partner's physiological stress responses may carry long-term metabolic or cardiovascular costs.
Limits
The sample size was modest (85 couples) and restricted to older adults, limiting generalizability to younger or more diverse populations. The observational design cannot establish causality between cortisol synchrony and cardiovascular risk markers, and unmeasured lifestyle factors (such as diet, physical activity, and medication changes) were not reported in the abstract.